SGP/AOS/C1 - CN counter removed

The AOS condensation particle counter performance degraded to unacceptable
levels and was removed for repair.  

For the first time period: upon inspection of the internal condition of the instrument, it 
was found that oil was present in the intake line.  It is unknown how this oil could 
have arrived in this position.  The instrument was thoroughly cleaned and back-flushed, and 
returned to service during the maintenance visit.

For the second time period: The degradation of began July 8th.  Data collected during this 
time period are either incorrect or missing and should not be used.

SGP/AOS/C1 - Nephelometer failure

An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer 
humidograph system during a Friday Preventative Maintenance.  This resulted in liquid 
water getting into the humidified nephelometer.  Flow was restored to the system on Monday, 
but the nephelometers were producing strange data.  A number of tests were performed 
over the next few days to remotely troubleshoot the situation, to no avail.  Eventually, the 
decision was made to pull both nephelometers and return them to Boulder for repair.  
This DQR refers only to the reference nephelometer, which was out of service for 2 periods 
due to 2 separate problems.  This DQR is for the first period, from 000602 (1842 GMT) to 
000616 (2234 GMT).  Light absorption are invalid whenever the reference nephelometer is 
not operational, because those data are required for correction of the absorption data.

SGP/AOS/C1 - Nephelometer failure

An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer 
humidograph system during a Friday Preventative Maintenance.  This resulted in liquid 
water getting into the humidified nephelometer.  Flow was restored to the system on Monday, 
but the nephelometers were producing strange data.  A number of tests were performed 
over the next few days to remotely troubleshoot the situation, to no avail.  Eventually, the 
decision was made to pull both nephelometers and return them to Boulder for repair.  
This DQR refers only to the reference nephelometer, which was out of service for 2 periods 
due to 2 separate problems.  This DQR is for the second period, from 000620 (1340 GMT) to 
000703 (1833 GMT).  Light absorption measurements are invalid whenever the reference 
nephelometer is not operational, because those data are required for correction of the 
absorption data.

SGP/AOS/C1 - Nephelometer failure

An inexperienced AOS technician inadvertently closed off the flow to the dual-nephelometer 
humidograph system during a Friday Preventative Maintenance.  This resulted in liquid 
water getting into the humidified nephelometer.  Flow was restored to the system on Monday, 
but the nephelometers were producing strange data.  A number of tests were performed 
over the next few days to remotely troubleshoot the situation, to no avail.  Eventually, the 
decision was made to pull both nephelometers and return them to Boulder for repair.  
This DQR refers only to the humidified nephelometer, which was out of service for the entire 
period from 000602 through 000703.

SGP/AOS/C1 - AOS Computer Failure

The AOS computer started to experience periodic failures caused by an aging and failing 
system disk.  Replacement of the AOS computer's system disk occurred between 2-4 June 2002.

SGP/AOS/C1 - Ozone instrument out of service

The ice storm of 30-31 January, 2002 shut down the AOS for ~2 weeks.  A controlled 
power-up of the system found a problem with the ozone monitor.  Smoke was observed to come from 
the ozone instrument, at which time it was shut down.

The ozone monitor was removed from the AOS for remote troubleshooting. The cause of the 
smoke was identified as being from underneath a printed circuit board.  At that point, Site 
Ops staff were requested to send the unit to Boulder for additional troubleshooting.  
NOAA staff received the unit on 20 February 2002.

After a brief inspection, the cause of the smoking was discovered.  A one-half inch hole 
was burned completely through the motherboard.  The determination was made that this could 
not be repaired at the NOAA facility, and a purchase order was initiated to return the 
unit to Dasibi, Inc. (the manufacturer), for repair/replacement of the motherboard.

On 4 March, 2002, NOAA personnel received the OK from ARM to return the instrument to 
Dasibi, Inc. for service.  Dasibi, Inc., received the unit on or around 8 March, 2002.  The 
manufacturer was to test the unit, repair or replace the damaged motherboard, and 
calibrate the unit according to the NIST standard protocol.

On 8 May, 2002, NOAA personnel emailed SGP Site Ops personnel and asked them to check on 
the status of the repair, which was taking longer then expected.   Upon trying to contact 
the manufacturer, it was discovered that they went out of business.  The return of 
instruments from the manufacturer to customers was being handled by a contract company.  The 
ozone monitor arrived back in Boulder, in an unrepaired state, on or about 1 July 2002.

Since there were few other options, NOAA personnel undertook the difficult task of 
repairing the motherboard.  This required the re-routing of several electrical conduits from the 
burned area in the multilayer board to other acceptable places on the board.  This took 
a considerable amount of electronics technician time and effort.  After the motherboard 
was repaired, extensive testing was required to verify that the repair was done 
successfully and that other problems were not caused in the unit by the board burning..

The repair was deemed successful on 24 September, 2002.  The unit was shipped back to the 
SGP site immediately thereafter.  It was installed during a NOAA AOS maintenance visit on 
1 October, 2002.

SGP/AOS/C1  - Data missing

The UPS supplying power to the AOS computer failed on Friday, 12/27/2002.  The UPS was 
repaired on Monday 12/30/2002, but the AOS computer was locked up and would not reboot.  
Telephone communication was established with Richard Eagan, ANL, who was able to do a remote 
reboot of the computer using his account.

SGP/AOS/C1 - Ozone Instrument removed for repair

The ozone instrument was removed for calibration on 2003 11/21.  It was shipped to Boulder 
and was cleaned and calibrated.  It was sent back to SGP on 2003 12/02, but was damaged 
in transit by FedEx.  The instrument was reinstalled on 2003 12/03 but was found to be 
defective.  Large spikes were observed in the data.  Afetr a few days the instrument was 
removed and shipped to a vendor for repair.  The ozone monitor was returned to service 
after repair at 2004 01/27 (2208 GMT).

SGP/AOS/C1 - PCASP instrument problem

PCASP (optical particle counter) gave unusually low aerosol signal counts despite numerous 
attempts to fix the instrument by the mentor and manufacturer.

SGP/AOS/C1 - Ozone instrument removed for repair

The ozone monitor was removed and sent back to the manufacturer for repair.

SGP/AOS/C1 - Condensation Particle Counter failure

The CPC signal declined to a low value. The instrument was shipped back to the mentor, 
cleaned and repaired. The instrument inlet was clogged.

SGP/AOS/C1 - Wet nephelometer problems

The humidifier tube was coated with mold and had to be replaced. This affects the wet 
nepheleometer measurements and the calculations of the aerosol hygroscopic growth.

The humidifer was cleaned and replaced. A filter was added to the water circulation to 
minimize mold.

SGP/AOS/C1 - Failed RH sensor

The RH sensor inside the humidified nephelometer began to slowly decline in value in the 
upper RH range beginning in early 2004 and becoming more noticable poor on 20041117. The 
sensor currently reaches a high RH value of about 60% when the actual RH is closer to 80%.

The sensor was replaced in the Spring of 2005, but the problem remained.  Effective 
1/1/2004, this sensor is not used to calculate scientific data and is therefore essentially 
abandoned in the field.  An end-date of 20050501 is being used as a placeholder.

SGP/AOS/C1 - wet nephelometer out of service

The humidified nephelometer was removed and shipped back to CMDL to test and work on the 
relative humidity sensor inside the instrument.

SGP/AOS/C1 - Nephelometer calibration drift

Bad span check on the humidified nepehelometer.  Instrument was recalibrated and returned 
to service on 10/28/2005 at 1940 UTC.

NIM/AOS/M1 - Mass flow controller failure

The mass flow controller stopped working. A replacement one was installed at the site.

NIM/AOS/M1 - Nephelometer failure

There was was an electronic problem with one of the nephelometer circuit boards and the 
measurements of aerosol scattering coefficients were not recorded.

SGP/AOS/C1 - Missing Condensation Nuclei Counter data

AOS Condensation Nuclei Counter stopped detecting particle counts and was returned to 
mentor for cleaning.  The instrument has small orifices and has a tendency to clog.

