| Start Date | Start Time | End Date | End Time | Data Quality Metric |
|---|---|---|---|---|
| 08/01/1996 | 0000 | 08/31/1996 | 2359 | Does not affect quality |
| Subject: | SGP/MWR/B1/B4/B5/B6/C1 - Thermal Stabilization Adjustment |
| DataStreams: | sgpmwrlosB4.a1, sgp5mwravgB4.c1, sgpmwrlosB5.a1, sgp5mwravgB6.c1, sgp5mwravgB5.c1, sgpmwrlosC1.b1, sgpmwrlosB1.a0, sgpmwrlosB6.a1, sgpmwrlosB1.a1, sgp1mwravgC1.c1, sgpmwrlosB6.a0, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosB4.a0, sgpmwrlosB5.a0, sgp5mwravgB1.c1 |
| Description: | In order to correct a thermal stabilization problem identified earlier I adjusted the thermal set point of the microwave radiometers at the SGP upward from 48-50 deg C to 55 deg C in early August 1996 according to the schedule given below. B6 5 August 1996 C1 6 August 1996 B1 7 August 1996 B5 8 August 1996 Subsequent to making this adjustment the MWRs were put in TIP mode to check on whether the change in set point temperature affected their calibration. Because clear sky conditions were quite intermittent, it is difficult to determine whether the substantial variability in the tip data were attributable to the change in thermal set point. The instrument calibration was not altered in August. Tip data were again collected with these instruments in September prior to the beginning and at the close of the Water Vapor IOP. For example, the calibration of the instrument at the central facility (S/N 10) derived from the September data was essentially the same as that derived from calibration data acquired in February 1996. Although this would lead one to believe that altering the thermal set point did not affect the instrument calibration, it may be that some transient effect was induced. In comparing soundings launched from the central facility with the microwave radiometer there, I noticed that those sondes calibrated in June 1996 consistently reported lower integrated water vapor than the radiometer in July and September (during the IOP) but were in better agreement with the radiometer for the two weeks period immediately after the set point was adjusted. I suspect that adjusting the thermal set point may have temporarily increased the radiometer gain (kelvins/volt) thereby lowering the measured brightness temperature and the retrieved integrated water vapor. It is not clear why a temporary change in gain should occur or even whether it did. But users of the data should be aware that the data from the microwave radiometers at the SGP may be anomalous during August 1996. |
| Suggestions: | |
| Measurements: | sgpmwrlosC1.a1: more
sgpmwrlosC1.b1: more sgpmwrlosB4.a1: more sgp5mwravgC1.c1: more sgp5mwravgB5.c1: more sgp5mwravgB4.c1: more sgp5mwravgB6.c1: more sgp1mwravgC1.c1: more sgp5mwravgB1.c1: more sgpmwrlosB6.a0: more sgpmwrlosB1.a1: more sgpmwrlosB1.a0: more sgpmwrlosB5.a1: more sgpmwrlosB4.a0: more sgpmwrlosB6.a1: more sgpmwrlosB5.a0: more |