| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D000127.1 | TWP/MWR/C2 - Uncertainty in clock time | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D010227.4 | TWP/MWR/C2 - Excessive wet_window flags | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D040211.4 | TWP/MWR/C2 - thermal instability | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D040920.1 | TWP/MWR/C2 - Data collection problem | twpmwrC2.00, twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D050725.10 | TWP/MWR/C2 - Reprocessed: Revised Retrieval Coefficients | twp5mwravgC2.c1, twpmwrlosC2.b1, twpqmemwrcolC2.c1 |
| D050928.2 | TWP/MWR/C2 - New software version (4.15) installed | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D060420.10 | TWP/MWR/C2 - software upgrade (version 3.29) | twpmwrlosC2.b1 |
| D061121.1 | TWP/MWR/C2 - Missing Data | twpmwrlosC2.b1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/06/1998 | 0000 | 07/30/1999 | 2359 |
| Subject: | TWP/MWR/C2 - Uncertainty in clock time |
| DataStreams: | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| Description: | At ARCS2, the MWR computer clock was not being updated because no NTP time service software was installed on the computer. During Nauru99, on 6/24/99, the clock was found to be 3 minutes and 17 seconds fast. Assuming that the time was properly set at installation on 10/26/98 (which is not indicated in the installation report) and never reset until 6/24/99, the rate of time drift on the computer was about +0.8 seconds per day. However, if the time was not reset since integration at AIS on 1/14/98 (which is recorded in my integration notes), then the rate of drift is about +0.4 seconds per day. The computer was replaced and time service started on 7/30/99. |
| Measurements: | twpmwrlosC2.b1:
twpmwrtipC2.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/16/1999 | 0900 | 03/08/1999 | 2100 |
| 11/16/1999 | 0900 | 02/09/2000 | 2100 |
| 12/07/2000 | 0000 | 12/17/2000 | 2359 |
| Subject: | TWP/MWR/C2 - Excessive wet_window flags |
| DataStreams: | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| Description: | The wet_window flag is set high more than expected from the measured value of liquid water path. This may be caused by dew or, if the heater sensivity is slightly misadjusted, by the diurnal variation in ambient temperature. The "wet_window" flag is an indicator of moisture on the MWR window which invalidates the measurements of precipitable water vapor and liquid water path. Sometimes this flag can be incorrectly set high or low if the heater sensivity is slightly misadjusted. The heater adjustment is a resistive device that is dependent on ambient temperature. Another indicator of moisture on the window is unreasonably high ( > 3*liquid_retrieval_rms_accuracy ) values of "liq". |
| Measurements: | twpmwrlosC2.b1:
twpmwrtipC2.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/27/2004 | 1958 | 01/31/2004 | 2059 |
| Subject: | TWP/MWR/C2 - thermal instability |
| DataStreams: | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| Description: | The MWR required an unusually long time to reach thermal stability after a 4-day outage due to a power failure that damaged the blower/heater assembly. Also during this period, the heater, which had been replaced, appears to have been on continously, causing the data to be inappropriately flagged. |
| Measurements: | twpmwrlosC2.b1:
twpmwrtipC2.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/27/2004 | 2000 | 09/24/2004 | 0219 |
| Subject: | TWP/MWR/C2 - Data collection problem |
| DataStreams: | twpmwrC2.00, twpmwrlosC2.b1, twpmwrtipC2.a1 |
| Description: | Large, frequent data gaps occurred due to a failing laptop computer. The problem was corrected when a new computer was installed. |
| Measurements: | twpmwrlosC2.b1:
twpmwrC2.00:
twpmwrtipC2.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/27/2002 | 0600 | 06/30/2005 | 2100 |
| Subject: | TWP/MWR/C2 - Reprocessed: Revised Retrieval Coefficients |
| DataStreams: | twp5mwravgC2.c1, twpmwrlosC2.b1, twpqmemwrcolC2.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). The Rosenkranz-based retrieval coefficients became active at TWP.C2 20020427.0600. The MONORTM-based retrieval coefficients became active at TWP.C2 20050630.2100. Note: The TWP.C2 data for 19981028-20050630 have been reprocessed to apply the MONORTM-based retrievals for all time. The reprocessed data were archived 20061003. |
| Measurements: | twpmwrlosC2.b1:
twpqmemwrcolC2.c1:
twp5mwravgC2.c1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/01/2002 | 2101 | 09/15/2005 | 1424 |
| Subject: | TWP/MWR/C2 - New software version (4.15) installed |
| DataStreams: | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| Description: | A problem began with the installation of MWR.EXE version 4.12 in November 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 9/15/2005. As a consequence of this upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s. |
| Measurements: | twpmwrlosC2.b1:
twpmwrtipC2.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/28/1998 | 0000 | 07/30/1999 | 1200 |
| Subject: | TWP/MWR/C2 - software upgrade (version 3.29) |
| DataStreams: | twpmwrlosC2.b1 |
| Description: | The MWR operating program was upgraded to version 3.29 on 30 July 1999. This version included a beam width correction as well as provided the capability to automatically level the elevation mirror (that is, to automatically detect and correct offsets in the elevation angle stepper motor position.) 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. 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. The data prior to July 30 1999 do not include beam-width and mirror-leveling corrections. |
| Measurements: | twpmwrlosC2.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/02/1998 | 2112 | 11/06/1998 | 2140 |
| 07/02/2000 | 2000 | 07/04/2000 | 0047 |
| 02/09/2002 | 2300 | 02/11/2002 | 2300 |
| 01/23/2004 | 1100 | 01/27/2004 | 1957 |
| 05/27/2005 | 1143 | 05/29/2005 | 2132 |
| Subject: | TWP/MWR/C2 - Missing Data |
| DataStreams: | twpmwrlosC2.b1 |
| Description: | Data are missing and unrecoverable. |
| Measurements: | twpmwrlosC2.b1:
|