SGP/SIRS/E21 - Instrument logger time problem, Unknown

Values of diffuse hemispheric shortwave radiation differ from derived values by at most 70 
Wm^(-2).  The incident appears to be isolated to 3/21, 3/22, and 3/23. An estimation of 
solar noon using downwelling shortwave hemispheric irradiance from the PSP shows solar 
noon to oocur at around 1845GMT on 3/21. Calculated solar noon occurs at E21 at 1831GMT for 
3/21/2004.  There appears to be a time discrepancy in the datalogger for these dates.  
04/01 is the next date with enough sun to determine solar noon and compare to calculated.  
The data from this date appears correct.  Ronald Reed [rreed@ops.sgp.arm.gov] reports 
the logger did not receive any reportable time updates during the late March time period.  
We don't know what happened during these three dates but from 3/24 on data looks acceptable.

Disregard this data.

• Instantaneous uncorrected downwelling shortwave diffuse, shaded pyranometer
  thermopile voltage(inst_diffuse)
• Instantaneous downwelling pyrgeometer thermopile voltage, shaded pyrgeometer(inst_down_long_hemisp_shaded_tp)
• Instantaneous Upwelling Pyrgeometer Dome Thermistor Resistance Pyrgeometer(inst_up_long_dome_resist)
• Instantaneous Upwelling Pyrgeometer Thermopile Pyrgeometer(inst_up_long_hemisp_tp)
• Instantaneous Downwelling Pyrgeometer Case Thermistor Resistance, Shaded
  Pyrgeometer(inst_down_long_shaded_case_resist)
• Instantaneous direct normal shortwave irradiance, pyrheliometer thermopile
  voltage(inst_direct_normal)
• Instantaneous downwelling pyrgeometer dome thermistor resistance, shaded
  pyrgeometer(inst_down_long_shaded_dome_resist)
• Instantaneous Upwelling Pyrgeometer Case Thermistor Resistance, Pyrgeometer(inst_up_long_case_resist)
• Instantaneous Upwelling Shortwave Hemispheric Irradiance, Pyranometer(inst_up_short_hemisp)
• Instantaneous Downwelling Hemispheric Shortwave, Pyranometer Thermopile Voltage(inst_global)
• Time offset from base_time(time_offset)

• (Raw data stream - documentation not supported)

• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Pyranometer, Maxima(up_short_hemisp_max)
• Upwelling Longwave Hemispheric Irradiance, Pyrgeometer, Minima(up_long_hemisp_min)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Upwelling (10 meter) Shortwave Hemispheric Irradiance, Ventilated Pyranometer,
  Standard Deviation(up_short_hemisp_std)
• Time offset from base_time(time_offset)
• Downwelling Shortwave Hemispheric Irradiance, Ventilated Pyrgeometer, Standard
  Deviation(down_short_hemisp_std)
• Downwelling shortwave hemispheric irradiance, pyranometer, maxima(down_short_hemisp_max)
• 10 meter Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)
• Upwelling shortwave hemispheric irradiance, pyranometer, minima(up_short_hemisp_min)
• Instantaneous Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(up_long_netir)
• Instantaneous Downwelling Pyrgeometer Dome Thermistor Temperature, Shaded
  Pyrgeometer(inst_down_long_shaded_dome_temp)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Minima(down_long_hemisp_shaded_min)
• Shortwave Direct Normal Irradiance, Pyrgeometer, Standard Deviation(short_direct_normal_std)
• Downwelling longwave hemispheric irradiance, shaded pyrgeometer(down_long_hemisp_shaded)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Pyrgeometer, Minima(down_short_diffuse_hemisp_min)
• Instantaneous upwelling pyrgeometer case thermistor temperature, pyrgeometer(inst_up_long_case_temp)
• Downwelling shortwave diffuse hemispheric irradiance, pyranometer, maxima(down_short_diffuse_hemisp_max)
• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• 25 meter Upwelling Shortwave Hemispheric Irradiance, Pyranometer(up_short_hemisp)
• Downwelling longwave hemispheric irradiance, shaded pyrgeometer, standard
  deviation(down_long_hemisp_shaded_std)
• Downwelling Longwave Hemispheric Irradiance, Shaded Pyrgeometer, Maxima(down_long_hemisp_shaded_max)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Pyranometer, Standard
  Deviation(down_short_diffuse_hemisp_std)
• Shortwave direct normal irradiance, pyrheliometer, minima(short_direct_normal_min)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• Upwelling longwave hemispheric irradiance, pyrgeometer, maxima(up_long_hemisp_max)
• Downwelling longwave hemispheric net infrared(down_long_netir)
• Instantaneous downwelling pyrgeometer case thermistor temperature, shaded
  pyrgeometer(inst_down_long_shaded_case_temp)
• Downwelling Shortwave Hemispheric Irradiance, Pyranometer, Minima(down_short_hemisp_min)
• Instantaneous Dome Temperature(inst_up_long_dome_temp)