NIM/AOS/M1 - Bypass valve failure

The flow bypass valve failed which routed flow through the bypass line rather than through 
the instruments. The bypass line was capped the next day. The valve was replaced on 
4/19. Data is considered unusable during the time between the valve failure on 3/22 and the 
capping of the flow line on 3/23.

NIM/AOS/M1 - Impactor switch stuck in 10 micron mode

A wire came loose in the ball valve that switches between the two impactor size cuts. The 
impactor was stuck on the sub 10 micron size cut during this period of time. There was no 
data from the sub 1 micron size cut during this time.

NIM/AOS/M1 - Flow controller failure

Following a power outage at the site both a PID controller for the main sample flow as 
well as a circuit board on the reference nephelometer were inoperable. The PID controller 
was replaced on 5/18 and the neph circuit board was replaced on 6/22. On a site visit in 
August the mentor found the PID had not been programmed correctly and was reading erroneous 
flows. The actual flow was at 50% of the recorded flow. Because the sample flow is 
diluted by 50% this makes most if not all of the sample flow from 5/18 to 8/11 from the diluter.

NIM/AOS/M1 - Missing data

Data are missing and unrecoverable.

SGP/AOS/C1 - Humidifier controller failure

Watlow PID controller which controls the humidifier stopped working. This mostly affects 
calculated fits of fRH

SGP/AOS/C1 - CPC failure

The Condensation Particle Counter stopped recording counts. Upon inspection the tech found 
that water had condensed in the reservoir. The CPC was shipped back to the mentor for 
repair and a replacement CPC from NOAA was sent to the site.

The replacement Condensation Particle Counter stopped measuring particle counts and was 
removed and returned to NOAA. The thermoelectric cooler in the device had stopped working. 
The ARM CPC that had previously been sent back to NOAA for repair was fixed and returned 
to SGP.

FKB/AOS/M1 - failed neph motor

The chopper motor in the "dry" nephelometer (Neph1) stopped working on Julian day 343.15 
or 12/9/07 0330 UTC. This motor controls a chopper wheel which alternates the signal 
between a "dark" phase, "calibration" phase and signal. Logging on the instrument was turned 
off on 12/18/2007 at 0100 UTC.The second nephelometer (Neph2) was used to replace Neph1. 
Data logging resumed on day 352 or 12/20/2007 using the replacement neph. From day 347 to 
352, Neph 2 was logging data without use of the humidifier. The neph2 data during this 
time can be used as the dry neph scattering coefficients.

FKB/AOS/M1 - Neph motor failure

Because of motor failure on Neph1 the logging of this instrument was turned off. The data 
logging on Neph2 was switched to log the dry scattering coefficients. The humidifier 
scanning was disabled.  

There are no Wet or humidified measurements of the aerosol scattering coefficients during 
this time period.

SGP/AOS/C1 - Pump failure and subsequent failure of humidified nephelometer

The pump for the aerosol sampling system failed over a weekend. The humidifier continued 
to operate and soaked the inside of both the reference and wet nephelometers. The 
nephelometers were returned for repair. A replacement neph was installed on 2008-August 5 @1858 
UTC. The nephs were repaired and returned to SGP in December 2008. The humidification 
system was rebuilt and installed on 2009 January 6 at 1912 UTC.

HFE/AOS/M1 - No sub 1 micron data

The aerosol size switching impactors were stuck in the sub 10 micron mode. So all aerosol 
is sub 10 um.

HFE/AOS/M1 - Humidifier failure

The humidifier either wasn't scanning or the wet nephelometer was flooded with water.

HFE/AOS/M1 - CPC data missing

The CPC wasn't installed until July 22nd when the mentor visited the site.

HFE/AOS/M1 - PSAP data missing

The PSAP was disconnected during this time period.

SGP/AOS/C1 - Annual maintenance

The instruments were not connected to the inlet while they were being cleaned and 
calibrated.

GRW/AOS/M1 - CPC TEC failure

The thermal electric cooler, which controls the temperature in the Condensation Particle 
Counter, failed. A new TEC was mailed to GRW. The TEC was replaced and the CPC was working 
again on Jan. 15th, 2010.

GRW/AOS/M1 - Annual maintenance

Instruments were down for annual maintenance.

FKB/AOS/M1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

GRW/AOS/M1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

HFE/AOS/M1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

NIM/AOS/M1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

NSA/AOS/X1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data.Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

PYE/AOS/M1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

SGP/AOS/C1 - Data processing problem

The AOS data was reprocessed for the AMF, SGP and NSA sites. There was an error in the 
processing of the corrections for the PSAP absorption signal such that a low pass filter was 
implemented for the scattering data used in these corrections.The difference between the 
corrected and previous data is < 0.05 Mm-1 (below the instrument detection limit) and 
should not have a significant effect on the previous data. Data will be reprocessed at a 
later time when more significant changes to the data processing are implemented.

SGP/AOS/C1 - Missing data

Data are missing and unrecoverable.

GRW/AOS/M1 - Discontinue fRH hygroscopic growth measurements

The chopper motor in the reference or dry nephelometer started to fail, which meant that 
it wasn't rotating at the correct rpm. The instrument gave erroneous data. 

The wet neph was swapped for the dry neph and the humidified nephelometer measurements 
were shut down. The neph motors were replaced at the end of the deployment so that both 
nephs will be operating for GVAX.

SGP/AOS/C1 - Nephelometer shutter error

The neph backscatter shutter started to fail which resulted in large background values in 
the dry nephelometer. The data is poor quality even though it may look ok.

Instead use the data in the wet nephelometer. Note that during some of this time period 
the RH value inside of this neph ramped up and down so use data at the low RH values.

HFE/AOS/M1 - CPC and CCN data questionable

The CPC slowly clogged and the signal declined until the instrument was cleaned at which 
point the signal would increase. The data is still a good relative measure of the daily 
changes in the CN concentration, but the absolute value may be too low.

The mentor was unable to monitor the flow rate and operation in the CCN during operation. 
The relative changes in CCN with %ss are likely fine, but the absolute values may be too 
low or too high. Dust was prevalent at the site and likely contributed to the CCN signal 
such that large dust particles appeared as droplets.

SGP/AOS/C1 - CPC leak

There was a slow internal leak in the CPC instrument and the data slowly decreased over 
time. The CN concentration is a lower limit and is likely 5 to 20% lower than the actual 
value with higher errors toward the end of the DQR period. The problem was fixed by 
replacing the CPC saturator block.

SGP/AOS/C1 - Missing data

Data are missing and unrecoverable.

GRW/AOS/M1 - CPC undercounting

The CPC was undercounting by about 10-20 percent relative to the CCN. After cleaning the 
CPC and replacing the butanol, the signal increased to above that of the CCN.

Increase CPC signal so that it equals the CCN signal at the maximum SS value. The 
corrected signal will represent relative and not an absolute particle concentration.

SGP/AOS/C1 - Missing data

Data are missing and unrecoverable.

SGP/AOS/C1 - Reprocessed: Bad PSAP flow cal

There was a leak in the flow calibration device that resulted in a lower than expected 
flow calibration. The data were reprocessed with a flow calibration that is the average of 
the flow cals taken before and after this time period.

SGP/AOS/C1 - Impactor valve failure

Solenoid valve for the impactor valve failed. All data for this time period are for sub 
10-micron aerosol.

SGP/AOS/C1 - PSAP data removed due to high RH

PSAP data was removed from b1 level data and VAPS because of high noise and negative 
values from high RH on filter.

SGP/AOS/C1 - Dry nephelometer failure

There was a communications problem with the nephelometer that resulted in intermittent 
data transmission and bad background values. The neph was removed for repair on Nov 15th. 

Use the wet neph data instead during this time as the humidifier was off. After this time 
the wet neph was put in the dry neph position until the neph could be repaired.

SGP/AOS/C1 - Leak in Condensation Particle Counter

Leak in Condensation Particle Counter (CPC) system.

MAO/AOS/M1 - System down for maintenance

Instruments were periodically offline or sampling room air during the cleaning, repair and 
calibrations.

SGP/AOS/C1 - Frequent power and communication loss problems

There were frequent power and communication losses over the time period. The problem was 
resolved after power was redistributed and all data acquisition components were replaced.

