| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D080222.2 | SGP/RSS/C1 - Stability and nonlinearity corrections | sgprssC1.00, sgprssC1.b1 |
| D130725.2 | SGP/SURFSPECALB/C1 - Data processing problem | sgpsurfspecalb1mlawerC1.c1, sgpsurfspecalb1mlawerC1.s1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 06/01/2003 | 1200 | 09/27/2007 | 0017 |
| Subject: | SGP/RSS/C1 - Stability and nonlinearity corrections |
| DataStreams: | sgprssC1.00, sgprssC1.b1 |
| 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. |
| Measurements: | sgprssC1.00:
sgprssC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2004 | 0000 | 01/26/2013 | 0000 |
| Subject: | SGP/SURFSPECALB/C1 - Data processing problem |
| DataStreams: | sgpsurfspecalb1mlawerC1.c1, sgpsurfspecalb1mlawerC1.s1 |
| Description: | An intermediate process, surfspecalb_transform, of the surfspecalb1mlawer VAP incorrectly treated its input datastream (intermediate datastream surfspecalbmfrsr.c0) as it had a bin alignment equal to the end of the bin, but it was actually the middle of the bin. The result was a shifting of the values with respect to time 10 seconds to the left. The impact on the primary measurement, spectral albedo, was considered to be less than the uncertainty of that measurement. The attached plot sgpsurfspecalb1mlawerC1.20040101.000000.spectral_albedo.png, shows the before and after values of the spectral albedo (in red, the blue line is not visible because the values are almost the same), and the absolute value of the difference of these values (in purple). The axis on the left is for the red line representing albedo, the axis for the difference (purple line) is on the right. The problem occurs for all measurements dimensioned by time. |
| Measurements: | sgpsurfspecalb1mlawerC1.c1:
sgpsurfspecalb1mlawerC1.s1:
|