| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D020805.2 | SGP/MWR/B6 - Instrument replaced, calibration incorrect | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgp5mwravgB6.c1 |
| D020805.3 | SGP/MWR/B6 - Instrument replaced, calibration updating | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgp5mwravgB6.c1 |
| D050725.5 | SGP/MWR/B6 - Reprocess: Revised Retrieval Coefficients | sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgpmwrtipB6.a1, sgp5mwravgB6.c1, sgpqmemwrcolB6.c1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/02/2002 | 1652 | 08/02/2002 | 2144 |
| Subject: | SGP/MWR/B6 - Instrument replaced, calibration incorrect |
| DataStreams: | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgp5mwravgB6.c1 |
| Description: | MWR serial number 18 was replaced with MWR serial number 04 at 1652 on 2 Aug 2002. Between this time and 2214, when a sufficient number of new tip curves were acquired to update the calibration, the old calibration (for serial number 18) was used. During this period the data are incorrect. |
| Measurements: | sgpmwrlosB6.b1:
sgp5mwravgB6.c1:
sgpmwrlosB6.a0:
sgpmwrlosB6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/02/2002 | 2144 | 08/04/2002 | 213 |
| Subject: | SGP/MWR/B6 - Instrument replaced, calibration updating |
| DataStreams: | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgp5mwravgB6.c1 |
| Description: | Following replacement of the MWR at B6, an automatically and continuously upated median calibration value was used based on data acquired during this period. After this period, sufficient tip curves were available to automatically and continuously determine and account for the temperature dependence of the calibration. |
| Measurements: | sgpmwrlosB6.b1:
sgp5mwravgB6.c1:
sgpmwrlosB6.a0:
sgpmwrlosB6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/16/2002 | 220 | 06/24/2005 | 1942 |
| Subject: | SGP/MWR/B6 - Reprocess: Revised Retrieval Coefficients |
| DataStreams: | sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgpmwrtipB6.a1, sgp5mwravgB6.c1, sgpqmemwrcolB6.c1 |
| Description: | IN THE BEGINNING (June 1992), the retrieval coefficients used to derive the precipitable water vapor (PWV) and liquid water path (LWP) from the MWR brightness temperatures were based on the Liebe and Layton (1987) water vapor and oxygen absorption model and the Grant (1957) liquid water absorption model. Following the SHEBA experience, revised retrievals based on the more recent Rosenkranz (1998) water vapor and oxygen absorption models and the Liebe (1991) liquid waer absorption model were developed. The Rosenkranz water vapor absorption model resulted a 2 percent increase in PWV relative to the earlier Liebe and Layton model. The Liebe liquid water absorption model decreased the LWP by 10% relative to the Grant model. However, the increased oxygen absorption caused a 0.02-0.03 mm (20-30 g/m2) reduction in LWP, which was particularly significant for low LWP conditions (i.e. thin clouds encountered at SHEBA). Recently, it has been shown (Liljegren, Boukabara, Cady-Pereira, and Clough, TGARS v. 43, pp 1102-1108, 2005) that the half-width of the 22 GHz water vapor line from the HITRAN compilation, which is 5 percent smaller than the Liebe and Dillon (1969) half-width used in Rosenkranz (1998), provided a better fit to the microwave brightness temperature measurements at 5 frequencies in the range 22-30 GHz, and yielded more accurate retrievals. Accordingly, revised MWR retrieval coefficients have been developed using MONORTM, which utilizes the HITRAN compilation for its spectroscopic parameters. These new retrievals provide 3 percent less PWV and 2.6 percent greater LWP than the previous retrievals based on Rosenkranz (1998). Although the MWR data will be reprocessed to apply the new monortm-based retrievals, for most purposes it will be sufficient to correct the data using the following factors: PWV_MONORTM = 0.9695 * PWV_ROSENKRANZ LWP_MONORTM = 1.026 * LWP_ROSENKRANZ The Rosenkranz-based retrieval coefficients became active at SGP.B6 20020416.2200. The MONORTM-based retrieval coefficients became active at SGP.B6 20050624.1942. Note: a reprocessing effort is already underway to apply the Rosenkranz-based retrieval coefficients to all MWR prior to April 2002. An additional reprocessing task will be undertaken to apply the MONORTM retrieval to all MWR data when the first is completed. Read reprocessing comments in the netcdf file header carefully to ensure you are aware which retrieval is in play. |
| Measurements: | sgpmwrtipB6.a1:
sgp5mwravgB6.c1:
sgpmwrlosB6.b1:
sgpqmemwrcolB6.c1:
sgpmwrlosB6.a1:
|