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 - 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)

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/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)

NSA/MWR/C1 - Software Change

The MWR operating software was changed on 16 November 1998 to provide additional 
functionality as described below. This change affects the format of the raw and ingested data. 
   
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.

• Ambient temperature(tkair)
• (tknd)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)

• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• (tknd)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Ambient temperature(tkair)

• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• (tknd)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Ambient temperature(tkair)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)

NSA/MWR/C1 - Spikes in PWV data

The PWV data began exhibiting a pattern of large (~5 cm) spikes which exponetially degrade 
to normal values. The problem is due to a fault in the serial or fiber optic data 
communication. This pattern began intermittent occurrence on 4/9/98 but it dominates the data 
by 5/1/98.

• MWR column precipitable water vapor(vap)

• MWR column precipitable water vapor(vap)

NSA/MWR/C1 - Spikes in PWV data

After reinstallation of repaired MWR #20, PWV data began exhibiting a pattern of large (~5 
cm) spikes which exponetially degrade to normal values. The problem was due to a fault 
in the serial or fiber optic data communication.

This pattern began intermittant ocurrance on 8/15/98 but it dominates the data by 9/6/98.

• 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 - Reprocess: incorrect calibrations

MWR #17 was placed in service while MWR #20 was being repaired by the manufacturer.  The 
data need to be reprocessed with calibration coefficients appropriate for this instrument.

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

• 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)
• (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 blac2body+noise injection signal(bbn31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz sky signal(sky31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Ambient temperature(tkair)
• 31.4 GHz blackbody(bb31)
• Blackbody kinetic temperature(tkbb)
• lon(lon)
• base time(base_time)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• MWR column precipitable water vapor(vap)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Time offset of tweaks from base_time(time_offset)
• 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)

• MWR column precipitable water vapor(vap)
• Time offset of tweaks from base_time(time_offset)
• lat(lat)
• lon(lon)
• 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)
• Dummy altitude for Zeb(alt)
• IR Brightness Temperature(ir_temp)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• base time(base_time)