DQR ID | Subject | Data Streams Affected |
---|---|---|
D001122.1 | SGP/MWR/C1 - calibration checks | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D001205.1 | SGP/MWR/C1 - Time drift | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D030902.1 | SGP/MWR/C1 - no air temperature signal | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D041001.3 | SGP/MWR/C1 - Instrument problem | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D041014.1 | SGP/MWR/C1 - thermal instability | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D041117.2 | SGP/MWR/C1 - Reprocess: wrong retrievals | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgpqmemwrcolC1.c1 |
D050203.3 | SGP/MWR/C1 - spare instrument | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D050722.1 | SGP/MWR/C1 - REPROCESS - Revised Retrieval Coefficients | sgp1mwravgC1.c1, sgp5mwravgC1.c1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgpqmemwrcolC1.c1 |
D050915.1 | SGP/MWR/C1 - Instrument noise problem | sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgp1mwravgC1.c1, sgp5mwravgC1.c1 |
D051011.6 | SGP/MWR/C1 - New software version (4.15) installed | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D060717.2 | SGP/MWR/C1 - Spikes in ambient temperature readings | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D070314.2 | SGP/MWR/C1/E14 - Freezing rain-Incorrect rain flag | sgpmwrlosC1.b1, sgpmwrlosE14.b1, sgpmwrtipC1.a1, sgpmwrtipE14.a1 |
D070802.3 | SGP/MWR/C1 - Noisy data | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D071128.2 | SGP/MWR/C1 - Reprocess: Radiometer reinstalled- Please reprocess | sgp5mwravgC1.c1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D081013.5 | SGP/MWR/C1 - Increased noise in 31.4 GHz channel | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
D980507.3 | SGP/MWR/B6/C1 - Instrument moved, tip field of view not clear | sgpmwrtipB6.a0, sgpmwrtipC1.a0, sgpmwrlosB6.a0, sgpmwrlosB6.a1 |
D981204.1 | SGP/MWR/C1 - Erroneous internal temperature | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Start Date | Start Time | End Date | End Time |
---|---|---|---|
02/16/2000 | 2210 | 02/16/2000 | 2250 |
09/21/2000 | 1423 | 09/21/2000 | 1434 |
09/21/2000 | 1506 | 09/21/2000 | 1517 |
09/26/2000 | 1426 | 09/26/2000 | 1434 |
10/02/2000 | 1732 | 10/02/2000 | 1752 |
10/02/2000 | 2052 | 10/02/2000 | 2107 |
10/03/2000 | 1406 | 10/03/2000 | 1421 |
09/06/2001 | 1900 | 09/06/2001 | 2000 |
Subject: | SGP/MWR/C1 - calibration checks |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | The MWR calibration was checked by a cryogenic (liquid nitrogen) blackbody target or (in the case of the Sept 2001 time period) by pointing the mirror at an internal blackbody target. The brightness temperatures and vap and liq retrievals are not representative of the sky/atmosphere. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
05/05/2000 | 1955 | 09/18/2000 | 2145 |
Subject: | SGP/MWR/C1 - Time drift |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | On 9/18/00, I found that the time on the MWR laptop was 1m 21s slow. The Dimension4 utility had last synchronized the time on 5/5/00. Found that the network DNS settings had been disabled. Added the DNS entry for ntp host CF10. Dimension4 synchronized the clock by adding 80.91s. The time had drifted at a rate of -0.59s/day. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
08/22/2003 | 2115 | 09/30/2004 | 1835 |
Subject: | SGP/MWR/C1 - no air temperature signal |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | When the new blower was upgraded by Radiometrics and reinstalled on the MWR, the air temperature sensor failed to properly report. It was determined that the wires carrying the signal to the analog board did not conform to the standard expected by the upgraded blower. The problem was corrected by changing the wiring. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
09/21/2004 | 2114 | 09/24/2004 | 1354 |
09/26/2004 | 2332 | 09/27/2004 | 0317 |
09/27/2004 | 1214 | 09/30/2004 | 1820 |
Subject: | SGP/MWR/C1 - Instrument problem |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | The MWR mixer temperature, blackbody temperature, and moisture flag are incorrect. This began when the instrument was returned to service after the analog board was temporarily removed to check the presence and absence of certain resistors. The board must have been accidently damaged during this process. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
09/30/2004 | 1835 | 10/13/2004 | 2118 |
Subject: | SGP/MWR/C1 - thermal instability |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | The analog board was replaced with a spare (D041001.3) with a reference temperature that was set too low (306 K) so that during periods of high ambient temperature, the instrument became thermally unstable. The problem was corrected when the temperature setting was increased (to 311 K). |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
09/21/2004 | 1643 | 11/11/2004 | 2100 |
Subject: | SGP/MWR/C1 - Reprocess: wrong retrievals |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgpqmemwrcolC1.c1 |