MAO/AOS/M1 - Sample line disconnected

While replacing the flow meter the tech left part of the sample line disconnected the 
system was sampling room air.

MAO/AOS/M1 - Dilution dryer momentarily off

SGP/AOS/C1 - New UPS installed

System down while new UPS is installed

MAO/AOS/M1 - Impactor stuck in sub 10 um state

Use data as is with designated size.

MAO/AOS/CLAP/NEPHELOMETER/PSAP/M1 - Leak in impactor

A leak existed in the impactor. The signal is about half what it should be for all 
instruments down stream of the impactor.

MAO/AOS/CCN/CLAP/CPC/NEPHELOMETER/PSAP/M1 - Power outage. No pump flow

Raw power which drives the pumps and heaters went out. There was no flow through the 
instruments.

MAO/AOS/CCN/CLAP/CPC/NEPHELOMETER/PSAP/M1 - Computer software issue

The computer software stopped collecting data and was rebooted.

MAO/AOS/CCN/CLAP/NEPHELOMETER/PSAP/M1 - Dilution compressor flow cycling on and off

The dilution flow was cycling on and off. This led to unstable concentrations. Dilution 
flow is about 30% of total flow so concentration uncertainty is on the order of 30%.

MAO/AOS/M1/S1 - Forest Fire

Smoke from forest burning can be seen on the TSI images rising and then subsequently 
moving over the site during this period.  Many of the AOS instruments observed a sharp spike 
in data values.

October 4-8 multiple fires in the area resulted in hazy conditions during this entire 
period.

Most notable in the following instruments and variables

ACSM - Total Organics
AETH - Black Carbon Concentrations at all wavelengths
CCN100 - Spike in number concentrations occurred a few hours after the smoke plume
CLAP3W - Absorption Coefficient
CPC - Similar to the CCN100, spike in particle concentration occurred a few hours later
CPCF - Particle Concentration
CPCU - Particle Concentration
NEPHELOMETERS - Scattering/Backscattering Coeff
PSAP3W - Absorption Coefficient
SMPS - Concentration and Size Distribution
UHSAS - Size Distribution

MAO/AOS/CCN/CLAP/CPC/NEPHELOMETER/PSAP/M1 - Reprocess: dilution flow communication 
intermittent

Communication with the dilution flow meter and communications is intermittent. Ports, flow 
meter and cable were swapped but to no avail. Visual flow meter was placed in flow line. 
This flow meter will be calibrated and the dilution flow corrected at that time.

SGP/AOS/CCN/CLAP/CPC/NEPHELOMETER/PSAP/C1 - System Maintenance

The system was offline for cleaning and calibration.

SGP/AOS/C1 - Pump and blower failure

The fuse on the power strip with the pump and blower blew. The blower motor seized and the 
blower had to be replaced.

SGP/AOS/C1 - Power outage

Power outage, no data collected.

SGP Site Power Outage Due to Winter Storm

On Saturday and Sunday, December 26 and 27th a powerful winter storm (Goliath) brought 
sleet and freezing rain to much of Oklahoma with wind gusts of 45 MPH at times. The result 
was very very slick roads and mass power outages.
 
The SGP central facility lost power at 8:55 PM CDT on Sunday, December 27th.  
The power was restored on 7:56 PM CDT on Wednesday, December 30th
 
Site Emergency procedures were activated and Technicians drained water out of instrument 
reservoirs and other measures as needed, early Monday morning.
 
On Wednesdays as roads and power started was restored to much of the areas east of I-35 , 
Site Technicians performed maintenance on several Extended Facilities.

During this period, data are potentially missing, incorrect, or suspect.  Carefully 
inspect the data before use.

MAO/AOS/CCN/CLAP/CPC/NEPHELOMETER/PSAP/M1 - Reprocess: Dilution flow calibration update

Dilution flow calibrations are incorrect. Dilution flow corrections need to be applied to 
b1 data.

Flow: 11.1 lpm 2015-02-19 04:19:12 to 2015-03-02 21:21:36 UTC
Flow: 9.75 lpm 2015-05-15 00:00:00 to 2015-07-01 23:59:59 UTC
Flow: 3.7178 slpm 2015-07-01 00:00:00 to 2015-11-08 23:59:59 UTC
Flow: 9.324 slpm 2015-11-08 00:00:00 UTC to 2015-12-01 23:59:59 UTC

SGP/AOS/C1 - Wildfire smoke plumes advecting over facility

Smoke from nearby wildfires advected through SGP C1 during the listed affected time 
ranges, resulting in high signals observable in many of the listed AOS datastreams.

• Aerosol total light scattering coefficient, reference nephelometer blue channel,
  1 um particle diameter(Bs_B_Wet_1um_Neph3W_2)
• T_postHG
• T_MainInlet
• RH_postHG
• Aerosol total light scattering coefficient, reference nephelometer blue channel,
  10 um particle diam(Bs_B_Dry_10um_Neph3W_1)
• Aerosol total light scattering coefficient, Humidograph nephelometer green
  channel, 10 um particle d(Bs_G_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, Ref. Humidograph nephelometer green
  channel, 1 um particle diameter(Bs_G_Dry_1um_Neph3W_1)
• Absorption coefficient red, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_R_Dry_10um_PSAP3W_1)
• Ambient pressure(P_Ambient)
• East longitude(lon)
• Aerosol total light scattering coefficient, reference nephelometer red channel,
  10 um particle diameter(Bs_R_Dry_10um_Neph3W_1)
• P_Neph_Dry
• T_NephVol_Dry
• RH_NephVol_Wet
• RH_NephVol_Dry
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer red channel, 1 um particle diameter(Bbs_R_Dry_1um_Neph3W_1)
• Absorption coefficient blue, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_B_Dry_1um_PSAP3W_1)
• Back-scattering coefficient, blue wavelength, low RH, 10 um size cut(Bbs_B_Dry_10um_Neph3W_1)
• Wind direction, relative to true North(WindDirection)
• Aerosol total light scattering coefficient, ref. humidograph nephelometer red
  channel, 1 um particle diameter(Bs_R_Dry_1um_Neph3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer red channel, 10 um particle diameter(Bbs_R_Dry_10um_Neph3W_1)
• Absorption coefficient, green wavelength, 3 wavelength PSAP, low RH, 10 um size
  cut(Ba_G_Dry_10um_PSAP3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer green channel,(Bbs_G_Wet_1um_Neph3W_2)
• Total scattering coefficient, blue wavelength, low RH, 1 um size cut(Bs_B_Dry_1um_Neph3W_1)
• T_NephInlet_Wet
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer green channel, 10(Bbs_G_Dry_10um_Neph3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer green channel,(Bbs_G_Wet_10um_Neph3W_2)
• Absorption coefficient, green wavelength, low RH, 1 um size cut(Ba_G_Dry_1um_PSAP1W_1)
• RH_preHG
• Condensation nuclei concentration number(N_CPC_1)
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer blue channel, 1 um particle diameter(Bbs_B_Wet_1um_Neph3W_2)
• Ambient air relative humidity(RH_Ambient)
• Absorption coefficient, green wavelength, low RH, 10 um size cut(Ba_G_Dry_10um_PSAP1W_1)
• time
• base_time
• Altitude above mean sea level(alt)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer red channel, 1(Bbs_R_Wet_1um_Neph3W_2)
• T_NephInlet_Dry
• P_Neph_Wet
• Absorption Coefficient Green, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_G_Dry_1um_PSAP3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer red channel, 10(Bbs_R_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, reference nephelometer red channel,
  10 um particle diameter(Bs_R_Wet_10um_Neph3W_2)
• Back-scattering coefficient, blue wavelength, low RH, 1 um size cut(Bbs_B_Dry_1um_Neph3W_1)
• RH_NephInlet_Wet
• Wind speed(WindSpeed)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer blue channel, 1(Bbs_B_Wet_10um_Neph3W_2)
• Absorption coefficient red, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_R_Dry_1um_PSAP3W_1)
• North latitude(lat)
• Aerosol total light scattering coefficient, reference nephelometer green
  channel, 1 um particle diameter(Bs_G_Wet_1um_Neph3W_2)
• RH_MainInlet
• Mean number concentration of N_CCN(N_CCN)
• RH_NephInlet_Dry
• T_NephVol_Wet
• Aerosol total light scattering coefficient, Humidograph nephelometer red
  channel, 1 um particle diam(Bs_R_Wet_1um_Neph3W_2)
• Aerosol backwards-hemispheric light scattering coefficient, Ref. Humidograph
  nephelometer green chan(Bbs_G_Dry_1um_Neph3W_1)
• Absorption coefficient blue, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_B_Dry_10um_PSAP3W_1)
• Aerosol total light scattering coefficient, Humidograph nephelometer blue
  channel, 10 um particle di(Bs_B_Wet_10um_Neph3W_2)
• Ambient air temperature(T_Ambient)
• flags_CMDL
• time_offset
• T_preHG
• Aerosol total light scattering coefficient, reference nephelometer green
  channel, 10 um particle diameter(Bs_G_Dry_10um_Neph3W_1)

