NSA/MWR/C2 - Missing data

Data are missing and unrecoverable.

• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• base time(base_time)
• lat(lat)
• Mixer kinetic (physical) temperature(tkxc)
• lon(lon)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Averaged total liquid water along LOS path(liq)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Ambient temperature(tkair)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 31.4 GHz sky signal(sky31)
• Dummy altitude for Zeb(alt)
• Sky Infra-Red Temperature(sky_ir_temp)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz sky signal(sky23)
• 23.8 GHz Blackbody signal(bb23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Time offset of tweaks from base_time(time_offset)
• Blackbody kinetic temperature(tkbb)
• MWR column precipitable water vapor(vap)
• IR Brightness Temperature(ir_temp)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• (tknd)
• 31.4 GHz blackbody(bb31)

• 23.8 GHz blackbody+noise injection signal(bbn23)
• Actual elevation angle(actel)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• lon(lon)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Ambient temperature(tkair)
• Actual Azimuth(actaz)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 31.4 GHz blackbody(bb31)
• (tknd)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Dummy altitude for Zeb(alt)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz Blackbody signal(bb23)
• lat(lat)
• Temperature correction coefficient at 31.4 GHz(tc31)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz sky signal(tipsky23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Blackbody kinetic temperature(tkbb)
• Temperature correction coefficient at 23.8 GHz(tc23)
• base time(base_time)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Time offset of tweaks from base_time(time_offset)

NSA/MWR/C1 - Contamination or Calibration Effect

A short period of odd data occurs in PWV and the LWP.  Its a sudden offset in the data 
values.  Vic Morris suggests it could be a calibration issue as seen before at SGP.  Data 
make a marked change after the events (suggesting the data were questionable prior to this 
time).  No obvious changes in other instruments occur. Some of these effects may coincide 
with operator's preventive maintenance but others are in the middle of the night local 
time and can not be explained by cleaning.

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

NSA/MWR/C1 - Frosting

Spike in PWV and LWP
. Operator reports instrument is frosted. Instrument teflon window was cleaned by 
operator.

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

NSA/MWR/C1 - Instrument maintenance

Installed cold weather insulation on radiometer, required time to thermally stabilize.

• 23.8 GHz sky plus noise injection signal(skyn23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz sky signal(sky23)
• IR Brightness Temperature(ir_temp)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 31.4 GHz sky signal(sky31)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky+noise injection signal(skyn31)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Sky Infra-Red Temperature(sky_ir_temp)
• (tknd)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz noise injection brightness temperature(unoise31)
• 23.8 GHz noise injection brightness temperature(unoise23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Ambient temperature(tkair)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Which LOS configuration(losn)
• (tair)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz Blackbody signal(bb23)

• 31.4 GHz blackbody(bb31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Sky Infra-Red Temperature(sky_ir_temp)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• (tknd)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• IR Brightness Temperature(ir_temp)
• Ambient temperature(tkair)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Blackbody kinetic temperature(tkbb)
• MWR column precipitable water vapor(vap)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 23.8 GHz Blackbody signal(bb23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz sky signal(sky31)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Averaged total liquid water along LOS path(liq)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 23.8 GHz sky signal(sky23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Temperature correction coefficient at 23.8 GHz(tc23)

NSA/MWR/C1 - MWR moved

The MWR data are unreasonable during this period, because it was shutdown and moved by 
operations at this time.

• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz sky plus noise injection signal(skyn23)
• 23.8 GHz sky signal(sky23)
• IR Brightness Temperature(ir_temp)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 31.4 GHz sky signal(sky31)
• 31.4 GHz blackbody(bb31)
• base time(base_time)
• MWR column precipitable water vapor(vap)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky+noise injection signal(skyn31)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Time offset of tweaks from base_time(time_offset)
• Sky Infra-Red Temperature(sky_ir_temp)
• (tknd)
• Actual Azimuth(actaz)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz noise injection brightness temperature(unoise31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 23.8 GHz noise injection brightness temperature(unoise23)
• Actual elevation angle(actel)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Ambient temperature(tkair)
• Blackbody kinetic temperature(tkbb)
• lon(lon)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Which LOS configuration(losn)
• (tair)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz Blackbody signal(bb23)

• Actual elevation angle(actel)
• Actual Azimuth(actaz)
• 31.4 GHz blackbody(bb31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• lat(lat)
• Sky Infra-Red Temperature(sky_ir_temp)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• (tknd)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• IR Brightness Temperature(ir_temp)
• Ambient temperature(tkair)
• Temperature correction coefficient at 31.4 GHz(tc31)
• base time(base_time)
• Blackbody kinetic temperature(tkbb)
• MWR column precipitable water vapor(vap)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 23.8 GHz Blackbody signal(bb23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Time offset of tweaks from base_time(time_offset)
• 31.4 GHz sky signal(sky31)
• lon(lon)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Averaged total liquid water along LOS path(liq)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Dummy altitude for Zeb(alt)
• 23.8 GHz sky signal(sky23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Temperature correction coefficient at 23.8 GHz(tc23)

NSA/MWR/C1 - negative PWV (bad calibration?)

During this time, the PWV drops to slightly negative values.  This could be related to 
calibration issues.

• MWR column precipitable water vapor(vap)

• MWR column precipitable water vapor(vap)

NSA/MWR/C1 - Heater/blower removed

Note that the heater/blower was removed from the MWR during this time.  This may impact 
snow removal from teflon window, thereby affecting the quality of the data between 
cleanings.

• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz sky plus noise injection signal(skyn23)
• 23.8 GHz sky signal(sky23)
• IR Brightness Temperature(ir_temp)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• (tknd)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• 31.4 GHz noise injection brightness temperature(unoise31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 23.8 GHz noise injection brightness temperature(unoise23)
• 31.4 GHz sky signal(sky31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Ambient temperature(tkair)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky+noise injection signal(skyn31)
• Which LOS configuration(losn)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• (tair)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Sky Infra-Red Temperature(sky_ir_temp)
• Mixer kinetic (physical) temperature(tkxc)

• Blackbody kinetic temperature(tkbb)
• MWR column precipitable water vapor(vap)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 31.4 GHz sky signal(sky31)
• Sky Infra-Red Temperature(sky_ir_temp)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• (tknd)
• 23.8 GHz sky signal(sky23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• IR Brightness Temperature(ir_temp)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Ambient temperature(tkair)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Temperature correction coefficient at 23.8 GHz(tc23)

NSA/MWR/C1 - Data spikes, possibly due to cleaning events

Unreasonable spikes occurred, which may be due to cleaning of 
the instrument by the operator.  Other cleaning events did
not result in obvious data spikes and have not been included 
in this report.

• 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)

• 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)

SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures

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.

• 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)

• 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)

NSA/MWR/C1 - min/max/delta values incorrect

The values of valid_min, valid_max, and valid_delta for fields tkxc and tknd were 
incorrect. They should be 303, 333, and 0.5 K, respectively.

• Mixer kinetic (physical) temperature(tkxc)
• (tknd)

NSA/MWR/C2 - Reprocessed: Revised Retrieval Coefficients

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.

• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)

NSA/MWR/C1 - software upgrade (version 3.28)

The MWR operating program was upgraded to version 3.28 on 3 February 1999. This version 
includes a beam width correction as well as providing 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.

• 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)

• 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)