NSA/AERI/C1 - Excessive Noise in C1 AERI data

Initially it was believed that the greater noise level in AERI C1 data was due to the 
extended range detector, which has lower sensitivity. However, when the S01 AERI was 
installed next to the C1 AERI and it stabilized on 9/30/2005, it was observed that the noise 
levels on the newly installed S01 AERI were much lower than for the C1 AERI. Therefore, the 
excessive noise of the C1 AERI is not due to the fundamental nature of the extended range 
detector but instead due to failure within the detector. 

The failure could be due to a poor D* value of too high a detector temperature. It could 
also be caused by optical alignment issues. In either case, the spectral radiance data 
have much more noise and that results in larger error bars when using the radiance data, 
especially long wave data as monitored by the LW_HBB_NEN flag.

On 9/30/2005, the S01 AERI, which is next to the C1 AERI, came on-line and is producing 
low noise data. The S01 data should be used instead of the C1 data where low noise 
requirements are needed.

On 6/26/2006, the S01 AERI went offline due to a laser failure.  The C1 AERI was moved to 
the connex where data were within reasonable limits for an extended range detector.  
Beginning 20060701, the C1 data are the preferred AERI data set at the NSA Barrow location.

• Shortwave window radiance average (2510_2515 cm^-1)(shortwaveWindowRadiance2510_2515)
• Longwave elevated air brightness temperature from radiance average (700_705
  cm^-1)(elevatedLayerAirTemp700_705)
• Shortwave window brightness temperature from radiance average (2510_2515 cm^-1)(shortwaveWindowAirTemp2510_2515)
• Characteristic value representing overall shortwave channel responsivity(SWresponsivity)
• Shortwave surface air brightness temperature from radiance average (2295_2300
  cm^-1)(surfaceLayerAirTemp2295_2300)
• AERI LW Scene Variability Spectral Averages (Ch1)(SkyUniformityCh1)
• Shortwave elevated air brightness temperature from radiance average (2282_2287
  cm^-1)(elevatedLayerAirTemp2282_2287)
• Longwave radiance average (675-680 cm^-1) Surface Air(surfaceLayerRadiance675_680)
• Shortwave radiance average (2282_2287 cm^-1) Elevated Air(elevatedLayerRadiance2282_2287)
• The noise equivalent radiance observed in the longwave channel during a sky view
  at 1000 cm^-1(LWskyNEN)
• Logical flag indicating whether longwave channel noise equivalent radiance is
  acceptable in sky view (true/false). Determined using LWskyNEN and
  LWskyNENlimit.(LWskyNENacceptable)
• Longwave surface air brightness temperature from radiance average (675_680
  cm^-1)(surfaceLayerAirTemp675_680)
• The noise equivalent radiance observed in the shortwave channel during a sky
  view at 2500 cm^-1(SWskyNEN)
• Radiance standard deviation during sky view averaged over (985_990 cm^-1)(skyViewStdDevRadiance985_990)
• Radiance standard deviation during sky view averaged over (2295_2300 cm^-1)(skyViewStdDevRadiance2295_2300)
• AERI SW Scene NESR Spectral Averages (Ch2)(SkyNENCh2)
• Characteristic value representing overall longwave channel responsivity(LWresponsivity)
• AERI LW Scene NESR Spectral Averages (Ch1)(SkyNENCh1)
• Radiance standard deviation during sky view averaged over (2510_2515 cm^-1)(skyViewStdDevRadiance2510_2515)
• AERI LW Responsivity Spectral Averages (Ch1)(ResponsivitySpectralAveragesCh1)
• Radiance standard deviation during sky view averaged over (2282_2287 cm^-1)(skyViewStdDevRadiance2282_2287)
• Noise-equivalent Radiance in Hot Blackbody at 1000 cm-1(LW_HBB_NEN)
• AERI SW Responsivity Spectral Averages (Ch2)(ResponsivitySpectralAveragesCh2)
• AERI LW Scene Brightness Temp Spectral Averages (Ch1)(SkyBrightnessTempSpectralAveragesCh1)
• Longwave window radiance average (985_990 cm^-1)(longwaveWindowRadiance985_990)
• Longwave radiance average (700_705 cm^-1) Elevated Air(elevatedLayerRadiance700_705)
• Radiance standard deviation during sky view averaged over (700_705 cm^-1)(skyViewStdDevRadiance700_705)
• Logical flag indicating whether shortwave channel noise equivalent radiance is
  acceptable in sky view (true/false). Determined using SWskyNEN and
  SWskyNENlimit.(SWskyNENacceptable)
• AERI LW HBB 2min NESR Estimate #2 derived from sequential HBB views (Ch1)(HBB2minNENestimateNo2Ch1)
• AERI SW HBB 2min NESR Estimate #1 derived from variance during HBB view (Ch2)(HBB2minNENestimateNo1Ch2)
• Noise-equivalent Radiance in Hot Blackbody at 2500 cm-1(SW_HBB_NEN)
• Shortwave radiance average (2295_2300 cm^-1) Surface Air(surfaceLayerRadiance2295_2300)
• AERI SW Scene Variability Spectral Averages (Ch2)(SkyUniformityCh2)
• AERI LW HBB 2min NESR Estimate #1 derived from variance during HBB view (Ch1)(HBB2minNENestimateNo1Ch1)
• AERI SW HBB 2min NESR Estimate #2 derived from sequential HBB views (Ch2)(HBB2minNENestimateNo2Ch2)
• AERI SW Scene Brightness Temp Spectral Averages (Ch2)(SkyBrightnessTempSpectralAveragesCh2)
• AERI SW Scene Radiance Spectral Averages (Ch2)(SkyRadianceSpectralAveragesCh2)
• Radiance standard deviation during sky view averaged over (675_680 cm^-1)(skyViewStdDevRadiance675_680)
• Longwave window brightness temperature from radiance average (985_990 cm^-1)(longwaveWindowAirTemp985_990)
• AERI LW Scene Radiance Spectral Averages (Ch1)(SkyRadianceSpectralAveragesCh1)

• Downwelling radiance interpolated to standard wavenumber scale(mean_rad)