NSA/SKYRAD/C1 - itermittant IRT bias

A problem with the SKYRAD IRT that itermittantly produced a gradual increase in the sky 
temperature measurement then a sudden correction, as compared to AERI, appears to have been 
caused by a combination of a failing IR detector, a poor signal cable, a contaminated 
(with condensation or frost) mirror or lens, and low ambient temperatures. The positive 
bias was apparently not consistant in either frequency or duration but on days when the 
unusual behavior is observed, it usually occurred from about 00:00 to 06:00 local time. 

The instrument was repaired and recalibrated and the signal cable replaced.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

NSA/SKYRAD/C1 - Datalogger grounding problem

Both PIRs reported unreasonable high readings with coincident low reading from the IRT. 
Since both PIR instruments exhibited exactly the same behaviour and the IRT an opposite 
response during large suspect data excursions this indicates that the false signal maybe the 
result of poor grounding. 

The PIR1,2 data and the IRT data are most adversely affected.  During the problem periods 
PIR irradiance increased (typ pos 200-300W/m2) while the IRT response was negative (typ 
neg 20-30W/m2) but followed the response of the PIR.  The Skyrad shortwave instruments 
were also affected but to much less extent (within their uncertainties).  Data quality flags 
are typically not triggered during these problem periods.

Data logger grounding was improved on 6/10 2005.  The problem hasn't re-occurred since 
that time.

• Raw data stream - documentation not supported

• down_long_hemisp_shaded2_std
• psps_mean
• alt
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• uvb_mean
• nip_min
• down_long_hemisp_shaded1_max
• short_direct_normal_std
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• psp1_min
• psp1_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• nip_max
• sky_ir_temp_std
• base_time
• uvb_min
• down_uvb_std
• external_voltage
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• uvb_sd
• uvb_max
• pirs_sd
• Temperature, Sky Infra-Red(sky_ir_temp)
• psp1_sd
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• nip_sd
• lon
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• internal_voltage
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• down_long_hemisp_shaded_std
• irt1_sd
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• pir1_max
• down_long_hemisp_shaded1_min
• down_long_hemisp_unshaded_std
• sky_ir_temp_min
• sky_ir_temp_max
• psps_min
• down_long_hemisp_shaded2_max
• pirs_mean
• logger_temp
• pirs_min
• pir1_sd
• pirs_max
• psps_sd
• down_short_diffuse_hemisp_std
• pir1_mean
• psp1_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• irt1_mean
• lat
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_short_hemisp_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• irt1_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• bit_data
• time_offset
• irt1_max
• filename
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded2_min
• pir1_min
• psps_max
• down_long_hemisp_shaded1_std

• inst_down_long_unshaded_case_resist
• pir2_uncorr_irradiance
• base_time
• inst_down_uvb_temp
• inst_down_long_shaded2_dome_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_unshaded_tp)
• inst_down_long_shaded2_case_resist
• lat
• pir1_uncorr_irradiance
• pir1_case_therm
• alt
• lon
• inst_down_long_unshaded_dome_resist
• filename
• pir2_dome_therm
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded_tp)
• Irradiance, ultraviolet, downwelling (UV Biometer)(inst_down_uvb_irradiance)
• time_offset
• inst_down_long_shaded_dome_resist
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded_case_resist
• uvb_temp
• inst_down_long_shaded1_dome_resist
• uvb_uncorr_irradiance
• pir2_case_therm
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• pir1_dome_therm

• inst_sky_ir_signal
• inst_down_long_shaded2_case_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_global
• alt
• time_offset
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded1_dome_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded2_dome_resist
• inst_diffuse
• lat
• base_time
• inst_direct_normal
• time
• lon

NSA/GNDRAD/C1/C2 - Upwelling Shortwave data flagged bad are good.

The Upwelling Shortwave at both NSA facilites, C1 and C2, have been flagged red by the 
automatic tests because it is above empiical limits determined for a more southerly site 
(SGP) for this time of year. The data are good and should be flagged green. The test limits 
will be revised for NSA.

• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

NSA/MWR/C1 - Reprocess: Revised Calibration Coefficients

IN THE BEGINNING (June 1992), the retrieval coefficients used to derive 
the precipitable water vapor (PWV) and liquid water path (LWP) from the 
MWR brightness temperatures were based on the Liebe and Layton (1987) 
water vapor and oxygen absorption model and the Grant (1957) liquid 
water absorption model.

Following the SHEBA experience, revised retrievals based on the more 
recent Rosenkranz (1998) water vapor and oxygen absorption models and 
the Liebe (1991) liquid waer absorption model were developed.  The 
Rosenkranz water vapor absorption model resulted a 2 percent increase 
in PWV relative to the earlier Liebe and Layton model.  The Liebe 
liquid water absorption model decreased the LWP by 10% relative to the 
Grant model.  However, the increased oxygen absorption caused a 
0.02-0.03 mm (20-30 g/m2) reduction in LWP, which was particularly 
significant for low LWP conditions (i.e. thin clouds encountered at 
SHEBA).

Recently, it has been shown (Liljegren, Boukabara, Cady-Pereira, and 
Clough, TGARS v. 43, pp 1102-1108, 2005) that the half-width of the 
22 GHz water vapor line from the HITRAN compilation, which is 5 percent 
smaller than the Liebe and Dillon (1969) half-width used in Rosenkranz 
(1998), provided a better fit to the microwave brightness temperature 
measurements at 5 frequencies in the range 22-30 GHz, and yielded more 
accurate retrievals. Accordingly, revised MWR retrieval coefficients 
have been developed using MONORTM, which utilizes the HITRAN compilation 
for its spectroscopic parameters.  These new retrievals provide 3 
percent less PWV and 2.6 percent greater LWP than the previous 
retrievals based on Rosenkranz (1998).

Although the MWR data will be reprocessed to apply the new monortm-based 
retrievals, for most purposes it will be sufficient to correct the data 
using the following factors:

PWV_MONORTM = 0.9695 * PWV_ROSENKRANZ
LWP_MONORTM = 1.026  * LWP_ROSENKRANZ

The Rosenkranz-based retrieval coefficients became active at NSA.C1 
20020425.1900.  The MONORTM-based retrieval coefficients became active 
at NSA.C1 20050629.0000.

Note: a reprocessing effort is already underway to apply the 
Rosenkranz-based retrieval coefficients to all MWR prior to April 
2002.  An additional reprocessing task will be undertaken to apply 
the MONORTM retrieval to all MWR data when the first is completed. 
Read reprocessing comments in the netcdf file header carefully to 
ensure you are aware which retrieval is in play.

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• mean_liq_mwr
• mean_vap_mwr

• vaptip
• liqtip

NSA/GNDRAD/C1 - Power Disconnected Briefly

Power to the Tip tower and Groundrad was disconnected briefly while ground resistance 
measurements were made. 

The following comments are from Inst. Mentor Tom Stoffel: 

The longwave and shortwave irradiances from GNDRAD were not effected by the
temporary power disconnect.  Data are good.  This would have only stopped
the ventilators for a brief time and the data do not show any signs of poor
instrument responses.

The "sfc_ir_temp" data were, however, impacted during the brief (2
readings?) interval.

• Effective Surface (Skin) Temperature(sfc_ir_temp)
• external_voltage

NSA/SKYRAD/C1 - IRT failure

The IRT failed and was replaced with a spare.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

NSA/SKYRAD/C1 - Instrument logger, possible gounding problem

Possible Skyrad datalogger grounding issues have re-appeared at NSA/C1 for only this short 
time period.  Anomalous data readings during the time range specified are similar to 
problem which occurred in early summer 2005.

