DQRID : D080222.2
Start DateStart TimeEnd DateEnd Time Data Quality Metric
06/01/2003120009/27/20070017Does not affect quality
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Subject:
SGP/RSS/C1 - Stability and nonlinearity corrections
DataStreams:sgprssC1.b1, sgprssC1.00
Description:
From the very beginning after deployment in May 2003 we observed several effects that we 
did not anticipate during the pre-deployment lab test.   They were: (1) Rapid drop in 
responsivity; (2) Responsivity having 1/lambda wavelike periodicity; (3) Appearance of 
nonlinearity within 3 months; (4) Larger than expected diurnal wavelength changes and long term 
wavelength drift. 

Right away we responded with development of correction algorithms and methods.  (1) and 
(2) are corrected to within 2-3% with biweekly lamp calibrations; (3) Nonlinearity factor 
is derived from calibration data and applied in correction; and (4) is efficiently 
corrected with Fourier correlation algorithm applied to every spectrum (once a minute).

Furthermore we perform Langley regression processing  (not a part of official data stream) 
that corrects longer term drifts in responsivity and  should correct calibration lamp 
biases.  The Vo's from Langley regressions are available via RSS  web page.

The overhaul of the instrument is planned to eliminate or at least reduce  nonlinerarity 
stability problems.  We hope that after the overhaul data processing would  be simplified 
and the frequency of calibrations would be reduced.
Suggestions: 
Data users should not be concerned about the effects of the stability and 

nonlinearity in the archived RSS irradiance data.  Data in archives are corrected.  However, users 
who want to investigate data in form of transmittance or optical depth should use Langley 
derived Vo's rather than extraterrestrial irradiance.  Vo's that are available via page have exact 
instrumental spectral resolution and do not have uncertainties associated with other 
extraterrestrial irradiance spectra.
Measurements:sgprssC1.b1:
  • red_shift
  • blue_shift
  • diffuse
  • totalhorizontal
  • sdf_diff
  • directnormal
  • wavelength
  • sdf_th
  • sdf_dn
more
sgprssC1.00:
  • Raw data stream - documentation not supported
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