TWP/SKYRAD/C2 - Solar tracker failure

The solar tracker malfunctioned and did not track the sun reliably during the specified 
periods.  PIR, PSP, and NIP data are suspect.

The solar tracker may have operated satisfactorily during some periods within these time 
frames. Approximate verification on quality could be made by comparing the NIP data with 
the MFRSR data.

• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrgeometer(short_direct_normal)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Standard
  Deviation(down_long_hemisp_shaded_std)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer(down_long_hemisp_shaded)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)

• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2(down_long_hemisp2)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance, Pyrgeometer(short_direct_normal)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Standard Deviation(down_long_hemisp2_std)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Standard Deviation(down_short_diffuse_hemisp_std)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Minima(down_short_diffuse_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Maxima(short_direct_normal_max)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Maxima(down_long_hemisp2_max)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Minima(down_long_hemisp2_min)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer,
  Maxima(down_short_diffuse_hemisp_max)

• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_case_resist)
• Instantaneous Downwelling Pyrgeometer Thermopile Voltage, Shaded Pyrgeometer(inst_down_long_hemisp_shaded_tp)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_resist)

TWP/SKYRAD/C2 - Reprocess: PIR identified as unshaded is really shaded

On 17Sep01 the Global PIR was moved from the unshaded position on the Skyrad stand to the 
new 'shaded' spot on the new K&Z tracker. It is still using the same Logger channel as it 
did as an unshaded PIR even though it is now shaded.

• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Maxima(down_long_hemisp2_max)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_case_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2(down_long_hemisp2)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Minima(down_long_hemisp2_min)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Pyrgeometer2(inst_down_long_hemisp2_dome_temp)
• Downwelling Longwave Hemispheric Irradiance, Pyrgeometer2, Standard Deviation(down_long_hemisp2_std)
• Instantaneous Downwelling Pyrgeometer Thermopile, Pyrgeometer2(inst_down_long_hemisp2_tp)

TWP/SMET/C2 - Upper wind sensor failed

The upper wind speed sensor failed.  Wind speeds were reported as 0 m/s and wind direction 
data was not in agreement with the lower wind sensor. Anemometer was replaced.

• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Upper sensor, wind speed vector average(up_spd_vec_avg)

TWP/GNDRAD/C2 - IRT problem

The GNDRAD IRT exhibited a positive bias compared to the PIR from 2100 to 0700 UTC each 
day. The problem was corrected by removing the signal cable, cleaning the contacts, and 
reconnecting the cable.

• Surface Infra-Red Temperature, Standard Deviation(sfc_ir_temp_std)
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)

TWP/SKYRAD/C2  - IRT incorrect min/delta values

For field sky_ir_temp, the value of valid_min was incorrectly assigned to -49.7 C and no 
value of valid_delta was assigned. The actual values should be -60 and 50 C, respectively.

• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SMET/C2 - Lower wind sensor failure

The lower wind sensor failed.  Wind direction showed little or no variation, unlike the 
co-located/upper sensor.  This caused depressed wind speed values as the sensor was not 
rotating properly to orient itself parallel to the wind stream.  The sensor was replaced.

• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed minimum(lo_spd_min)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Lower sensor, wind direction standard deviation(lo_dir_sd)

TWP/SMET/C2 - connection and timing issues with new logger

Atmospheric pressure data are intermittent during this time period due to connection 
problems and program timing issues with new logger installation.  Data resumed normal 
operations after this time period.

• Barometric Pressure(atmos_pressure)

TWP/SMET/C2 - Negative rainfall rates

Due to limitations of the Zeno dataloggers all voltage measurements
from the optical rain gauge (ORG) were converted to rainfall rates. 
This resulted in negative values for rain rates.  Any value below
0.10 mm/hr should be considered to be 0 mm/hr.  New dataloggers 
alleviated this problem.

• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation maximum(precip_max)
• Precipitation standard deviation(precip_sd)

TWP/SMET/C2 - Incorrect rainrate equation used.

