SGP/SIRS/E12 - Incorrect Times

The ntpd server (time adjustment) stopped working on Feb. 19th at 22:12:16 GMT, and the 
clock was corrected by -5600.177269 seconds
on March 10th at 22:47 GMT. The recorded times for observations are
off by amounts ranging from 0 seconds on Feb. 19th to 5600 seconds
on March 10th.

• sswfluxdn_measured
• Measured Downwelling Diffuse Shortwave Irradiance (dif)(difswfluxdn_measured)
• coef_date
• coef_clearsky_albedo_a
• coef_clearsky_albedo_b
• sun_earth_distance_dailyaverage
• Measured Downwelling Direct Shortwave Irradiance (dir)(dirfluxdn_measured)
• difratiodn_clearskyfit
• Clear-sky Fit Estimated Downwelling Direct Shortwave Irradiance (cdir)(dirfluxdn_clearskyfit)
• flag_clearsky_detection
• Irradiance, shortwave, downwelling, global,measured(gswfluxdn_measured)
• time_offset_LST
• coef_clearsky_guvb_a
• coef_clearsky_guvb_b
• base_time_LST
• site
• coef_clearsky_gsw_b
• sswfluxdn_clearskyfit
• Clear-sky Fit Estimated Downwelling Diffuse Field Shortwave Irradiance (cdif)(difswfluxdn_clearskyfit)
• gswfluxdn_cloudeffect
• guvbdn_measured
• solar_cos_z
• coef_clearsky_gsw_a
• coef_clearsky_dsw_c
• coef_clearsky_dsw_a
• coef_clearsky_dsw_b
• difswfluxdn_cloudeffect
• difratiodn_measured
• Clear-sky Fit Estimated Downwelling Global Shortwave Irradiance (cgsw)(gswfluxdn_clearskyfit)
• Measured Surface Albedo from Shortwave Irradiance Measurements (alb)(albedosw_measured)
• coef_clearsky_ssw_a
• coef_clearsky_difratio_b
• coef_clearsky_difratio_a
• sun_earth_distance
• time_offset
• guvbdn_clearskyfit
• sswfluxdn_cloudeffect
• coef_clearsky_ssw_b
• base_time
• Clear-sky Fit Estimated Surface Albedo from Shortwave Irradiance Measurements
  (calb)(albedosw_clearskyfit)

SGP/SIRS/E12 - SWFANAL Data description error

The long name attribute for the cloud effect fields incorrectly
defines the cloud effect to be the difference between the 
clearskyfit and measured values:
   
"Difference: ***fluxdn_clearskyfit - ***fluxdn_measured (***fcg)" ;
   
The cloud effects are correctly calculated by subtracting the
irradiance calculated in the clear sky fit from the measured 
irradiance.
   
"Difference: ***fluxdn_measured - ***fluxdn_clearskyfit (***fcg)" ;
   
NOTE: this is just a documentation error.  The data are correctly
calculated.

• gswfluxdn_cloudeffect
• sswfluxdn_cloudeffect
• difswfluxdn_cloudeffect

SGP/QCRAD/C1 - Reprocess: SW data require -1 multipler

Magnitude of data are correct, however, 2 wires were crossed producing negative values for 
SW Global Down, SW Global Up, SW Direct Normal, and SW Diffuse Down. Problem has been 
fixed at site.

Users of this data should multiply by -1 to get the correct values for SW Global Down, SW 
Global Up, SW Direct Normal, and SW Diffuse Down. Data will be reprocessed.

Documented in instrument DQR D000919.1.

• Best Estimate Global Downwelling Shortwave Hemispheric Irradiance(BestEstimate_down_short_hemisp)
• Irradiance, shortwave, downwelling, diffuse, hemispheric, pyranometer(down_short_diffuse_hemisp)
• Shortwave Direct Normal Irradiance(short_direct_normal)
• Upwelling shortwave hemispheric irradiance, pyranometer(up_short_hemisp)

SGP/QCRAD/C1 - Upwelling SW cable problem

Starting 11/13/2006, the C1 SIRS Upwelling Shortwave (up_short_hemisp) started to show 
large differences in comparison to co-located E13 SIRS and C1 IRT25m.  After much 
troubleshooting and gnashing of teeth it was discovered that rodents had chewed through the 
instrument cables at the bottom of the tilt tower. Cables were replaced 01/23/2007 1930GMT.

Documented in instrument DQR D061121.2

• Upwelling shortwave hemispheric irradiance, pyranometer(up_short_hemisp)

SGP/QCRAD/C1 - Sensor cable problem

Beginning October 3, 2007, the upwelling longwave irradiance (up_long_hemisp, aka "UIR") 
started to spike to unreasonable values positively offset from the co-located E13 by over 
100W/m2.  On January 17 2008 the UIR values become consistently bad due to bad UIR dome 
thermistor wiring.  Problem appears as a resistive offset in the dome thermistor but due 
to nature of failure (unknown cable problem) data correction would not yield any better 
data than the co-located E13 UIR instrument that is known to be operating correctly. 
Instrument cable replacement on 4/22 fixed the problem.

Thermopile data (netIR) from this instrument is good.  However, incoming irradiance data 
is not correctable due to bad UIR dome thermistor wiring within the instrument cable. 

Documented in instrument DQR D071022.4.

• Upwelling longwave hemispheric irradiance, pyrgeometer(up_long_hemisp)

SGP/QCRAD/C1 - SW direct normal data drop out

NIP cable had failed during this time period.  Short_direct_normal data are not 
recoverable during this time period. However, it can be reconstructed using the following formula 
for each one minute data:
   short_direct_normal = (down_short_hemisp-down_short_diffuse_hemisp)/cos(zenith angle)

Documented in instrument DQR D090623.1

• Shortwave Direct Normal Irradiance(short_direct_normal)

SGP/QCRAD/C1 - Failed upwelling SW cable

The upwelling shortwave hemispheric (up_short_hemisp) data were missing or incorrect due 
to a bad cable.  Cable was replaced on 6/30 and the problem was resolved.

Documented in instrument DQR D100701.1

• Upwelling shortwave hemispheric irradiance, pyranometer(up_short_hemisp)

SGP/QCRAD/C1 - NIP failure

The short_direct_normal (NIP instrument) cable failed during this time period.	Data are 
not recoverable.

Users can derive an estimate of direct normal values using the following formula:
short_direct_normal = (down_short_hemisp - down_short_diffuse_hemisp)/cos(zenith angle)

Documented in instrument DQR D110628.2

• Shortwave Direct Normal Irradiance(short_direct_normal)

SGP/QCRAD/C1 - Case and dome temperatures not available

Longwave downwelling and upwelling case and dome temperatures are not available during 
this time period because they were not kept in the sirs.a1 files and sirs.b1 files are not 
available. This means that some longwave tests and corrections can't be applied.

• LWupTd
• LWupTc
• LWdnTd
• LWdnTc
• Upwelling longwave hemispheric irradiance, pyrgeometer(up_long_hemisp)
• Downwelling longwave hemispheric irradiance, pyrgeometer(down_long_hemisp)