| DQR ID | Subject | Data Streams Affected |
|---|
| D021004.17 | TWP/MWR/C3 - Elevated Skybrightness Temperatures | twpmwrlosC3.a1, twpmwrlosC3.b1 |
| D021004.18 | TWP/MWR/C3 - Wet Window Flag not correct | twpmwrlosC3.a1, twpmwrlosC3.b1, twpmwrtipC3.a1 |
| D030312.9 | TWP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures | twpmwrlosC1.b1 |
| D030822.11 | TWP/MWR/C3 - min/max/delta values incorrect | twpmwrlosC3.b1 |
| D040211.4 | TWP/MWR/C2 - thermal instability | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D040220.1 | TWP/MWR/C1 - wrong azimuth | twpmwrlosC1.b1 |
| 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 |
| D050725.11 | TWP/MWR/C3 - Reprocess - Revised Retrieval Coefficients | twpmwrlosC3.a1, twpmwrlosC3.b1, twpmwrtipC3.a1 |
| D050725.9 | TWP/MWR/C1 - Reprocessed: Revised Retrieval Coefficients | twp5mwravgC1.c1, twpmwrlosC1.b1, twpmwrtipC1.a1 |
| D050928.1 | TWP/MWR/C1 - New software version (4.15) installed | twpmwrlosC1.b1, twpmwrtipC1.a1 |
| D050928.2 | TWP/MWR/C2 - New software version (4.15) installed | twpmwrlosC2.b1, twpmwrtipC2.a1 |
| D050928.5 | TWP/MWR/C3 - New software version (4.15) installed | twpmwrlosC3.b1, twpmwrtipC3.a1 |
| D051214.1 | TWP/MWR/C3 - REPROCESS- Updated retrieval coefficients | twpmwrlosC3.b1, twpmwrtipC3.a1 |
| D061121.1 | TWP/MWR/C2 - Missing Data | twpmwrlosC2.b1 |
| Subject: | TWP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures |
| DataStreams: | twpmwrlosC1.b1
|
| Description: | Several related and recurring problems with the 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, spikes in the data, 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.
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 did 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: | twpmwrlosC1.b1: - MWR column precipitable water vapor(vap)
- Sky brightness temperature at 31.4 GHz(tbsky31)
- Sky brightness temperature at 23.8 GHz(tbsky23)
- Averaged total liquid water along LOS path(liq)
|
| 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: - 31.4 GHz sky signal(sky31)
- Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
- Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
- Water on Teflon window (1=WET, 0=DRY)(wet_window)
- Temperature correction coefficient at 31.4 GHz(tc31)
- Temperature correction coefficient at 23.8 GHz(tc23)
- Sky brightness temperature at 23.8 GHz(tbsky23)
- MWR column precipitable water vapor(vap)
- 23.8 GHz sky signal(sky23)
- Sky brightness temperature at 31.4 GHz(tbsky31)
- Averaged total liquid water along LOS path(liq)
twpmwrtipC2.a1: - 31.4 GHz sky signal(tipsky31)
- Temperature correction coefficient at 23.8 GHz(tc23)
- Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
- 23.8 GHz sky signal(tipsky23)
- Water on Teflon window (1=WET, 0=DRY)(wet_window)
- Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
- Temperature correction coefficient at 31.4 GHz(tc31)
|
| 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: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
twpqmemwrcolC2.c1: - Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
- Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)
twp5mwravgC2.c1: - Averaged total liquid water along LOS path(liq)
- MWR column precipitable water vapor(vap)
|
| Subject: | TWP/MWR/C3 - Reprocess - Revised Retrieval Coefficients |
| DataStreams: | twpmwrlosC3.a1, twpmwrlosC3.b1, twpmwrtipC3.a1
|
| 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 was active at TWP.C3 from
inception of the data, 20020227.0151. The MONORTM-based retrieval
coefficients became active at TWP.C3 20050630.2100.
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: | twpmwrlosC3.a1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
twpmwrlosC3.b1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
twpmwrtipC3.a1: - Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
- Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
|
| Subject: | TWP/MWR/C1 - Reprocessed: Revised Retrieval Coefficients |
| DataStreams: | twp5mwravgC1.c1, twpmwrlosC1.b1, twpmwrtipC1.a1
|
| 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.C1
20020504.0200. The MONORTM-based retrieval coefficients became active
at TWP.C1 20050630.2100.
Note: The TWP.C1 data for 19961011-20050630 have been reprocessed to apply the |
| Measurements: | twpmwrlosC1.b1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
twp5mwravgC1.c1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
twpmwrtipC1.a1: - Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
- Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
|