Description: | When the computer and core configuration were upgraded, retrieval coefficients for BF1 were accidently included in the configuration file. The correct coefficients for CF1 were applied when the configuration file was updated. |
Measurements: | sgpmwrtipC1.a1:
sgpqmemwrcolC1.c1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
05/20/2003 | 1558 | 08/22/2003 | 2059 |
Subject: | SGP/MWR/C1 - spare instrument |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | The spare MWR, S.N. 04, was installed while the production instrument, S.N. 10, was returned to the manufacturer for upgrades. |
Measurements: | sgpmwrtipC1.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 |
---|---|---|---|
07/28/2005 | 1400 | 08/05/2005 | 1700 |
Subject: | SGP/MWR/C1 - Instrument noise problem |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1, sgp1mwravgC1.c1, sgp5mwravgC1.c1 |
Description: | Various variables including the mixer temperatures were very noisy. After several attempts to fix the problem, the instrument was taken off line and returned to the manufacturer for repair. |
Measurements: | sgp5mwravgC1.c1:
sgpmwrtipC1.a1:
sgp1mwravgC1.c1:
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:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
07/13/2006 | 1200 | 07/28/2006 | 1600 |
Subject: | SGP/MWR/C1 - Spikes in ambient temperature readings |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | There are intermittent spikes in the Tkair temperature (T ~ 400 K). On 7/28 the sensor was cleaned and the instrument power cycled following a power outage. Readings came back to normal. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
01/12/2007 | 0000 | 01/15/2007 | 0000 |
Subject: | SGP/MWR/C1/E14 - Freezing rain-Incorrect rain flag |
DataStreams: | sgpmwrlosC1.b1, sgpmwrlosE14.b1, sgpmwrtipC1.a1, sgpmwrtipE14.a1 |
Description: | Between 01/12 and 01/15 brightness temperatures show high values (Tb > 100 K) indicative of rain, however the wet_window flag is 0 (indicative of no rain). During that time there where freezing conditions with ice pellets that were not detected by the sensor. The high brightness temperatures may be due to melting ice on the window. |
Measurements: | sgpmwrtipE14.a1:
sgpmwrtipC1.a1:
sgpmwrlosE14.b1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
07/14/2007 | 0000 | 08/03/2007 | 1508 |
Subject: | SGP/MWR/C1 - Noisy data |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | Since 7/14 the MWR is experiencing intermittent periods of increased noise. The cause for this is under investigation. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
11/19/2007 | 2136 | 11/22/2007 | 1400 |
Subject: | SGP/MWR/C1 - Reprocess: Radiometer reinstalled- Please reprocess |
DataStreams: | sgp5mwravgC1.c1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | After the radiometer was reinstalled it had to update the calibration coefficients. Data will be reprocessed |
Measurements: | sgp5mwravgC1.c1:
sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
05/01/2008 | 0000 | 11/30/2008 | 2300 |
Subject: | SGP/MWR/C1 - Increased noise in 31.4 GHz channel |
DataStreams: | sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | The 31.4 GHz channel has been showing an increased level of noise which results in increased noise in the LWP retrievals. The instrument is tipping and all other parameters seem to be in the range. The elevate noise started in May, but it seems to have become slightly worse after summer. After November the noise level seems to have gone back to normal. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.b1:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
05/01/1998 | 0000 | 05/05/1998 | 0000 |
Subject: | SGP/MWR/B6/C1 - Instrument moved, tip field of view not clear |
DataStreams: | sgpmwrtipB6.a0, sgpmwrtipC1.a0, sgpmwrlosB6.a0, sgpmwrlosB6.a1 |
Description: | During the water vapor IOP in September 1997 it was observed that the ARM MWR reported about 2 mm more water vapor than other sensors. Unlike the 1996 WVIOP, only one ARM MWR was used. To assess the performance of the MWR used during the 1997 WVIOP, it was recomended that another ARM MWR should be operated in close proximity to the unit at the SGP central facility. Last week SGP operations staff set up MWR 18, normally located at BF-6 (Purcell), in proximity to MWR 10 at the SGP central facility near Lamont, OK. I travelled to Oklahoma to carry out the comparison of the radiometers. Although it rained or was cloudy until Thursday evening, I was able to make a good comparison. The results are summarized below and in the attached GIF plots. On or a about 20 November 1996 (after the 1996 WVIOP) a 10-m tower was erected approximately 200 feet south of the MWR and directly in the plane of the elevation scan used during tip mode. The top of the tower has an elevation angle of about 10 degrees relative to the radiometer position, whereas the lowest tip angle is 19.5 degrees. However, the first sidelobe in the antenna pattern is 11 degrees from center, so it is possible that the tips were influenced by the tower. Looking back at the calibration data it appears that the quality of the tips deteriorated in 1997. I