DQR ID | Subject | Data Streams Affected |
---|---|---|
D071012.1 | SGP/SWS/C1 - Spectrometer heater controller failed | sgpswsC1.b1 |
D071116.1 | SGP/SWS/C1 - Instrument offline for annual calibration | sgpswsC1.b1, sgpswsauxC1.b1 |
D090716.1 | SGP/SWS/C1 - Temperature instability of InGaAs detector | sgpswsC1.b1, sgpswsauxC1.b1 |
D090716.2 | SGP/SWS/C1 - Contamination by scattered light on optics. | sgpswsC1.b1 |
Start Date | Start Time | End Date | End Time |
---|---|---|---|
09/25/2007 | 1100 | 10/05/2007 | 1430 |
Subject: | SGP/SWS/C1 - Spectrometer heater controller failed |
DataStreams: | sgpswsC1.b1 |
Description: | A heater controller failed on the Shortwave Spectrometer instrument (SWS). The heater maintained the Silicon diode array spectrometer temperature at 27 +/-0.2 Celsius. Operatation of the instrument is not dependent on the proper operation of the heater, therefore the SWS was run during the 10 day period in which the problem was diagnosed and repaired. However, up to a 4 percent error in radiance values can be expected in the wavelength range from 900 nm to 981 nm. The SWS data spans a wavelength range of 350 nm to 2150 nm with a typical error in radiance value of 2 percent. From our analysis, the data with errors outside of the typical, only spans a small portion of the total wavelength range. An instrument calibration with the heater malfunctioning was performed on September 26, 2007, and a response function was generated by the SWS mentor. If necessary, data users can contact the mentor to obtain the response function which will improve but not eliminate completely the errors in absolute spectral radiance values measured. |
Measurements: | sgpswsC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
11/16/2007 | 1600 | 01/02/2008 | 1910 |
Subject: | SGP/SWS/C1 - Instrument offline for annual calibration |
DataStreams: | sgpswsC1.b1, sgpswsauxC1.b1 |
Description: | SWS instrument was taken offline for an annual calibration. Comparision of the December 19, 2007 annual calibration with the previous annual calibration done on November 8, 2006 shows very little change in the instrument sensitivity over 2007. From our analysis, there is effectively no change in the silicon spectrometer sensitivity from 400 to 981 nanometers. The InGaAs spectrometer shows a slight decrease in sensitivity of 1 to 2% over the wavelength range of 982 to 2150 nanometers, which is within our expected error range. Characterization of the change in sensitivity from 350 to 400 nanometers over the year is a bit more difficult to determine and maybe greater than our expected error of 2%. The science team at the University of Colorado is currently working on this problem. |
Measurements: | sgpswsC1.b1:
sgpswsauxC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
04/01/2008 | 0000 | 10/16/2008 | 0000 |
Subject: | SGP/SWS/C1 - Temperature instability of InGaAs detector |
DataStreams: | sgpswsC1.b1, sgpswsauxC1.b1 |
Description: | During this time period the SWS experienced a problem with the temperature control InGaAs detector (for wavelength from 900-2200 nm). The problem was initially infrequent but gradually increased in frequency and duration until it was chronic and nearly continual. All data from the InGaAs during affected period is bad and unusable, but data from the Si detector (300 nm to 900 nm) is unaffected. Affected periods are easily discerned from the InGaAs_spect_temp (InGaAs spectrometer temperature) field in the sgpswsauxC1.b1 datastream. When the spectrometer is behaving properly this temperature will be held steady to a value between -9.5 and -10.7 C. When the temperature behaves erratically the InGaAs data is unusable. However the Si data is unaffected. The spectrometer connectors were disconnected and all contacts cleaned. The problem has not reappeared. |
Measurements: | sgpswsC1.b1:
sgpswsauxC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
06/01/2006 | 0000 | 06/01/2009 | 0000 |
Subject: | SGP/SWS/C1 - Contamination by scattered light on optics. |
DataStreams: | sgpswsC1.b1 |
Description: | It has been observed that the zenith radiance measurement is susceptible to contamination from light scattered off of the internal optics. This problem is most serious when measuring clear sky radiance in the presence of direct sun. Under this worst case condition, it affects short wavelengths (less than 500 nm) at a few percent level, moderate wavelengths (500-800nm) between a few percent and 10-20%, and longer wavelengths up to 80% or more. Chui and Marshak have demonstrated some success at identifying isolated affected data using the TSI to find cases of scattered clouds. In general though, one must treat the zenith radiance data with considerable caution whenever direct solar radiance is likely to be present. It is anticipated that the SWS zenith radiance for overcast skies is not significantly affected. The instrument has been renovated by adding a sun shade to prevent direct sunlight from striking the optics. An additional set of baffles further restricts the field of view, further reducing the potential for even off-axis bright clouds to affect the zenith measurement. Data taken after June 2009 is considered to be free of contamination. |
Measurements: | sgpswsC1.b1:
|