• Absorption coefficient, green wavelength, low RH, 1 um size cut(Ba_G_Dry_1um_PSAP1W_1)
• Absorption coefficient red, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_R_Dry_1um_PSAP3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Ref. Humidograph
  nephelometer green chan(Bbs_G_Dry_1um_Neph3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer red channel, 1 um particle diameter(Bbs_R_Dry_1um_Neph3W_1)
• Wind direction, relative to true North(WindDirection)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer red channel, 10(Bbs_R_Wet_10um_Neph3W_2)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer green channel,(Bbs_G_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, Humidograph nephelometer green
  channel, 10 um particle d(Bs_G_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, reference nephelometer red channel,
  10 um particle diameter(Bs_R_Dry_10um_Neph3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer green channel,(Bbs_G_Wet_1um_Neph3W_2)
• RH_MainInlet
• Ambient air temperature(T_Ambient)
• Aerosol total light scattering coefficient, reference nephelometer red channel,
  10 um particle diameter(Bs_R_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, reference nephelometer blue channel,
  10 um particle diam(Bs_B_Dry_10um_Neph3W_1)
• Absorption coefficient, green wavelength, 3 wavelength PSAP, low RH, 10 um size
  cut(Ba_G_Dry_10um_PSAP3W_1)
• time_offset
• T_NephVol_Wet
• Ambient air relative humidity(RH_Ambient)
• Absorption Coefficient Green, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_G_Dry_1um_PSAP3W_1)
• time
• T_NephVol_Dry
• Aerosol total light scattering coefficient, ref. humidograph nephelometer red
  channel, 1 um particle diameter(Bs_R_Dry_1um_Neph3W_1)
• RH_NephVol_Wet
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer green channel, 10(Bbs_G_Dry_10um_Neph3W_1)
• T_postHG
• North latitude(lat)
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer blue channel, 1 um particle diameter(Bbs_B_Wet_1um_Neph3W_2)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer blue channel, 1(Bbs_B_Wet_10um_Neph3W_2)
• Wind speed(WindSpeed)
• Back-scattering coefficient, blue wavelength, low RH, 1 um size cut(Bbs_B_Dry_1um_Neph3W_1)
• flags_CMDL
• RH_NephVol_Dry
• Aerosol total light scattering coefficient, reference nephelometer blue channel,
  1 um particle diameter(Bs_B_Wet_1um_Neph3W_2)
• base_time
• RH_postHG
• Ambient pressure(P_Ambient)
• T_MainInlet
• Aerosol backwards-hemispheric light scattering coefficient, reference
  nephelometer red channel, 10 um particle diameter(Bbs_R_Dry_10um_Neph3W_1)
• T_preHG
• Aerosol total light scattering coefficient, Humidograph nephelometer blue
  channel, 10 um particle di(Bs_B_Wet_10um_Neph3W_2)
• Aerosol total light scattering coefficient, reference nephelometer green
  channel, 1 um particle diameter(Bs_G_Wet_1um_Neph3W_2)
• Absorption coefficient, green wavelength, low RH, 10 um size cut(Ba_G_Dry_10um_PSAP1W_1)
• Altitude above mean sea level(alt)
• Total scattering coefficient, blue wavelength, low RH, 1 um size cut(Bs_B_Dry_1um_Neph3W_1)
• Mean number concentration of N_CCN(N_CCN)
• RH_preHG
• Absorption coefficient red, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_R_Dry_10um_PSAP3W_1)
• East longitude(lon)
• Condensation nuclei concentration number(N_CPC_1)
• Aerosol total light scattering coefficient, Humidograph nephelometer red
  channel, 1 um particle diam(Bs_R_Wet_1um_Neph3W_2)
• P_Neph_Dry
• RH_NephInlet_Dry
• T_NephInlet_Dry
• T_NephInlet_Wet
• RH_NephInlet_Wet
• Absorption coefficient blue, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_B_Dry_1um_PSAP3W_1)
• time_bounds
• Cloud droplet concentration number from summation of condensation nuclei counter
  size bins(N_CCN_1)
• P_Neph_Wet
• Aerosol total light scattering coefficient, reference nephelometer green
  channel, 10 um particle diameter(Bs_G_Dry_10um_Neph3W_1)
• Back-scattering coefficient, blue wavelength, low RH, 10 um size cut(Bbs_B_Dry_10um_Neph3W_1)
• Absorption coefficient blue, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_B_Dry_10um_PSAP3W_1)
• Aerosol backwards-hemispheric light scattering coefficient, Humidograph
  nephelometer red channel, 1(Bbs_R_Wet_1um_Neph3W_2)
• Aerosol total light scattering coefficient, Ref. Humidograph nephelometer green
  channel, 1 um particle diameter(Bs_G_Dry_1um_Neph3W_1)

SGP/AOS/C1  - Annual Maintenance

The AOS Annual maintenance/calibration visit occurred during these periods.  During these 
times, instruments were cleaned, calibrated, and when necessary, repaired.  Instruments 
were online collecting data for some of the time; however, periods of contamination are 
probable because aerosol sampling lines were opened for inspection and cleaning and pumps 
were switched off for periods of time. Any data fields during this period that contain 
data should be considered incorrect.