had to lower the acceptance criterion from R=0.995 to R=0.990 in order to get a reasonable number of tips. (R is the correlation coefficient of the Langley regression of opacity vs airmass; 1.00=perfect co-linearity.) The situation worsened as the ambient temperature increased, which supports the notion of tower contamination. Much to my surprise, rotating the radiometers 90 degrees so that they could not view the tower did not greatly affect the derived brightness temperatures or PWV and LWP estimates, although the quality of the tip curves did dramatically increase (e.g. the R values were in the range 0.995-0.999). This is revealed in plot1.gif which presents the PWV and LWP dervied from both radiometers and the PWV from the radiosondes. NOTE that the difference between the radiometers and the radiosondes depends strongly on the sonde calibration lots. Note that during the 1997 WVIOP sondes from lots 733 and 726 (weeks 33 and 26 of 1997) were launched. These were very close in time to lots 729, 730 and 735 launched last week which also showed a bias of about -2 mm relative to the MWR. The brightness temperatures derived from the tip curves are presented in plot2.gif. These reveal a slight offset (0.3-0.5 K) in both channels, with MWR 18 (Purcell) higher. I suspect that this may be due to the temperature sensors in the blackbody target. In MWR 18 the two sensors are offset by about 0.75 K, whereas in MWR 10 the offset is only about 0.25 K. I use the average of the two readings in calculating the brightness temperature, so an error of 0.3-0.5 K could result if one sensor is high. The sondes exhibit the same batch-dependent behavior as in plot1.gif. Brightness temperature differences at each pair of elevation angles are presented in plot3a.gif and plot3b.gif for MWR 10 and 18 respectively. The orientation of the radiometer and the direction of the differences are printed along the bottom of the plot. For example, E-W means that the scan is from east to west and the differences are east minus west. These reveal several things: 1. I located the radiometers too close to each other in the north-south plane. When both radiometers were scanning East-West, MWR 18, which was east of MWR 10, was in the sidelobe of the MWR 10 antenna pattern, as indicated by the large differences for 10 when the differences for 18 were small. Rotating MWR 10 180 degrees to scan west-east moved its antenna about 2 feet farther north and its differences dramatically decreased and were the mirror image of those from MWR 18. 2. Although the polycarbonate foam window on MWR 10 was significantly weathered and more so on one side than the other, replacing the window did not noticeably affect the measurements. (I initially thought that the window was the cause of the large differences and later discovered that the radiometers were too close together.) 3. Significant east-west or north-south differences resulted in only small (~0.5 K) offsets in the derived brightness temperatures. (Note the change in brightness temperature differences in plot3a.gif at 05:00 on day 121 when MWR 10 was rotated 180 degrees to scan west-east and then examine the corresponding changes in TB or PWV and LWP in plot1.gif and plot2.gif.) The results of the September 1997 and May 1998 calibrations for MWR 10 are presented below. Date R min N tips TND23 tc23 dev23 TND31 tc31 dev31 (K) (K/K) (K) (K) (K/K) (K) 26-30 Sep 97 0.990 408 205.45 -0.079 0.36 191.02 -0.031 0.20 01-04 May 98 0.995 2768 205.27 -0.074 0.39 189.41 -0.011 0.27 There appears to have been a significant change in the 31 GHz (liquid- sensing) channel calibration since the IOP. However, the 23 GHz (vapor-sensing) channel calibration does not appear to have changed. Moreover, reprocessing the September 1997 data using the May 1998 calibration reduces the PWV by only about 0.4-0.5 mm but introduces a significant bias (0.04 mm) in the LWP. Thus, the May 1998 calibration does not appear to be appropriate for September 1997. The bottom line is that there does NOT appear to be any problem with MWR 10 at the Central Facility. The agreement between the two MWRs is within the manufacturer's specification, although it does appear that one of the temperature sensors in the blackbody target on MWR 18 may need to be replaced or recalibrated. From now on tip curves at the CF should be done west-east rather than north-south to avoid any possible influence of the SIRS tower. |
Measurements: | sgpmwrlosB6.a1:
sgpmwrlosB6.a0:
sgpmwrtipC1.a0:
sgpmwrtipB6.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
10/21/1998 | 1900 | 11/12/1998 | 2200 |
Subject: | SGP/MWR/C1 - Erroneous internal temperature |
DataStreams: | sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipC1.a1 |
Description: | After the new internal temperature sensor was installed it was discovered that the scaling resistor was incorrect. (The 24.9 kohm 0.1% resistor had accidently been replaced with a 24.0 kohm resistor when the analog board was repaired by the manufacturer several years ago.) A resistor having the correct value was installed 981112. |
Measurements: | sgpmwrtipC1.a1:
sgpmwrlosC1.a1:
sgpmwrlosC1.b1:
|