There are two different Optical Raingages in use at the TWP sites.  The incorrect equation 
was used at this site.  The incorrect equation is (25*(V^1.87)) - 0.15.
The correct equation is (20*(V^2)) - 0.05.  The correct equation was installed.

• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation maximum(precip_max)
• Precipitation standard deviation(precip_sd)

TWP/GNDRAD/C2 - incorrect IRT calibration

When the GNDRAD data logger was upgraded, the calibration offset for the IRT was initially 
incorrect.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)

TWP/SKYRAD/C2 - IRT bias

The IRT appears to be measuring higher sky temperatures than the AERI. There is no 
indication as to its cause or whether the IRT or the AERI is at fault.

PRB note: because the AERI is calibrated between each sample, the AERI
data has a high degree of confidence and the bias is likely on the part
of the IRT.

• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SKYRAD/C2 - IRT bias

The IRT was measuring higher sky temperatures than AERI. The problem was corrected by 
changing the mirror.

• Sky Infra-Red Temperature(sky_ir_temp)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SMET/C2 - Upper wind direction sensor failure

The upper wind direction sensor failed. Wind direction was reported at a near constant 
value of 69 degrees and was significantly different than the lower wind sensor's direction 
values. Sensor replaced.

• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind direction standard deviation(up_dir_sd)

TWP/SMET/C2 - Upper wind direction sensor failure

After replacement on 03/03/2005 the upper wind direction sensor began reporting erroneous 
values again on 03/09/2005 becoming very apparent after 03/17/2005.  Wind speed data 
appears reasonable but the wind direction data do not agree well with the lower wind sensor.

• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind direction standard deviation(up_dir_sd)

TWP/GNDRAD/C2 - IRT connector

The IRT had a problem with the connector of either the signal or power cable which 
produced an output of 0 volts equivalent to a measurement of 223K. The problem was corrected 
when the connectors were cleaned and tightened.

• Surface Infra-Red Temperature, Standard Deviation(sfc_ir_temp_std)
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)

TWP/SMET/C2 - RH sensor failure

Relative humidity values were frequently over MAX value of 104% starting on 7/10/2005 
through end of period.  Sensor was replaced.

• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Mean Relative Humidity(relh_mean)

TWP/SMET/C2 - Instrument maintenance

Instrument calibration and testing were taking place for brief periods.

• Vapor pressure standard deviation(vappress_sd)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Vapor pressure mean(vappress_mean)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind speed maximum(up_spd_max)
• Mean Air Temperature or Hardware Error(temp_mean)
• Tipping bucket raingauge count total(tbrg_count_total)
• Precipitation maximum(precip_max)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Lower sensor, wind speed minimum(lo_spd_min)
• Std Dev of Air Temperature(temp_sd)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Precipitation standard deviation(precip_sd)
• Barometric Pressure(atmos_pressure)
• Lower sensor, wind direction standard deviation(lo_dir_sd)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• precipitation minimum(precip_min)
• Precipitation mean(precip_mean)
• Tipping bucket raingauge total(tbrg_total)
• Mean Relative Humidity(relh_mean)
• Lower sensor, wind speed maximum(lo_spd_max)
• Upper sensor, wind speed standard deviation(up_spd_sd)

TWP/SMET/C2 - ORG data incorrect

Data from the ORG was incorrect due to heavy condensation on the lens.

• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation maximum(precip_max)
• Precipitation standard deviation(precip_sd)

TWP/SMET/C2 - Temp/RH probe failure

Temperature/RH probe failed and was replaced.

• Vapor pressure standard deviation(vappress_sd)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Std Dev of Air Temperature(temp_sd)
• Vapor pressure mean(vappress_mean)
• Mean Relative Humidity(relh_mean)
• Mean Air Temperature or Hardware Error(temp_mean)

TWP/GNDRAD/C2 - Reprocess: Longwave Calibration error

Modified pyrgeometer calibration procedures were implemented beginning in December 2003.  
These modified procedures introduced a calibration bias in the longwave data.  The 
previous procedures were re-implemented at all sites between December 2005 and February 2006 to 
restore proper calibrations.                                                             
                The data collected while the incorrect procedures were in place are 
being reprocessing to remove the calibration bias.  Note, this also affected standard 
deviation, maximum and minimum data fields.

