Start Date | Start Time | End Date | End Time | Data Quality Metric |
---|---|---|---|---|
06/01/2003 | 1200 | 09/27/2007 | 0017 | Does not affect quality |
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: more
sgprssC1.00: more |