• Raw data stream - documentation not supported

• down_long_hemisp_shaded2_std
• down_long_hemisp_unshaded_std
• sky_ir_temp_min
• sky_ir_temp_max
• psps_mean
• psps_min
• down_long_hemisp_shaded2_max
• pirs_mean
• alt
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• logger_temp
• nip_min
• uvb_mean
• down_long_hemisp_shaded1_max
• pir1_sd
• pirs_min
• short_direct_normal_std
• pirs_max
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• psps_sd
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• psp1_min
• psp1_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• pir1_mean
• nip_max
• psp1_mean
• sky_ir_temp_std
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• base_time
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• irt1_mean
• uvb_min
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• lat
• down_uvb_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• external_voltage
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• uvb_sd
• down_short_hemisp_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• uvb_max
• pirs_sd
• irt1_min
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• bit_data
• Temperature, Sky Infra-Red(sky_ir_temp)
• time_offset
• psp1_sd
• irt1_max
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• filename
• down_long_hemisp_shaded2_min
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• lon
• nip_sd
• pir1_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• internal_voltage
• down_long_hemisp_shaded_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• irt1_sd
• psps_max
• pir1_max
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded1_min

• inst_down_long_shaded1_case_resist
• inst_down_long_shaded1_dome_resist
• inst_sky_ir_signal
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded2_case_resist
• inst_diffuse
• lat
• base_time
• inst_direct_normal
• time
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_global
• lon
• alt
• time_offset

NSA/SKYRAD/C1 - Reprocess: Incorrect datalogger program affecting PIR1 and PIR2 
downwelling longwave

The excitation delays using in measuring the PIR1 case thermistor commonly named "Case1" 
and the PIR2 dome thermistor called "Dome2" were discovered to have been incorrectly set 
to 0 in the Skyrad datalogger program when the new CR23X based Skyrad loggers were 
installed.  The result of no delay in these measurements results in an error in the measured 
resistance of the thermistors, Case1 and Dome2 and thus the calculated PIR1 and PIR2 
irradiances.  The errors are inversely proportial to temperature.

Users can apply the temperature dependent irradiance corrections shown in the table below. 
 Recall that the reported uncertainty of PIRs is typically +-.25% to +-.5% or 1 to 2 
W/m2.  The error corrections become the same order of magnitude or larger than the 
instrument uncertainties at or below 260K or 9F. 

Correction Table for Skyrad (TWP and NSA) DIR1 and DIR2 Irradiance				
	DIR1	DIR1	DIR2	DIR2
T[F]	Tcase[K]	Correction[W/m2]	Tdome[K]	Correction[W/m2]
109.4	316.13	0.00	316.13	0.00
100.5	311.20	-0.15	311.20	0.12
93.2	307.14	-0.12	307.14	0.10
87.0	303.70	-0.10	303.70	0.08
81.6	300.70	-0.17	300.70	0.14
77.0	298.15	-0.22	298.15	0.18
59.4	288.35	-0.34	288.35	0.27
47.4	281.72	-0.23	281.72	0.18
38.5	276.74	-0.42	276.74	0.34
31.3	272.77	-0.48	272.77	0.38
25.4	269.48	-0.61	269.48	0.49
20.3	266.67	-0.67	266.67	0.54
16.0	264.25	-0.82	264.25	0.66
12.1	262.11	-0.98	262.11	0.79
8.7	260.19	-0.97	260.19	0.78
5.6	258.46	-1.07	258.46	0.86
2.7	256.89	-1.17	256.89	0.94
0.1	255.44	-1.33	255.44	1.07
-2.3	254.11	-1.41	254.11	1.13
-4.5	252.87	-1.43	252.87	1.15
-6.6	251.71	-1.52	251.71	1.22
-8.5	250.63	-1.63	250.63	1.31
-10.4	249.62	-1.73	249.62	1.39
-12.2	248.58	-1.79	248.58	1.44
-15.4	246.82	-1.93	246.82	1.55
-18.3	245.23	-2.05	245.23	1.65
-20.9	243.78	-2.22	243.78	1.78
-23.3	242.44	-2.36	242.44	1.89
-25.5	241.21	-2.58	241.21	2.07
-27.5	240.07	-2.65	240.07	2.13
-29.5	239.01	-2.75	239.01	2.21
-31.3	238.00	-3.02	238.00	2.42