• Upwelling (10 meter) Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)

TWP/SKYRAD/C2 - IRT signal loss

There was a significant drop in logger voltage that corresponds with a loss of the IR 
temperature. This was possibly due to a loose connection.

• Sky Infra-Red Temperature(sky_ir_temp)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SMET/C2 - Reprocess: Barometric pressure units change

Barometric pressure data during this time period is reported in hPa.  After this time, the 
data have been converted to kPa to standardize the measurement units among ARM sites and 
to conform to accepted standard units determined by the scientific community.

• Barometric Pressure(atmos_pressure)

TWP/SMET/C2 - Reprocess: Tipping bucket rain gauge added

A tipping bucket rain gauge was added to the TWP.C2 SMET suite of instruments on 20061129. 
Effective 20060926, two new variables (count and rain amount) were added to the end of 
the twpsmet60sC2.b1 datastream.  Between 9/26 and 11/29, the data for these two variables 
are filled with zeros.  Users should not use the data during this period as the zeros are 
not representative of the rain fall at the site.  When reprocessing of this datastream 
occurs these variables will be added for the 19981021-20060926 and data from 
19981021-20061129 will be filled with -9999 (missing).

• base time(base_time)

TWP/SKYRAD/C2 - IRT signal

The IRT exhibited a bias of the analog voltage output that caused problems with the 
signals from the other SKYRAD radiometers. The bias was due to corrosion between the power and 
signal connections in the IRT cable. The IRT was disconnected on 10/18/2006 at 01:20 and 
replaced on 11/6/2006 at 23:00 but it too appeared to have grounding problems due to 
internal corrosion and was disconnected on 11/11/2006 at 11:42 and then intermittently 
reconnected for testing. A second spare was installed on 12/4/2006 which did not cause problems 
with the signals from the other instruments.

• Sky Infra-Red Temperature(sky_ir_temp)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SMET/C2 - Barometer failure

The barometer began experiencing problems with noise resulting in incorrect data.  The 
problem becames worse over time; after 12/19/2006 @0151 GMT the barometer data is completely 
missing.  The barometer was replaced.

• Barometric Pressure(atmos_pressure)

TWP/GNDRAD/C2 - IRT signal

When the other GNDRAD radiometers were replaced on 12/3/2006, the quality of the IRT 
signal began to degrade until 12/26 when it became unusable. The instrument was replaced on 
2/4/2007.

• Surface Infra-Red Temperature, Standard Deviation(sfc_ir_temp_std)
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)

TWP/SKYRAD/C2 - IRT measurement error

The IRT was not properly calibrated and was not able to measure sky temperatures below 
273.2 K. (This instrument was the same one damaged by lightning in November 2005 in Darwin. 
It was returned for repair and received a new lens but was calibrated only down to 0 deg 
C, so the problem was neither detected nor repaired.) The IRT was replaced on 2/22/2007.

• Sky Infra-Red Temperature(sky_ir_temp)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Sky Infra Red Temperature Minima(sky_ir_temp_min)

TWP/SMET/C2 - Wind Speed data contain offset due to induced voltage

The marine model of the RM Young wind sensor needs twisted pair shielded cable.  The 
manufacturer did not originally supply the pigtail with twisted pair shielded cable.  Use of 
twisted pair shielded cable for the rest of the cable run to the logger was also not 
specified.  This caused an induced voltage in the wind speed line from the wind direction 
excitation.  The induced voltage varied from sensor to sensor and probably changed anytime 
the cable was replaced or parts of the wind sensor were repaired or replaced. The induced 
voltage has been seen to vary from 0.15 m/s to as much as 1.08 m/s.

• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed minimum(lo_spd_min)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed vector average(up_spd_vec_avg)