| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D970321.3 | ||
| D980507.3 | SGP/MWR/B6/C1 - Instrument moved, tip field of view not clear | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrtipB6.a0, sgpmwrtipC1.a0 |
| D990106.1 | SGP/MWR/B1/B4/B6/C1 - software change | sgpmwrlosB1.a0, sgpmwrlosB1.a1, sgpmwrlosB4.a0, sgpmwrlosB4.a1, sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipB1.a0, sgpmwrtipB4.a0, sgpmwrtipB6.a0 |
| D990113.1 | SGP/MWR/B1/B4/B5/B6/C1 - software upgrade (version 3.27) | sgpmwrlosB1.a1, sgpmwrlosB4.a1, sgpmwrlosB5.a1, sgpmwrlosB6.a1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipB1.a0, sgpmwrtipB4.a0, sgpmwrtipB5.a0, sgpmwrtipB6.a0 |
| D990916.1 | SGP/MWR/B1/B4/B5/B6 - data file split at 23:59 | sgpmwrlosB1.a1, sgpmwrlosB1.b1, sgpmwrlosB4.a1, sgpmwrlosB4.b1, sgpmwrlosB5.a1, sgpmwrlosB5.b1, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgpmwrtipB1.a1, sgpmwrtipB4.a1, sgpmwrtipB5.a1, sgpmwrtipB6.a1 |
| Start Date | Start Time | End Date | End Time |
|---|
| Subject: | |
| DataStreams: | |
| Description: | |
| Measurements: |
| 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: | sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrtipB6.a0, sgpmwrtipC1.a0 |
| 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.a0:
sgpmwrtipC1.a0:
sgpmwrtipB6.a0:
sgpmwrlosB6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/03/1995 | 0000 | 10/12/1998 | 1900 |
| Subject: | SGP/MWR/B1/B4/B6/C1 - software change |
| DataStreams: | sgpmwrlosB1.a0, sgpmwrlosB1.a1, sgpmwrlosB4.a0, sgpmwrlosB4.a1, sgpmwrlosB6.a0, sgpmwrlosB6.a1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipB1.a0, sgpmwrtipB4.a0, sgpmwrtipB6.a0 |
| Description: | The MWR operating software was changed on 12 October 1998 to provide additional functionality as described below. This change affects the format of the raw and ingested data. NEW FEATURES 1. Faster sampling rate Standard line-of-sight (LOS) observations can now be acquired at 15-second intervals vs. 20-second intervals previously. (The standard LOS cycle is comprised of one sky sample per blackbody sample and gain update.) 2. More flexible sampling strategy Multiple sky observations can be acquired during a LOS cycle, up to 1024 per gain update. This permits sky samples to be acquired at intervals of 2.67 seconds for improved temporal resolution of cloud liquid water variations and better coordination with the millimeter cloud radar during IOPs. 3. Separation of zenith LOS observations from TIP data When the radiometer is in TIP mode, the zenith LOS observations are now extracted, the PWV and LWP computed and reported separately in the output file. This eliminates the periods of missing LOS data during calibration checks/updates. 4. Automatic self-calibration The software now permits the calibration to be updated at specified intervals or continuously. In the first case, LOS mode is automatically changed to TIP mode at user-specified intervals or whenever clear sky conditions occur, the tip data reduced, the calibration updated ,and the radiometer returned to LOS mode without operator intervention. In the second case, the radiometer is continuously is TIP mode until changed by the operator. 5. Graphical user display The graphical display is comprised of a status display, a message display, a temperature plot, a plot of the retrieved PWV and LWP, and (in TIP mode) a plot of the latest tip curves. Editor's Note: The SGP.C1 data were reprocessed in 2004 and enhancement #3 described above was applied to the data prior to Oct 1998. The SGP.BF data are queued for reprocessing as well. |
