DQR ID | Subject | Data Streams Affected |
---|
D000608.11 | TWP/C2/MPL Detector | twpmplC2.00, twpmplC2.a1, twpmplcmask1clothC2.c1, twpmplnor1campC2.c1, twpmplsmask1clothC2.c1 |
D000615.2 | TWP/C2/MPL Data Gap | twpmplcmask1clothC2.c1, twpmplnor1campC2.c1, twpmplsmask1clothC2.c1 |
D000615.3 | TWP/C2/MPL Data gap | twpmplcmask1clothC2.c1, twpmplnor1campC2.c1, twpmplsmask1clothC2.c1 |
D000615.4 | TWP/C2/MPL Data gap | twpmplcmask1clothC2.c1, twpmplnor1campC2.c1, twpmplsmask1clothC2.c1 |
D000615.5 | TWP/C2/MPL Data gap | twpmplcmask1clothC2.c1, twpmplnor1campC2.c1, twpmplsmask1clothC2.c1 |
D000717.1 | TWP/MWR/C1 - Rain on window | twpmwrlosC1.b1, twpmwrtipC1.a1 |
D030312.9 | TWP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures | twpmwrlosC1.b1 |
D040220.1 | TWP/MWR/C1 - wrong azimuth | twpmwrlosC1.b1 |
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 |
D060420.6 | TWP/MWR/C1 - Software Change | twpmwrlosC1.b1 |
D060420.9 | TWP/MWR/C1 - software upgrade (version 3.29) | twpmwrlosC1.b1 |
D061114.2 | TWP/MWR/C1 - Radiometer failure | twpmwrC1.00, twpmwrlosC1.b1, twpmwrtipC1.a1 |
D070105.1 | TWP/MWR/C1 - Missing data | twpmwrlosC1.b1 |
D070412.3 | TWP/MWR/C1/C2 - Sun in the field of view | twpmwrlosC1.b1, twpmwrlosC2.b1, twpmwrtipC1.a1, twpmwrtipC2.a1 |
D070515.4 | TWP/MPL/C2 - Reprocess: Incorrect longitude and altitude reported | twpmplnor1campC2.c1 |
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/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)
|
Subject: | TWP/MWR/C1 - Software Change |
DataStreams: | twpmwrlosC1.b1
|
Description: | The MWR operating software was changed on 27 February 1999 to provide additional
functionality as described below.
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. |
Measurements: | twpmwrlosC1.b1: - (tknd)
- 31.4 GHz blackbody(bb31)
- Mixer kinetic (physical) temperature(tkxc)
- 31.4 GHz sky signal(sky31)
- base time(base_time)
- Sky brightness temperature at 31.4 GHz(tbsky31)
- Dummy altitude for Zeb(alt)
- Actual elevation angle(actel)
- Temperature correction coefficient at 23.8 GHz(tc23)
- Temperature correction coefficient at 31.4 GHz(tc31)
- IR Brightness Temperature(ir_temp)
- 31.4 GHz blac2body+noise injection signal(bbn31)
- Water on Teflon window (1=WET, 0=DRY)(wet_window)
- MWR column precipitable water vapor(vap)
- 23.8 GHz blackbody+noise injection signal(bbn23)
- Ambient temperature(tkair)
- Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
- Sky brightness temperature at 23.8 GHz(tbsky23)
- Time offset of tweaks from base_time(time_offset)
- Averaged total liquid water along LOS path(liq)
- Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
- Sky Infra-Red Temperature(sky_ir_temp)
- Actual Azimuth(actaz)
- 23.8 GHz Blackbody signal(bb23)
- 23.8 GHz sky signal(sky23)
- lon(lon)
- Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
- Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
- Blackbody kinetic temperature(tkbb)
- lat(lat)
|