| DQR ID | Subject | Data Streams Affected |
|---|
| D020424.1 | NSA/METTWRC1 - METTWRCQ DATA REPORTED AS -9999 | nsamettwrC1.a1, nsamettwrC1.b1, nsaorgC1.a1, nsaorgC1.b1, nsapwsC1.a1, nsapwsC1.b1 |
| D020424.2 | NSA/METTWRC1 - METTWRC1 NO DATA COLLECTED FROM TOWER | nsamettwrC1.a1, nsamettwrC1.b1, nsaorgC1.a1, nsaorgC1.b1, nsapwsC1.a1, nsapwsC1.b1 |
| D020610.2 | NSA/METTWR/C1 - Wind Speed data intermittently bad | nsamettwrC1.a1, nsamettwrC1.b1 |
| D020610.7 | NSA/METTWR/C1 - Data missing due to Power Failure | nsamettwrC1.a1, nsamettwrC1.b1 |
| D021017.1 | NSA/MWR/C1 - MWR digital board failure | nsamwrlosC1.a1, nsamwrlosC1.b1 |
| D030312.6 | SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures | nsamwrlosC1.a1, nsamwrlosC1.b1 |
| D030822.7 | NSA/MWR/C1 - min/max/delta values incorrect | nsamwrlosC1.b1 |
| D041213.5 | NSA/SONDE/C1 - Incorrect surface altitude | nsasondeC1.00, nsasondewnpnC1.b1 |
| D050725.7 | NSA/MWR/C1 - Reprocess: Revised Calibration Coefficients | nsa5mwravgC1.c1, nsamwrlosC1.a1, nsamwrlosC1.b1, nsamwrtipC1.a1, nsaqmemwrcolC1.c1 |
| D050928.3 | NSA/MWR/C1 - New software version (4.15) installed | nsamwrlosC1.b1, nsamwrtipC1.a1 |
| D060928.4 | NSA/SONDE/C1 - Increased precision for alt, dp, pres, rh, tdry | nsasondewnpnC1.b1 |
| Subject: | SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures |
| DataStreams: | nsamwrlosC1.a1, nsamwrlosC1.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 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: | nsamwrlosC1.a1: - MWR column precipitable water vapor(vap)
- Sky brightness temperature at 31.4 GHz(tbsky31)
- Averaged total liquid water along LOS path(liq)
- Sky brightness temperature at 23.8 GHz(tbsky23)
nsamwrlosC1.b1: - Sky brightness temperature at 23.8 GHz(tbsky23)
- MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
- Sky brightness temperature at 31.4 GHz(tbsky31)
|
| Subject: | NSA/MWR/C1 - Reprocess: Revised Calibration Coefficients |
| DataStreams: | nsa5mwravgC1.c1, nsamwrlosC1.a1, nsamwrlosC1.b1, nsamwrtipC1.a1, nsaqmemwrcolC1.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 at NSA.C1
20020425.1900. The MONORTM-based retrieval coefficients became active
at NSA.C1 20050629.0000.
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: | nsamwrlosC1.a1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
nsa5mwravgC1.c1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
nsaqmemwrcolC1.c1: - Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)
- Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
nsamwrlosC1.b1: - MWR column precipitable water vapor(vap)
- Averaged total liquid water along LOS path(liq)
nsamwrtipC1.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)
|