• Particle concentration (0.50 um < Dp < 0.60 um) from PMS PCASP optical particle
  counter, channel 13(pa50_p60conc)
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• HGupstream_RH
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Particle concentration (2.00 um < Dp < 2.30 um) from PMS PCASP optical particle
  counter, channel 23(pa200_p230conc)
• Pres530nm
• HGdownstream_T
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• RH530nm
• Particle concentration (2.30 um < Dp < 2.60 um) from PMS PCASP optical particle
  counter, channel 24(pa230_p260conc)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Absorption coefficient at 10 um(Bap_I_10um)
• Particle concentration (0.70 um < Dp < 0.80 um) from PMS PCASP optical particle
  counter, channel 15(pa70_p80conc)
• Particle concentration (3.00 um < Dp < 3.50 um) from PMS PCASP optical particle
  counter, channel 26(pa300_p350conc)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Particle concentration (1.00 um < Dp < 1.30 um) from PMS PCASP optical particle
  counter, channel 18(pa100_p130conc)
• Particle concentration (0.20 um < Dp < 0.23 um) from PMS PCASP optical particle
  counter, channel 6(pa20_p23conc)
• TSINephRHSamp_HRH
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Particle concentration (0.45 um < Dp < 0.50 um) from PMS PCASP optical particle
  counter, channel 12(pa45_p50conc)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Backscattering coefficient at 530 nm from single wave nephelometer(Bscat530nm)
• Particle concentration (1.40 um < Dp < 1.60 um) from PMS PCASP optical particle
  counter, channel 20(pa140_p160conc)
• Particle concentration (0.14 um < Dp < 0.16 um) from PMS PCASP optical particle
  counter, channel 3(pa14_p16conc)
• TSINephTin_LRH
• Particle concentration from Condensation Particle Counter(CPCPartConc)
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Particle concentration (1.60 um < Dp < 1.80 um) from PMS PCASP optical particle
  counter, channel 21(pa160_p180conc)
• Particle concentration (3.50 um < Dp < 4.00 um) from PMS PCASP optical particle
  counter, channel 27(pa350_p400conc)
• Particle concentration (0.23 um < Dp < 0.26 um) from PMS PCASP optical particle
  counter, channel 7(pa23_p26conc)
• Absorption coefficient at 1 um(Bap_I_1um)
• TSINephTSamp_LRH
• Particle concentration (4.00 um < Dp < 5.00 um) from PMS PCASP optical particle
  counter, channel 28(pa400_p500conc)
• Particle concentration (0.60 um < Dp < 0.70 um) from PMS PCASP optical particle
  counter, channel 14(pa60_p70conc)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Particle concentration (0.26 um < Dp < 0.30 um) from PMS PCASP optical particle
  counter, channel 8(pa26_p30conc)
• TSINephPres_LRH
• Particle concentration (1.80 um < Dp < 2.00 um) from PMS PCASP optical particle
  counter, channel 22(pa180_p200conc)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Particle concentration (6.50 um < Dp < 8.00 um) from PMS PCASP optical particle
  counter, channel 30(pa650_p800conc)
• Particle concentration (0.30 um < Dp < 0.35 um) from PMS PCASP optical particle
  counter, channel 9(pa30_p35conc)
• Particle concentration (0.16 um < Dp < 0.18 um) from PMS PCASP optical particle
  counter, channel 4(pa16_p18conc)
• TSINephPres_HRH
• SampTemp
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• HGdownstream_RH
• SampRH
• Neph530Temp
• Ozone concentration(Ozone)
• Particle concentration (Dp > 10 um) from PMS PCASP optical particle counter,
  channel 0(Pa1000Conc)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• Particle concentration (0.10 um < Dp < 0.12 um) from PMS PCASP optical particle
  counter, channel 1(pa10_p12conc)
• Particle concentration (5.00 um < Dp < 6.50 um) from PMS PCASP optical particle
  counter, channel 29(pa500_p650conc)
• Particle concentration (2.60 um < Dp < 3.00 um) from PMS PCASP optical particle
  counter, channel 25(pa260_p300conc)
• AmbTemp
• HGupstream_T
• Particle concentration (0.40 um < Dp < 0.45 um) from PMS PCASP optical particle
  counter, channel 11(pa40_p45conc)
• Particle concentration (0.90 um < Dp < 1.00 um) from PMS PCASP optical particle
  counter, channel 17(pa90_p100conc)
• Particle concentration (0.12 um < Dp < 0.14 um) from PMS PCASP optical particle
  counter, channel 2(pa12_p14conc)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Particle concentration (8.00 um < Dp < 10.00 um) from PMS PCASP optical particle
  counter, channel 31(pa800_p1000conc)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• Particle concentration (1.30 um < Dp < 1.40 um) from PMS PCASP optical particle
  counter, channel 19(pa130_p140conc)
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Particle concentration (0.18 um < Dp < 0.20 um) from PMS PCASP optical particle
  counter, channel 5(pa18_p20conc)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH
• Particle concentration (0.80 um < Dp < 0.90 um) from PMS PCASP optical particle
  counter, channel 16(pa80_p90conc)
• Particle concentration (0.35 um < Dp < 0.40 um) from PMS PCASP optical particle
  counter, channel 10(pa35_p40conc)

SGP/AOS/C1 - Single wavelength nephelometer pump failure

The pump failed on the single-wavelength nephelometer line.  The vacuum gauge also failed, 
giving vacuum readings that made it appear that the pump was still working.  Technicians 
reported that the pump was still working during this period, although the vacuum gauge 
read slightly lower than expected.  The nephelometer was measuring aerosol scattering 
inside the scattering volume, which over time showed consistently low scattering values.  
This problem was difficult to diagnose given the faulty vacuum gauge and the fact that the 
site experienced relatively low ambient aerosol scattering values during this period.  The 
repair was made just prior to the AOS annual maintenance visit in April 1998.  The only 
field in the AOS data files that was affected was Field 29, "Bscat530nm".

• Backscattering coefficient at 530 nm from single wave nephelometer(Bscat530nm)

SGP/AOS/C1  - PSAP Flow Rate Change

The AOS PSAP flow rate was reduce due to data becoming noisy at the end of each weekend, 
probably due to the decrease in the dynamic range of the instrument experienced when the 
filter is heavily loaded.

The flow rate of the PSAP was decreased from its previous nominal value of 0.90 standard 
liters per minute to 0.75 standard liters per minute on 5/26/98 at 1910 GMT.  This should 
lessen the aerosol deposit buildup at the end of the weekends

• Particle concentration (0.50 um < Dp < 0.60 um) from PMS PCASP optical particle
  counter, channel 13(pa50_p60conc)
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• HGupstream_RH
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Particle concentration (2.00 um < Dp < 2.30 um) from PMS PCASP optical particle
  counter, channel 23(pa200_p230conc)
• Pres530nm
• HGdownstream_T
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• RH530nm
• Particle concentration (2.30 um < Dp < 2.60 um) from PMS PCASP optical particle
  counter, channel 24(pa230_p260conc)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Absorption coefficient at 10 um(Bap_I_10um)
• Particle concentration (0.70 um < Dp < 0.80 um) from PMS PCASP optical particle
  counter, channel 15(pa70_p80conc)
• Particle concentration (3.00 um < Dp < 3.50 um) from PMS PCASP optical particle
  counter, channel 26(pa300_p350conc)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Particle concentration (1.00 um < Dp < 1.30 um) from PMS PCASP optical particle
  counter, channel 18(pa100_p130conc)
• Particle concentration (0.20 um < Dp < 0.23 um) from PMS PCASP optical particle
  counter, channel 6(pa20_p23conc)
• TSINephRHSamp_HRH
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Particle concentration (0.45 um < Dp < 0.50 um) from PMS PCASP optical particle
  counter, channel 12(pa45_p50conc)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Backscattering coefficient at 530 nm from single wave nephelometer(Bscat530nm)
• Particle concentration (1.40 um < Dp < 1.60 um) from PMS PCASP optical particle
  counter, channel 20(pa140_p160conc)
• Particle concentration (0.14 um < Dp < 0.16 um) from PMS PCASP optical particle
  counter, channel 3(pa14_p16conc)
• TSINephTin_LRH
• Particle concentration from Condensation Particle Counter(CPCPartConc)
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Particle concentration (1.60 um < Dp < 1.80 um) from PMS PCASP optical particle
  counter, channel 21(pa160_p180conc)
• Particle concentration (3.50 um < Dp < 4.00 um) from PMS PCASP optical particle
  counter, channel 27(pa350_p400conc)
• Particle concentration (0.23 um < Dp < 0.26 um) from PMS PCASP optical particle
  counter, channel 7(pa23_p26conc)
• Absorption coefficient at 1 um(Bap_I_1um)
• TSINephTSamp_LRH
• Particle concentration (4.00 um < Dp < 5.00 um) from PMS PCASP optical particle
  counter, channel 28(pa400_p500conc)
• Particle concentration (0.60 um < Dp < 0.70 um) from PMS PCASP optical particle
  counter, channel 14(pa60_p70conc)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Particle concentration (0.26 um < Dp < 0.30 um) from PMS PCASP optical particle
  counter, channel 8(pa26_p30conc)
• TSINephPres_LRH
• Particle concentration (1.80 um < Dp < 2.00 um) from PMS PCASP optical particle
  counter, channel 22(pa180_p200conc)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Particle concentration (6.50 um < Dp < 8.00 um) from PMS PCASP optical particle
  counter, channel 30(pa650_p800conc)
• Particle concentration (0.30 um < Dp < 0.35 um) from PMS PCASP optical particle
  counter, channel 9(pa30_p35conc)
• Particle concentration (0.16 um < Dp < 0.18 um) from PMS PCASP optical particle
  counter, channel 4(pa16_p18conc)
• TSINephPres_HRH
• SampTemp
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• HGdownstream_RH
• SampRH
• Neph530Temp
• Ozone concentration(Ozone)
• Particle concentration (Dp > 10 um) from PMS PCASP optical particle counter,
  channel 0(Pa1000Conc)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• Particle concentration (0.10 um < Dp < 0.12 um) from PMS PCASP optical particle
  counter, channel 1(pa10_p12conc)
• Particle concentration (5.00 um < Dp < 6.50 um) from PMS PCASP optical particle
  counter, channel 29(pa500_p650conc)
• Particle concentration (2.60 um < Dp < 3.00 um) from PMS PCASP optical particle
  counter, channel 25(pa260_p300conc)
• AmbTemp
• HGupstream_T
• Particle concentration (0.40 um < Dp < 0.45 um) from PMS PCASP optical particle
  counter, channel 11(pa40_p45conc)
• Particle concentration (0.90 um < Dp < 1.00 um) from PMS PCASP optical particle
  counter, channel 17(pa90_p100conc)
• Particle concentration (0.12 um < Dp < 0.14 um) from PMS PCASP optical particle
  counter, channel 2(pa12_p14conc)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Particle concentration (8.00 um < Dp < 10.00 um) from PMS PCASP optical particle
  counter, channel 31(pa800_p1000conc)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• Particle concentration (1.30 um < Dp < 1.40 um) from PMS PCASP optical particle
  counter, channel 19(pa130_p140conc)
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Particle concentration (0.18 um < Dp < 0.20 um) from PMS PCASP optical particle
  counter, channel 5(pa18_p20conc)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH
• Particle concentration (0.80 um < Dp < 0.90 um) from PMS PCASP optical particle
  counter, channel 16(pa80_p90conc)
• Particle concentration (0.35 um < Dp < 0.40 um) from PMS PCASP optical particle
  counter, channel 10(pa35_p40conc)

