DQR ID | Subject | Data Streams Affected |
---|
D010202.8 | NSA/MWR/C2 - Wet-window flag incorrectly set | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D010308.1 | NSA/MWR/C2 - Elevated sky brightness temperatures | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D010504.2 | NSA/MWR/C2 - Missing data | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D020824.4 | NSA/MWR/C2 - Instrument Maintenance | nsamwrlosC2.b1 |
D030312.7 | NSA/MWR/C2 - Intermittent Negative Sky Brightness Temperatures | nsamwrlosC2.b1 |
D030724.1 | NSA/MWR/C2 - Thermally unstable | nsamwrlosC2.b1 |
D040102.4 | NSA/MWR/C2 - Heater problem | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D050202.1 | NSA/MWR/C2 - no air temperature signal | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D050725.8 | NSA/MWR/C2 - Reprocessed: Revised Retrieval Coefficients | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D050830.1 | NSA/MWR/C2 - Thermally unstable | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D050928.4 | NSA/MWR/C2 - New software version (4.15) installed | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D060223.1 | NSA/MWR/C2 - Frosting/Condensation | nsamwrC2.00, nsamwrlosC2.b1, nsamwrtipC2.a1 |
D060818.12 | NSA/MWR/C2 - Spikes in air temperature readings | nsamwrlosC2.b1 |
D080512.2 | NSA/MWR/C2 - Possible bias on measurements | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D080811.1 | NSA/MWR/C2 - Occasional thermal instability | nsa5mwravgC2.c1, nsamwrlosC2.b1, nsamwrtipC2.a1 |
D100224.5 | NSA/MWR/C2 - Radiometer unstable | nsamwrlosC2.b1, nsamwrtipC2.a1 |
D100830.2 | NSA/MWR/C2 - Temperature instability | nsamwrlosC2.b1, nsamwrtipC2.a1 |
Subject: | NSA/MWR/C2 - Intermittent Negative Sky Brightness Temperatures |
DataStreams: | nsamwrlosC2.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: | nsamwrlosC2.b1: - Total liquid water along LOS path(liq)
- 31.4 GHz sky brightness temperature(tbsky31)
- Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
- Total water vapor along LOS path(vap)
|
Subject: | NSA/MWR/C2 - Reprocessed: Revised Retrieval Coefficients |
DataStreams: | nsamwrlosC2.b1, nsamwrtipC2.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 water 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 NSA.C2
20020418.1700. The MONORTM-based retrieval coefficients became active
at NSA.C2 20050629.0000.
Note: The NSA.C2 MWRLOS data for 19991018-20050630 have been reprocessed
to apply the MONORTM-based retrievals for all time. The reprocessed data
were archived in March 2007. The TIP data have not been reprocessed. |
Measurements: | nsamwrlosC2.b1: - Total liquid water along LOS path(liq)
- Total water vapor along LOS path(vap)
nsamwrtipC2.a1:
|
Subject: | NSA/MWR/C2 - New software version (4.15) installed |
DataStreams: | nsamwrlosC2.b1, nsamwrtipC2.a1
|
Description: | A problem began with the installation of MWR.EXE version 4.12 in September 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: | nsamwrlosC2.b1: - Temperature, brightness, longwave(ir_temp)
- tkxc
- tc31
- bbn31
- bb23
- tc23
- tnd_nom23
- IR Brightness Temperature(sky_ir_temp)
- sky31
- tnd31
- tkair
- sky23
- Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
- Total water vapor along LOS path(vap)
- tkbb
- Total liquid water along LOS path(liq)
- tknd
- 31.4 GHz sky brightness temperature(tbsky31)
- bbn23
- bb31
- tnd23
- tnd_nom31
nsamwrtipC2.a1: - bbn31
- tkbb
- tipsky23
- tbskytip31
- tnd23I
- vaptip
- tnd31
- tnd_nom23
- tnd31I
- r31
- liqtip
- bb31
- tc23
- tipsky31
- tbskytip23
- tkair
- bbn23
- tnd_nom31
- tknd
- r23
- tkxc
- bb23
- tc31
- tnd23
|
Subject: | NSA/MWR/C2 - Possible bias on measurements |
DataStreams: | nsamwrlosC2.b1, nsamwrtipC2.a1
|
Description: | This instrument was refurbished at the the vendor's facility in 2008 and then sent to the
SGP for side-by-side comparison with another MWR. During the time the instrument was at
the SGP, it was noticed that the 23.8-GHz measurements were slightly warmer than those
from radiometer SN10 operating at the SGP Central Facility. A comparison with radiosonde
measurements confirmed the slight change in the measurements.
An explanation of the bias and comparison with radiosonde measurements and radiometer SN
10 is given in the mentor's monthly data review for the month of April 2008.
Since there aren't radiosondes at NSA.C2, it is difficult to work around this problem.
Based on comparison at the SGP, the bias in the 23.8-GHz channel was quantified to be ~1.5
K. Users can attempt to subtract this amount from the 23.8-GHz measurements.
Alternatively, use the retrieved PWV and LWV keeping in mind that there is a possible overestimation
of PWV of ~1 mm.
On 11/16/2009 after a hardware failure of the radiometer a spare radiometer (SN15) was
installed at the site. |
Measurements: | nsamwrlosC2.b1: - Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
nsamwrtipC2.a1:
|
Subject: | NSA/MWR/C2 - Occasional thermal instability |
DataStreams: | nsa5mwravgC2.c1, nsamwrlosC2.b1, nsamwrtipC2.a1
|
Description: | Between 7/1 and 7/15 the radiometer experienced a few days of thermal instability. From a
review of the data it doesn't appear that the instability has had any major effect. It is
not possible to quantify in detail the effect of the instability due to the lack of
radiosonde sounding, however users are cautioned that a higher uncertainty may be affecting
these data. |
Measurements: | nsamwrlosC2.b1: - tc31
- Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
- Total water vapor along LOS path(vap)
- Total liquid water along LOS path(liq)
- 31.4 GHz sky brightness temperature(tbsky31)
- tc23
- tnd_nom23
- tnd_nom31
nsamwrtipC2.a1: - tc23
- tbskytip23
- tbskytip31
- vaptip
- tnd_nom31
- tnd31
- tnd_nom23
- tc31
- liqtip
- tnd23
nsa5mwravgC2.c1: - Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
- Total water vapor along LOS path(vap)
- Total liquid water along LOS path(liq)
- 31.4 GHz sky brightness temperature(tbsky31)
|