| Measurements: | sgpmwrtipB1.a0:
sgpmwrlosB1.a1:
sgpmwrlosB4.a0:
sgpmwrlosB6.a0:
sgpmwrlosC1.b1:
sgpmwrtipB6.a0:
sgpmwrlosB1.a0:
sgpmwrtipB4.a0:
sgpmwrlosC1.a1:
sgpmwrlosB4.a1:
sgpmwrlosB6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 07/21/1993 | 1406 | 01/12/1999 | 2359 |
| Subject: | SGP/MWR/B1/B4/B5/B6/C1 - software upgrade (version 3.27) |
| DataStreams: | sgpmwrlosB1.a1, sgpmwrlosB4.a1, sgpmwrlosB5.a1, sgpmwrlosB6.a1, sgpmwrlosC1.a1, sgpmwrlosC1.b1, sgpmwrtipB1.a0, sgpmwrtipB4.a0, sgpmwrtipB5.a0, sgpmwrtipB6.a0 |
| Description: | At 00:00 GMT on 7 January version 3.27 of the MWR operating program was installed and made operational at the SGP central facility (C1). No problems were noted over the next few days and the boundary facility MWRs (B1, B4, B5, B6) were upgraded at 20:00 GMT on 11 January. This version includes a beam width correction I developed as well as providing the capability to automatically level the elevation mirror (that is, to automatically detect and correct offsets in the elevation angle stepper motor position.) On 12 January I discovered that the '486-based MWR computers at B1, B4 and B6 were not executing the system command to move and rename the data files so that the ARM data system could retrieve them. Reducing the length of the storage arrays in the auto-leveling feature from 1000 to 250 resolved the problem. This results in the auto-leveling being based on only 4 hours of clear sky data rather than 16 hours at B5 and C1. This version of the program is 3.28. Version 3.27 (running at B5 and C1) can be installed if and when these computers are upgraded to Pentium-class machines. The improvement in the quality of the tip curves resulting from the auto-leveling has been dramatic: differences in the brightness temperatures at 3 airmasses (19.5 and 160.5 degrees) have been reduced from +/- 5 K to +/- 0.5 K. The goodness-of-fit coefficient for the tip curves has improved from about 0.995 to over 0.998. In order to take full advantage of this improvement to detect and reject cloudy tip curves, the minimum value of the goodness-of-fit coefficient for a valid tip curve has been increased from 0.995 to 0.998. Editor's Note: The SGP.C1 data were reprocessed in 2004 to produce a common DOD for all time. The 1996-1998 data reprocessing included beam width and mirror-leveling corrections, but the data prior to that range did not have these corrections applied. |
| Measurements: | sgpmwrtipB1.a0:
sgpmwrlosB5.a1:
sgpmwrtipB5.a0:
sgpmwrlosB1.a1:
sgpmwrlosC1.b1:
sgpmwrtipB6.a0:
sgpmwrtipB4.a0:
sgpmwrlosC1.a1:
sgpmwrlosB4.a1:
sgpmwrlosB6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/29/1998 | 0000 | 08/12/1999 | 2359 |
| Subject: | SGP/MWR/B1/B4/B5/B6 - data file split at 23:59 |
| DataStreams: | sgpmwrlosB1.a1, sgpmwrlosB1.b1, sgpmwrlosB4.a1, sgpmwrlosB4.b1, sgpmwrlosB5.a1, sgpmwrlosB5.b1, sgpmwrlosB6.a1, sgpmwrlosB6.b1, sgpmwrtipB1.a1, sgpmwrtipB4.a1, sgpmwrtipB5.a1, sgpmwrtipB6.a1 |
| Description: | A problem with the MWR operating software has been corrected. However, several files were generated that contain one record of data collected at midnight but labeled with the previous day's date. |
| Measurements: | sgpmwrlosB5.a1:
sgpmwrlosB1.a1:
sgpmwrtipB6.a1:
sgpmwrlosB6.b1:
sgpmwrlosB4.b1:
sgpmwrtipB4.a1:
sgpmwrtipB5.a1:
sgpmwrlosB1.b1:
sgpmwrtipB1.a1:
sgpmwrlosB4.a1:
sgpmwrlosB5.b1:
sgpmwrlosB6.a1:
|
