| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D030214.1 | SGP/MWR/B4/C1 - LOS cycle skipping | sgpmwrlosC1.b1, sgpmwrlosB4.a1, sgpmwrlosB4.b1, sgpmwrlosC1.a1 |
| D030312.10 | SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures | sgp1mwravgC1.c1, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosC1.b1 |
| D030822.1 | SGP/MWR/C1 - Incorrect min and max values | sgpmwrlosC1.b1 |
| D040824.1 | SGP/MWR/C1 - Wet window flag "on" more frequently than expected | sgpmwrlosC1.a1, sgpmwrlosC1.b1 |
| D050722.1 | SGP/MWR/C1 - REPROCESS - Revised Retrieval Coefficients | sgp1mwravgC1.c1, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgpqmemwrcolC1.c1 |
| D051011.6 | SGP/MWR/C1 - New software version (4.15) installed | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/31/2002 | 2034 | 11/05/2002 | 1815 |
| Subject: | SGP/MWR/B4/C1 - LOS cycle skipping |
| DataStreams: | sgpmwrlosC1.b1, sgpmwrlosB4.a1, sgpmwrlosB4.b1, sgpmwrlosC1.a1 |
| Description: | When MWR software version 4.12 was installed at the SGP, it was observed that the MWRs at CF and BF4 skip line-of-sight (LOS) observing cycles. In LOS mode, the software begins an observing cycle at 0, 20, and 40 seconds after the minute to provide 3 LOS cycles per minute. If a cycle is delayed so that it takes more than 20 seconds to complete, then the next start time is missed, the cycle is skipped, and the data that would have been acquired are lost. It was demonstrated that the interaction with the IRT at CF slowed the MWR observing cycle noticeably and contributed significantly to the LOS cycle skipping. The IRT was removed from the MWR on 5 November 2002 and the LOS cycle skipping at the CF was resolved. The IRT data are now available in a new separate datastream: sgpirtC1.a1 (and soon sgpirt2sC1.a1). The BF4 cycle skipping may have resulted from a combination of an additional air temperature sensor on this instrument and the use of a fiber optic cable. However, the cycle skipping on this instrument appears to have abated without modifications to the instrument configuration. |
| Measurements: | sgpmwrlosB4.b1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
sgpmwrlosB4.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/17/1999 | 1800 | 07/31/2002 | 2034 |
| Subject: | SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures |
| DataStreams: | sgp1mwravgC1.c1, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosC1.b1 |
| Description: | Several related and recurring problems with the SGP MWRs have been reported dating back to 1999. These problems were due to the occurrence of blackbody signals (in counts) that were half of those expected. The symptoms included noisy data (especially at Purcell), spikes in the data (especially at Vici), negative brightness temperatures, and apparent loss of serial communication between the computer and the radiometer, which results in a self-termination of the MWR program (especially at the CF). Because these all initially appeared to be hardware-related problems, the instrument mentor and SGP site operations personnel (1) repeatedly cleaned and replaced the fiber optic comm. components, (2) swapped radiometers, (3) sent radiometers back to Radiometrics for evaluation (which has not revealed any instrument problems), and (4) reconfigured the computer's operating system. Despite several attempts to isolate and correct it, the problem persisted. It became apparent that some component of the Windows98 configuration conflicted with the DOS-based MWR program or affected the serial port or the contents of the serial port buffer. This problem was finally corrected by upgrading the MWR software with a new Windows-compatible program. |