SGP/AOS/C1  - Single-wavelength nephelometer errors

Due to a malfunctioning bypass valve, the single wavelength nephelometer was not properly 
sampling ambient air.  Thus, scattering values during this period are incorrect.  The 
incorrect data field is "Bscat530nm".

• Backscattering coefficient at 530 nm from single wave nephelometer(Bscat530nm)

SGP/AOS/C1 - 3-wavelength nephelometer failure

The backscatter shutter on the TSI 3-wavelength nephelometer failed and
the unit had to be replaced.  Data are either missing or incorrect.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• TSINephPres_HRH
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - Condensation Particle Counter failure

During the time periods specified, the AOS Condensation Particle Counter was down for 
maintenance.

• Particle concentration from Condensation Particle Counter(CPCPartConc)

SGP/AOS/C1 - Optical Particle Counter (PCASP-X) down

The AOS Optical Particle Spectrometer (PCASP-X sizing probe) was down during these 
periods.  This lowers the laser reference voltage and results in inaccurate sizing.

• Particle concentration (0.50 um < Dp < 0.60 um) from PMS PCASP optical particle
  counter, channel 13(pa50_p60conc)
• Particle concentration (1.80 um < Dp < 2.00 um) from PMS PCASP optical particle
  counter, channel 22(pa180_p200conc)
• Particle concentration (6.50 um < Dp < 8.00 um) from PMS PCASP optical particle
  counter, channel 30(pa650_p800conc)
• Particle concentration (2.00 um < Dp < 2.30 um) from PMS PCASP optical particle
  counter, channel 23(pa200_p230conc)
• Particle concentration (0.30 um < Dp < 0.35 um) from PMS PCASP optical particle
  counter, channel 9(pa30_p35conc)
• Particle concentration (0.16 um < Dp < 0.18 um) from PMS PCASP optical particle
  counter, channel 4(pa16_p18conc)
• Particle concentration (2.30 um < Dp < 2.60 um) from PMS PCASP optical particle
  counter, channel 24(pa230_p260conc)
• Particle concentration (3.00 um < Dp < 3.50 um) from PMS PCASP optical particle
  counter, channel 26(pa300_p350conc)
• Particle concentration (0.70 um < Dp < 0.80 um) from PMS PCASP optical particle
  counter, channel 15(pa70_p80conc)
• Particle concentration (1.00 um < Dp < 1.30 um) from PMS PCASP optical particle
  counter, channel 18(pa100_p130conc)
• Particle concentration (0.20 um < Dp < 0.23 um) from PMS PCASP optical particle
  counter, channel 6(pa20_p23conc)
• Particle concentration (Dp > 10 um) from PMS PCASP optical particle counter,
  channel 0(Pa1000Conc)
• Particle concentration (0.45 um < Dp < 0.50 um) from PMS PCASP optical particle
  counter, channel 12(pa45_p50conc)
• Particle concentration (0.10 um < Dp < 0.12 um) from PMS PCASP optical particle
  counter, channel 1(pa10_p12conc)
• Particle concentration (5.00 um < Dp < 6.50 um) from PMS PCASP optical particle
  counter, channel 29(pa500_p650conc)
• Particle concentration (2.60 um < Dp < 3.00 um) from PMS PCASP optical particle
  counter, channel 25(pa260_p300conc)
• Particle concentration (1.40 um < Dp < 1.60 um) from PMS PCASP optical particle
  counter, channel 20(pa140_p160conc)
• Particle concentration (0.14 um < Dp < 0.16 um) from PMS PCASP optical particle
  counter, channel 3(pa14_p16conc)
• Particle concentration (0.40 um < Dp < 0.45 um) from PMS PCASP optical particle
  counter, channel 11(pa40_p45conc)
• Particle concentration (0.90 um < Dp < 1.00 um) from PMS PCASP optical particle
  counter, channel 17(pa90_p100conc)
• Particle concentration (1.60 um < Dp < 1.80 um) from PMS PCASP optical particle
  counter, channel 21(pa160_p180conc)
• Particle concentration (3.50 um < Dp < 4.00 um) from PMS PCASP optical particle
  counter, channel 27(pa350_p400conc)
• Particle concentration (0.12 um < Dp < 0.14 um) from PMS PCASP optical particle
  counter, channel 2(pa12_p14conc)
• Particle concentration (0.23 um < Dp < 0.26 um) from PMS PCASP optical particle
  counter, channel 7(pa23_p26conc)
• Particle concentration (8.00 um < Dp < 10.00 um) from PMS PCASP optical particle
  counter, channel 31(pa800_p1000conc)
• Particle concentration (1.30 um < Dp < 1.40 um) from PMS PCASP optical particle
  counter, channel 19(pa130_p140conc)
• Particle concentration (4.00 um < Dp < 5.00 um) from PMS PCASP optical particle
  counter, channel 28(pa400_p500conc)
• Particle concentration (0.18 um < Dp < 0.20 um) from PMS PCASP optical particle
  counter, channel 5(pa18_p20conc)
• Particle concentration (0.60 um < Dp < 0.70 um) from PMS PCASP optical particle
  counter, channel 14(pa60_p70conc)
• Particle concentration (0.26 um < Dp < 0.30 um) from PMS PCASP optical particle
  counter, channel 8(pa26_p30conc)
• Particle concentration (0.80 um < Dp < 0.90 um) from PMS PCASP optical particle
  counter, channel 16(pa80_p90conc)
• Particle concentration (0.35 um < Dp < 0.40 um) from PMS PCASP optical particle
  counter, channel 10(pa35_p40conc)

SGP/AOS/C1 - Instrument communications problems

Several of the AOS instruments apparently lost communications with the AOS computer during 
this period.  These instruments were the TSI 3-wavelength nephelometer, the PSAP light 
absorption photometer, and the Dasibi ozone instrument.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Absorption coefficient at 10 um(Bap_I_10um)
• TSINephPres_HRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Ozone concentration(Ozone)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Absorption coefficient at 1 um(Bap_I_1um)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - 3-wavelength nephelometer data missing

The AOS TSI 3-wavelength nephelometer lost communications with the AOS data system during 
this period.  Cause of the communications break is unknown.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Pres530nm
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• RH530nm
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• TSINephPres_HRH
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Neph530Temp
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - Ozone instrument left in span mode

AOS Ozone instrument was left in span mode over the weekend.  Span value was logged during 
this period.