• down_long_hemisp_shaded2_std
• down_long_hemisp_shaded2_min
• down_long_hemisp_shaded2_max
• down_long_hemisp_shaded1_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• down_long_hemisp_shaded1_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• down_long_hemisp_shaded1_min

• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded1_case_resist
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded2_case_resist
• inst_down_long_shaded1_dome_resist

NSA/GNDRAD/C1 - power outage affecting some GNDRAD sensors

During the power outage the upwelling global measurement from the PSP instrument shows a 
slight increase from -5 to +0 W/m2.  This is due to removal of thermal offsets induced by 
the AC heater during the power outage.  This heater is installed within the PSP 
ventilator - it is necessary for the NSA/C1 climate.
The upwelling longwave PIR instrument is unaffected due to case and dome temperature 
corrections.
The IRT is AC powered and was not operational during this time period.

• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• up_short_hemisp_std
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• Surface Infra-Red Temperature Minima(sfc_ir_temp_min)
• sfc_ir_temp_std
• Surface Infra-Red Temperature Maxima(sfc_ir_temp_max)
• Effective Surface (Skin) Temperature(sfc_ir_temp)
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

• Raw data stream - documentation not supported

• inst_sfc_ir_signal

NSA/SKYRAD/C1 - Power outage affecting some SKYRAD instruments

During the power outage the downwelling global measurement from the PSP instrument and 
downwelling diffuse 8-48 instrument shows a slight increase from -5 to +0 W/m2.  This is due 
to removal of thermal offsets induced by the AC heater during the power outage.  This 
heater is installed within the PSP ventilator - it is necessary for the NSA/C1 climate.
The downwelling longwave PIR instrument is unaffected due to case and dome temperature 
corrections.
The IRT is AC powered and was not operational during this time period.

• Raw data stream - documentation not supported

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_short_hemisp_std
• Temperature, Sky Infra-Red(sky_ir_temp)

• inst_global
• inst_diffuse
• inst_sky_ir_signal

NSA/SKYRAD/C1 - Instrument noise

Skyrad data appears affected by noise creating bias in analog voltage readings on 
02/15/2006 from 1300-1800GMT and again on 02/16/2006 from 1300-1500GMT.  The second night the 
noise is attenuated significantly.  By 02/17 no bias/noise is detectable. The thermistor 
measurements in PIR1 and PIR2 were unaffected during these excursions and showed no 
deviation from normal during the problem period.  In addition, the onboard logger temperature and 
battery voltage read normal throughout.  The problem has not reappeared as of 4/25/2006.

• down_long_hemisp_shaded2_std
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• sky_ir_temp_min
• sky_ir_temp_max
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• down_long_hemisp_shaded2_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• down_long_hemisp_shaded1_max
• down_short_hemisp_std
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• short_direct_normal_std
• Temperature, Sky Infra-Red(sky_ir_temp)
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• down_long_hemisp_shaded2_min
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• sky_ir_temp_std
• down_long_hemisp_shaded1_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• down_long_hemisp_shaded1_min

• inst_down_long_shaded1_case_resist
• inst_down_long_shaded1_dome_resist
• inst_sky_ir_signal
• inst_direct_normal
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_global
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded2_case_resist
• inst_diffuse

NSA/SKYRAD/C1 - 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.

• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)

NSA/GNDRAD/C1 - 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.

• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)

NSA/SKYRAD/C1 - Summer solstice shading of radiometers

On and around the summer solstice, the NIP (Direct Normal shortwave measurement) and PSP 
(global hemispheic shortwave measurement) radiometers are shaded by other instruments or 
support structures.  Shading azimuths have been determined for this site.  The radiometer 
mentor suggests not using the data from the NIP and PSP radiometers when the sun is 
within the following azimuth bounds (typically from May 8th to August 5th of each year):
Instrmt Obstruction     AzStart     AzEnd     
NIP     rad table       346         358
NIP     met tower       13          15
PSP     mfrsr           6           16

• psps_sd
• psp1_sd
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• psps_mean
• psps_min
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• nip_sd
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• psp1_min
• psp1_max
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• nip_min
• psps_max
• nip_max
• psp1_mean
• down_short_hemisp_std
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)

NSA/GNDRAD/C1 - Incorrect calibration coefficients

BarrowC1, Gndrad. On Aug 11th the PSP-US was changed out and the Campbell program was 
changed to reflect this.  However, an old program that uses the 4 coefficient PIR cal factors 
was used. The PIR-UIR was not changed out, however, the logger program coeffs reverted 
back to the 4 Coeffcients.  The Eppley PIR-UIR coefficients for this S/N 30168F3 are :  
K0=0.0, K1(aka k)=.25253, K2= 1.0, K3=-4, Kr=0.0.

• net_min
• pir1_mean
• net_std
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)
• pir1_sd
• net_mean
• net_sd
• up_long_hemisp_std
• net_max
• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• pir1_max
• pir1_min

• Raw data stream - documentation not supported

• pir1_case_therm
• inst_up_long_hemisp_tp
• inst_up_long_case_resist
• pir1_dome_therm
• pir1_voltage
• inst_up_long_dome_resist

• inst_up_long_dome_resist
• inst_up_long_hemisp_tp
• inst_up_long_case_resist

NSA/SKYRAD/C1 - Preventive maintenance

Preventive maintenance to rebuild ventilator fan and exchange instruments during this time 
removed Skyrad instruments from operation.  Most data collected are not scientifically 
relevant.

• down_long_hemisp_shaded2_std
• down_long_hemisp_unshaded_std
• psps_mean
• psps_min
• down_long_hemisp_shaded2_max
• pirs_mean
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)
• uvb_mean
• nip_min
• down_long_hemisp_shaded1_max
• pirs_min
• pir1_sd
• short_direct_normal_std
• pirs_max
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• psps_sd
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Minima(down_long_hemisp_unshaded_min)
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer, Maxima(down_long_hemisp_unshaded_max)
• psp1_min
• psp1_max
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• pir1_mean
• psp1_mean
• nip_max
• Downwelling Ultra-Violet Irradiance, UV Biometer(down_uvb)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• uvb_min
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• down_uvb_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• external_voltage
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• nip_mean
• Downwelling Ultra-Violet Irradiance, UV Biometer, Maxima(down_uvb_max)
• uvb_sd
• down_short_hemisp_std
• uvb_max
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer1(down_long_hemisp_shaded1)
• pirs_sd
• Irradiance, longwave, downwelling, hemispheric, shaded pyrgeometer2(down_long_hemisp_shaded2)
• psp1_sd
• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• filename
• Downwelling Longwave Hemispheric Irrad., Shaded Ventilated Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• down_long_hemisp_shaded2_min
• Downwelling Longwave Hemispheric Irradiance, Unshaded Pyrgeometer(down_long_hemisp_unshaded)
• nip_sd
• pir1_min
• Downwelling Ultra-Violet Irradiance, UV Biometer, Minima(down_uvb_min)
• Downwelling Longwave Hemispheric Irradiance, Shaded Ventilated Pyrgeometer(down_long_hemisp_shaded)
• down_long_hemisp_shaded_std
• psps_max
• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• pir1_max
• down_long_hemisp_shaded1_std
• down_long_hemisp_shaded1_min

• inst_down_long_shaded1_case_resist
• inst_down_long_shaded1_dome_resist
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer2)(inst_down_long_hemisp_shaded2_tp)
• inst_down_long_shaded2_dome_resist
• inst_down_long_shaded2_case_resist
• inst_diffuse
• inst_direct_normal
• Irradiance, longwave, downwelling, hemispheric, thermopile (Shaded Pyrgeometer1)(inst_down_long_hemisp_shaded1_tp)
• inst_global

NSA/GNDRAD/C1 - Preventive maintenance

Preventive maintenance including ventilator repairs and instrument changeout during this 
time resulted in data that are not scientifically relevant.

• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• psp1_sd
• net_std
• net_mean
• net_max
• up_long_hemisp_std
• psp1_mean
• pir1_max
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• up_short_hemisp_std
• net_min
• pir1_mean
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• pir1_sd
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)
• net_sd
• psp1_min
• psp1_max
• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)
• pir1_min

• inst_up_long_dome_resist
• inst_up_short_hemisp
• inst_up_long_hemisp_tp
• inst_up_long_case_resist

NSA/SKYRAD/C1 - Reprocessed: Incorrect calibration coefficient

Installed Skyrad PSP (downwelling shortwave hemispheric irradiance) had calibration 
coefficient Rs applied when it should have used Rsc.  ARM is using IR corrected Rsc and CFc 
coefficients for PSPs deployed at all facilities.  

PSP #32026 should use RSc@45=8.7578 ?V/W/m? and not Rs@45=8.6335.

Reprocessed to correct downwelling shortwave hemispheric irradiance (DS) by:
DS(new) = (DS(old) / 115.83 ) * 114.18

Reprocessing completed March 2008.

• Radiation, shortwave, downwelling total hemispheric irradiance, 1-min avg(down_short_hemisp)
• down_short_hemisp_std
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Maxima(down_short_hemisp_max)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyranometer, Minima(down_short_hemisp_min)

• inst_global

NSA/GNDRAD/C1 - Reprocessed: Incorrect calibration coefficient

Installed Gndrad PSP (upwelling shortwave hemispheric irradiance) had calibration 
coefficient RS applied when it should have used Rsc.  ARM is using IR corrected coefficients 
Rsc@45 and CFc@45 for PSPs deployed at all facilities.  

PSP #32012F3 should use RSc@45=109.39 and not Rs@45=110.97.  

Reprocessed to correct upwelling shortwave hemispheric irradiance (US) by:
US(new) = (US(old) / 110.97 ) * 109.39

Reprocessing completed March 2008.

• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Maxima(up_short_hemisp_max)
• up_short_hemisp_std
• Upwelling Shortwave Hemispheric Irradiance, Unventilated Pyranometer, Minima(up_short_hemisp_min)
• Radiation, shortwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_short_hemisp)

• inst_up_short_hemisp

NSA/SKYRAD/C1 - Instrument cleaning effects

Starting Dec 16th the Skyrad PIR1 and PIR2 (down_long_hemispheric)started differing by 
greater than 30W/m2 at times.  This is much greater than expected  for these instruments 
(typical is <10-15 W/m2).  NSA OMIS reports and observer comments reveal that PM 
periodically clean the snow from the IRT and ventilator fans on Skyrad and Gndrad.  In the case of 
the Skyrad PIRs, one lies in the wind shadow of the other and builds up more snow which is 
periodically cleaned out and then builds up again causing the PIR1 PIR2 discrepancies.

Disregard down_long_hemispheric during this time period. However, data suggests PIR2 is 
most likely at fault - potentially use PIR1 data during this time period.

• inst_down_long_hemisp2_tp
• inst_down_long_hemisp2_case_temp
• inst_down_long_hemisp1_dome_temp
• down_long_hemisp2_min
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• down_long_hemisp2_max
• down_long_hemisp2_std
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer2(down_long_hemisp2)
• inst_down_long_hemisp1_case_temp
• down_long_hemisp1_min
• inst_down_long_hemisp1_tp
• down_long_hemisp1_std
• inst_down_long_hemisp2_dome_temp
• down_long_hemisp1_max