| Measurements: | sgp5mwravgC1.c1:
sgp1mwravgC1.c1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/18/2002 | 0000 | 02/10/2003 | 2359 |
| Subject: | SGP/MWR/C1 - Incorrect min and max values |
| DataStreams: | sgpmwrlosC1.b1 |
| Description: | The values of valid_min and valid_max applied to fields tkxc and tknd were incorrect. They should be 303 and 333, respectively. |
| Measurements: | sgpmwrlosC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/01/1999 | 0000 | 12/21/1999 | 2359 |
| 11/10/2000 | 0000 | 12/08/2000 | 2359 |
| 01/26/2001 | 0000 | 03/05/2001 | 2359 |
| 12/18/2001 | 0000 | 12/31/2001 | 2359 |
| 02/11/2002 | 0000 | 02/28/2002 | 2359 |
| 02/19/2003 | 0000 | 03/26/2003 | 2359 |
| 10/15/2003 | 0000 | 11/03/2003 | 2359 |
| Subject: | SGP/MWR/C1 - Wet window flag "on" more frequently than expected |
| DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1 |
| Description: | The wet window flag was set "on" more frequently than expected during the time periods specified. This indicates the heater has been running more than necessary. In most instances the moisture sensitivity was adjusted at the end of these periods. |
| Measurements: | sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/16/2002 | 2000 | 06/28/2005 | 2300 |
| Subject: | SGP/MWR/C1 - REPROCESS - Revised Retrieval Coefficients |
| DataStreams: | sgp1mwravgC1.c1, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgpqmemwrcolC1.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 as follows (BCR 456): SGP/C1 (Lamont) 4/16/2002, 2000 SGP/B1 (Hillsboro) 4/12/2002, 1600 SGP/B4 (Vici) 4/15/2002, 2300 SGP/B5 (Morris) 4/15/2002, 2300 SGP/B6 (Purcell) 4/16/2002, 2200 SGP/E14(Lamont) 4/16/2002, 0000 NSA/C1 (Barrow) 4/25/2002, 1900 NSA/C2 (Atqasuk) 4/18/2002, 1700 TWP/C1 (Manus) 5/04/2002, 0200 TWP/C2 (Nauru) 4/27/2002, 0600 TWP/C3 (Darwin) inception The MONORTM-based retrieval coefficients became active as follows (BCR 984): SGP/C1 (Lamont) 6/28/2005, 2300 SGP/B1 (Hillsboro) 6/24/2005, 2100 SGP/B4 (Vici) 6/24/2005, 2100 SGP/B5 (Morris) 6/24/2005, 2100 SGP/B6 (Purcell) 6/24/2005, 1942 SGP/E14(Lamont) 6/28/2005, 2300 NSA/C1 (Barrow) 6/29/2005, 0000 NSA/C2 (Atqasuk) 6/29/2005, 0000 TWP/C1 (Manus) 6/30/2005, 2100 TWP/C2 (Nauru) 6/30/2005, 2100 TWP/C3 (Darwin) 6/30/2005, 2100 PYE/M1 (Pt. Reyes) 4/08/2005, 1900** ** At Pt. Reyes, the original retrieval coefficients implemented in March 2005 were based on a version of the Rosenkranz model that had been modified to use the HITRAN half-width at 22 GHz and to be consistent with the water vapor continuum in MONORTM. These retrievals yield nearly identical results to the MONORTM retrievals. Therefore the Pt. Reyes data prior to 4/08/2005 may not require reprocessing. |
| Measurements: | sgp5mwravgC1.c1:
sgpmwrtipC1.a1:
sgpqmemwrcolC1.c1:
sgp1mwravgC1.c1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/31/2002 | 2027 | 08/04/2005 | 1959 |
| Subject: | SGP/MWR/C1 - New software version (4.15) installed |
| DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
| Description: | A problem began with the installation of MWR.EXE version 4.12 in July 2002. The software had been upgraded from a "DOS" to a "Windows"-compiled program to address an earlier problem. The software upgrade corrected the earlier problem but introduced a new one that caused line-of-sight observing cycles to be skipped, a 15% reduction in the number of tip curves, and saturation of CPU usage. Software versions 4.13 and 4.14 also produced these problems. The new MWR software, version 4.15, was installed on 08/04/2005. As a consequence of this upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s. |
| Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|