• Ozone concentration(Ozone)

SGP/AOS/C1 - Line 8 bypass in wrong position

The Line 8 bypass valve was stuck in the wrong position.  Consequently, air was not being 
drawn through the TSI 3-wavelength nephelometer and the PSAP light absorption photometer, 
and thus they were not measuring ambient (outdoor) aerosols.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Absorption coefficient at 10 um(Bap_I_10um)
• TSINephPres_HRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Absorption coefficient at 1 um(Bap_I_1um)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - Light absorption photometer (PSAP) error

The AOS continuous light absorption photometer (PSAP) showed inaccurate data during this 
period due to a filter being inserted into the optical assembly incorrectly.

• Absorption coefficient at 10 um(Bap_I_10um)
• Absorption coefficient at 1 um(Bap_I_1um)

SGP/AOS/C1 - Ozone Instrument Communication Failure

The AOS Ozone instrument apparently lost communications with the AOS computer during these 
periods.

• Ozone concentration(Ozone)

SGP/AOS/C1 - Ozone Instrument data incorrect

A filter of the wrong type was placed in the ozone instrument intake line.  This filter 
destroys ozone, and consequently the measured ozone values during this period are 
abnormally low.

• Ozone concentration(Ozone)

SGP/AOS/C1 - Aerosol sampling system and nephelometer failure

The electronic valve that switches the aerosol sampling system from sampling the total 
aerosol (D<10 um) to the submicrometer (D<1 um) aerosol began having intermittent 
positioning problems.  All 3-wavelength nephelometer and light absorption photometer data collected 
during this time period should be viewed as suspect, since we can't be sure what 
particle size range was being sampled at any time.  During this interval, the nephelometer lamp 
became unstable and finally blew, giving no nephelometer data for the end of this period. 
 The period of lamp failure in the AOS data files can be recognized by prolonged periods 
of missing value codes for aerosol scattering and nephelometer housekeeping channels.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Pres530nm
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• RH530nm
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Absorption coefficient at 10 um(Bap_I_10um)
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• TSINephPres_HRH
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Neph530Temp
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Absorption coefficient at 1 um(Bap_I_1um)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - 3-wavelength nephelometer data missing

The AOS data system lost communications initially with the 3-wavelength TSI nephelometer.  
A communications port on the Sun workstation became locked, and attempts to unlock it 
were unsuccesful.  Stopping and restarting the data collection software did not solve the 
problem. Missing value codes were being generated for all TSI nephelometer measurements 
and parameters.  The decision was made to reboot the workstation.  On 981110, at 1555 GMT, 
the workstation was rebooted.  We discovered then that we did not have the proper root 
user password to log back onto the system and restart the software.  From 981110 (1555GMT) 
to 981112 (0501GMT) no data were being logged by the AOS data system.

• TSINephPres_LRH
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• TSINephTSamp_HRH
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Pres530nm
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• RH530nm
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• TSINephRHSamp_LRH
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• TSINephPres_HRH
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• TSINephRHSamp_HRH
• Neph530Temp
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• TSINephTin_LRH
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• TSINephTSamp_LRH
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• TSINephTin_HRH

SGP/AOS/C1 - Intermittent leak in AOS spare sampling line and thermal sensitivity

Starting on 980619, periodic fluctuations in several of the measured AOS parameters (e.g., 
Aerosol light absorption coefficent, TSI nephelometer relative humidity, condensation 
particle counts, etc.) were observed. The start of these fluctuations coincided exactly 
with the shutdown of the AOS for power washing of the wooden stairs and stack platform.  
Numerous attempts at troubleshooting were conducted via telephone with technicians at the site.
 
These concentrated on 1) trying to find an electrical noise problem or 2) determining 
whether our stack heating unit was somehow producing particles. Tests were devised to check 
both of these possibilities, and both were determined to be non-problems.  The 
troubleshooting of this signal fluctuation problem was compounded and delayed by the concurrent 
unrelated electronic ball valve problem (see AOS DQR#980731.1).

Pat Sheridan and Jim Wendell from the NOAA Aerosols Group went to the SGP Central Facility 
to diagnose and repair the problem.  All electromagnetic noise possibilities, including 
bad grounds and RF fields were checked. These were not causing the fluctuations, which 
varied in period from ~15-30 minutes. Upon dismantling the insulated air intake assembly 
inside the trailer, a minute crack was found in one of the spare sampling lines at its 
connection to the manifold.  This line was one of the original installed by the previous mentor. 

Repair of this line break essentially repaired the fluctuation problem, although this 
extensive troubleshooting revealed a slight temperature dependence for some of our reference 
signals (more on this below).

Our explanation of this problem is as follows.  When the AOS stairs were power washed, 
either the activities associated with power washing (e.g. people or compressors on the 
platform) or lowering the stack caused enough vibration to cause a hairline break in the spare 
sampling line at the connection with the manifold.  We believe this tubing is 
high-density polyethylene, which is semi-rigid, and it has now been replaced with less brittle 
material.  The routine daily system zero checks established by the previous mentor would not 
have detected this leak problem, because overpressurization of the manifold with 
particle-free air showed up as good zero checks in all instruments and some of this clean air 
would have simply flowed out of the spare line tubing crack.  Since the crack was beneath at 
least two layers of foam insulation which itself was covered with foam-backed metallic 
tape, we believe that free air flow of trailer air to the crack was not likely.  However, 
during periods when the large air conditioning unit was on, pressurization of the trailer 
caused air to slowly leak into the spare sampling line and back into the manifold and 
other sampling lines.  Upon arrival at the site, we found the fan for the A/C system 
operating only when the A/C compressor came on.  We were informed by Dan Nelson, Site Engineer, 
that this fan is supposed to stay on all the time.  Our data suggest that this fan has 
been off since before the problem began.  This is fortuitous, because the trailer was not 
continually pressurized and room air was not sampled continuously over this period.  
Thus, only a portion of the data are of questionable quality.  This leak was not immediately 
obvious (to AOS technicians or to us) because of its concealed location and because some 
aerosol measurements (e.g., particle number concentrations, aerosol light absorption 
coefficents, etc.) did not change dramatically during these periods (i.e., the aerosols 
brought inside the trailer through the cooling system were often not much different in 
concentration or optical properties than were aerosols sampled at the top of the stack).  Thus 
data during the A/C periods will be labeled as questionable.

We will institute a new leak check/zero check procedure which should catch leaks of this 
type.  The old system zero check devised by the previous mentor was insufficient to find 
this leak. 

The A/C unit in the AOS trailer is more than adequate to cool that space.  The cold air 
that comes out of the vents is probably >20F cooler than trailer air.  This cold air causes 
slight fluctuations in the lamp voltages and reference signals of several of our 
instruments.  We expect this problem to be more severe in the summertime because of increased 
air conditioner use and indoor temperature swings.  Fortunately, these signal fluctuations 
are not observed in the final processed signals from these instruments.  They do, 
however, suggest that a gentler cooling of the trailer should be considered.

Possibilities for this could include:
1)	Installation of a smaller air conditioning unit
2)	Changing the ratio of outside air mixed in with the cooled air
3)	Venting the exhaust from the cabinets into the air recirculating 
        system to preheat the cooled air.

We realize that these suggestions may not be in line with the notion of efficient cooling 
of the trailer.  However, we feel that the root cause of the observed temperature 
fluctuations is that the air conditioning unit has far more capacity than is needed by the AOS 
trailer.  A smaller air conditioner, properly matched to the heat load of the trailer, 
would probably be a more efficient solution.

Since the cooling of the trailer generally was faster than the warming-up period, a 
majority of data should be valid.  Also, not all measurements appeared questionable (i.e., the 
data did not appear to change when the A/C unit came on).  We have flagged all aerosol 
data as "questionable" during A/C "on" periods because of the likelihood that at least some 
mixing of trailer air with ambient air occurred.