• inst_down_long_hemisp1_dome_resist
• inst_down_long_hemisp2_tp
• inst_down_long_hemisp2_case_resist
• inst_down_long_hemisp2_dome_resist
• inst_down_long_hemisp1_tp
• inst_down_long_hemisp1_case_resist

NSA/SKYRAD/C1 - IRT mirror heater failure

The heater of the IRT gold mirror failed due to a broken wire (that probably occurred on 
12/13 during maintenance of the solar tracker) allowing snow and frost to accumulate on 
the mirror until it was cleared during daily preventative maintenance. The problem was 
corrected when the heater wires were replaced.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

• inst_sky_ir_signal

NSA/SKYRAD/C1 - Direct and Diffuse incorrect

The short_direct_normal (NIP) instrument and cable were damaged by tracker rewind 
malfunction. Tracker and NIP replaced on 4/22 2200GMT but tracker not operational until 4/23 
1815GMT.  Thus, down_short_diffuse_hemisp (8-48) was not shaded 4/22 to 4/23.

Do not use 8-48 data from 4/22 to 4/23. NIP data is not recoverable during entire time but 
can be estimated using component sum for each 1 minute data: Direct = (global - 
diffuse)/cos(zenith angle)

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• short_direct_normal_std
• down_short_diffuse_hemisp_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)

• inst_diffuse
• inst_direct_normal

NSA/SKYRAD/C1 - Tracker inoperative

Tracker stopped working at this site during the time range specified. Reason for failure 
is unknown.  Tracker power cycled and restarted by maintenance 06/30 2008 1740 GMT.

The short_direct_normal (NIP) and down_short_diffuse_hemisp (8-48) data are bad during 
this time.  Data are not recoverable.

• Radiation, shortwave, downwelling diffuse hemispheric irradiance, 1-min avg(down_short_diffuse_hemisp)
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Maxima(down_short_diffuse_hemisp_max)
• down_short_diffuse_hemisp_std
• Downwelling Shortwave Diffuse Hemisp. Irrad., Ventilated Pyranometer, Minima(down_short_diffuse_hemisp_min)

• inst_diffuse
• inst_direct_normal

NSA/GNDRAD/C1 - Upwelling PIR ventilator fan failure

The PIR exhibited a positive bias of approximately 6 W/m2 compared to the upwelling IRT 
due to ventilator fan failure.  Thus, the up_long_hemisp, data stream is high by about 6 
W/m2.    
   
Bias is not consistent and depends on atmospheric conditions. Either disregard the 
up_long_hemisp data or use the IRT for an estimate of the up_long_hemisp values during this time 
period.

• inst_up_long_hemisp_dome_temp
• inst_up_long_hemisp_tp
• inst_up_long_hemisp_case_temp
• up_long_hemisp_std
• Radiation, longwave, at 10-m height, upwelling hemispheric irrad., 1-min avg(up_long_hemisp)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Maxima(up_long_hemisp_max)
• Upwelling Longwave Hemispheric Irradiance, Unventilated Pyrgeometer, Minima(up_long_hemisp_min)

• inst_up_long_hemisp_case_resist
• inst_up_long_hemisp_tp
• inst_up_long_hemisp_dome_resist

NSA/SKYRAD/C1 - IRT covered with snow

The IRT mirror was buried with snow by the dew-line snow-blower.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

NSA/SKYRAD/C1 - Frosting/Condensation

The down_long_hemisp1 varied up to 40 W/m^2 higher than down_long_hemisp2 during the 
affected time periods. Cold temperatures reported by the IRT suggest the issue is with PIR1.  
Icing or frost on PIR1 or within the ventilator may be to blame but ops reports can't 
substantiate this. Data from PIR1 should be avoided during these suspect time periods.

• down_long_hemisp1_min
• down_long_hemisp1_std
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer1(down_long_hemisp1)
• down_long_hemisp1_max

• inst_down_long_hemisp1_tp
• inst_down_long_hemisp1_case_resist
• inst_down_long_hemisp1_dome_resist