• Particle concentration (0.50 um < Dp < 0.60 um) from PMS PCASP optical particle
  counter, channel 13(pa50_p60conc)
• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Particle concentration (2.00 um < Dp < 2.30 um) from PMS PCASP optical particle
  counter, channel 23(pa200_p230conc)
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• Particle concentration (2.30 um < Dp < 2.60 um) from PMS PCASP optical particle
  counter, channel 24(pa230_p260conc)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Absorption coefficient at 10 um(Bap_I_10um)
• Particle concentration (0.70 um < Dp < 0.80 um) from PMS PCASP optical particle
  counter, channel 15(pa70_p80conc)
• Particle concentration (3.00 um < Dp < 3.50 um) from PMS PCASP optical particle
  counter, channel 26(pa300_p350conc)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Particle concentration (1.00 um < Dp < 1.30 um) from PMS PCASP optical particle
  counter, channel 18(pa100_p130conc)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Particle concentration (0.20 um < Dp < 0.23 um) from PMS PCASP optical particle
  counter, channel 6(pa20_p23conc)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Particle concentration (0.45 um < Dp < 0.50 um) from PMS PCASP optical particle
  counter, channel 12(pa45_p50conc)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Backscattering coefficient at 530 nm from single wave nephelometer(Bscat530nm)
• Particle concentration (1.40 um < Dp < 1.60 um) from PMS PCASP optical particle
  counter, channel 20(pa140_p160conc)
• Particle concentration (0.14 um < Dp < 0.16 um) from PMS PCASP optical particle
  counter, channel 3(pa14_p16conc)
• Particle concentration from Condensation Particle Counter(CPCPartConc)
• Particle concentration (1.60 um < Dp < 1.80 um) from PMS PCASP optical particle
  counter, channel 21(pa160_p180conc)
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Particle concentration (3.50 um < Dp < 4.00 um) from PMS PCASP optical particle
  counter, channel 27(pa350_p400conc)
• Particle concentration (0.23 um < Dp < 0.26 um) from PMS PCASP optical particle
  counter, channel 7(pa23_p26conc)
• Absorption coefficient at 1 um(Bap_I_1um)
• Particle concentration (4.00 um < Dp < 5.00 um) from PMS PCASP optical particle
  counter, channel 28(pa400_p500conc)
• Particle concentration (0.60 um < Dp < 0.70 um) from PMS PCASP optical particle
  counter, channel 14(pa60_p70conc)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Particle concentration (0.26 um < Dp < 0.30 um) from PMS PCASP optical particle
  counter, channel 8(pa26_p30conc)
• Particle concentration (1.80 um < Dp < 2.00 um) from PMS PCASP optical particle
  counter, channel 22(pa180_p200conc)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Particle concentration (6.50 um < Dp < 8.00 um) from PMS PCASP optical particle
  counter, channel 30(pa650_p800conc)
• Particle concentration (0.30 um < Dp < 0.35 um) from PMS PCASP optical particle
  counter, channel 9(pa30_p35conc)
• Particle concentration (0.16 um < Dp < 0.18 um) from PMS PCASP optical particle
  counter, channel 4(pa16_p18conc)
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Ozone concentration(Ozone)
• Particle concentration (Dp > 10 um) from PMS PCASP optical particle counter,
  channel 0(Pa1000Conc)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Particle concentration (0.10 um < Dp < 0.12 um) from PMS PCASP optical particle
  counter, channel 1(pa10_p12conc)
• Particle concentration (5.00 um < Dp < 6.50 um) from PMS PCASP optical particle
  counter, channel 29(pa500_p650conc)
• Particle concentration (2.60 um < Dp < 3.00 um) from PMS PCASP optical particle
  counter, channel 25(pa260_p300conc)
• Particle concentration (0.40 um < Dp < 0.45 um) from PMS PCASP optical particle
  counter, channel 11(pa40_p45conc)
• Particle concentration (0.90 um < Dp < 1.00 um) from PMS PCASP optical particle
  counter, channel 17(pa90_p100conc)
• Particle concentration (0.12 um < Dp < 0.14 um) from PMS PCASP optical particle
  counter, channel 2(pa12_p14conc)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Particle concentration (8.00 um < Dp < 10.00 um) from PMS PCASP optical particle
  counter, channel 31(pa800_p1000conc)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• Particle concentration (1.30 um < Dp < 1.40 um) from PMS PCASP optical particle
  counter, channel 19(pa130_p140conc)
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Particle concentration (0.18 um < Dp < 0.20 um) from PMS PCASP optical particle
  counter, channel 5(pa18_p20conc)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)
• Particle concentration (0.80 um < Dp < 0.90 um) from PMS PCASP optical particle
  counter, channel 16(pa80_p90conc)
• Particle concentration (0.35 um < Dp < 0.40 um) from PMS PCASP optical particle
  counter, channel 10(pa35_p40conc)

SGP/AOS/C1 - Ozone Instrument Failure

A malfunction occurred with the AOS surface ozone instrument during the period 990507 1556 
GMT to 990514 1445 GMT.  The instrument reported an ozone concentration of 9.91e-01 ppm 
(991 ppb) continuously during this time.  Quality checking of the data the following week 
revealed that the problem began at about the time weekly maintenance check was made on 
Friday.  The problem continued until the next weekly maintenance check was done.  Site Ops 
was notified by the mentor of the problem on Friday, 5/14/99, and a technician was sent 
to inspect the system.  No switches on the instrument front panel were found in the wrong 
position (for example, if the instrument was inadvertantly left in a calibration mode).  
By the time the technician arrived at the trailer, the instrument appeared to be working 
correctly.  No explanation is given as to why these erroneous values were being 
generated by the ozone instrument, except that possibly it locked up with the throwing of the 
weekly preventative maintenance switch and this problem was not corrected until the same 
switch was thrown the following week.

• Ozone concentration(Ozone)

SGP/AOS/C1 - Invalid absorption data

During the period noted, a valve position error with the 1-um/10-um impactor switching 
valve occurred.  The result of this error was to invalidate all switched data.  The software 
correctly inserted missing value codes in the nephelometer data, but the PSAP light 
absorption photometer for some reason reported a constant value over this period.

• Absorption coefficient at 10 um(Bap_I_10um)
• Absorption coefficient at 1 um(Bap_I_1um)

SGP/AOS/C1 - Incorrect absorption and scattering data

The electronically switched valve that alternately switches flow through 1-um and 10-um 
impactors showed an error during this time period.  This error invalidated all downstream 
data.  In the raw data files, aerosol light scattering coefficients for the TSI reference 
and humidified nephelometers were assigned missing value codes.  The aerosol light 
absorption coefficient was observed to stick at a constant value over this period.  The problem 
went away after the weekly maintenance was performed, although nothing specific was done 
to the valve.  The flipping of the maintenance switch appears to have solved the problem.

• Total scattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_1um_LRH)
• Backscattering coefficient at 10 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI Low RH Nephelometer(BluBScatCoef_1um_LRH)
• Backscattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_1um_LRH)
• Total scattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_1um_HRH)
• Absorption coefficient at 10 um(Bap_I_10um)
• Backscattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 550 nm TSI High RH Nephelometer(GrnBScatCoef_1um_HRH)
• Total scattering coefficient at 10 um from 550 nm TSI High RH Nephelometer(GrnTScatCoef_10um_HRH)
• Total scattering coefficient at 1 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 450 nm TSI High RH Nephelometer(BluTScatCoef_10um_HRH)
• Total scattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedTScatCoef_10um_LRH)
• Total scattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnTScatCoef_10um_LRH)
• Total scattering coefficient at 1 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_1um_HRH)
• Backscattering coefficient at 1 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_10um_LRH)
• Absorption coefficient at 1 um(Bap_I_1um)
• Backscattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedBScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 550 nm TSI Low RH Nephelometer(GrnBScatCoef_10um_LRH)
• Backscattering coefficient at 10 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_10um_HRH)
• Backscattering coefficient at 1 um, from 450 nm TSI High RH Nephelometer(BluBScatCoef_1um_HRH)
• Total scattering coefficient at 1 um from 450 nm TSI Low RH Nephelometer(BluTScatCoef_1um_LRH)
• Total scattering coefficient at 10 um from 700 nm TSI High RH Nephelometer(RedTScatCoef_10um_HRH)
• Backscattering coefficient at 10 um from 700 nm TSI Low RH Nephelometer(RedBScatCoef_10um_LRH)

SGP/AOS/C1 - Ozone instrument error

A switch on the front panel of the ozone instrument was left in the wrong position.  This 
resulted in a bad value for ozone concentration being logged for these periods.

• Ozone concentration(Ozone)