SGP/MWR/C1 - calibration checks

The MWR calibration was checked by a cryogenic (liquid nitrogen) 
blackbody target or (in the case of the Sept 2001 time period)
by pointing the mirror at an internal blackbody target.  The 
brightness temperatures and vap and liq retrievals are not
representative of the sky/atmosphere.

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

• Sky brightness temperature at 31.4 GHz(tbsky31)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Averaged total liquid water along LOS path(liq)

• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)

SGP/MWR/C1 - IRT failure

The IRT was damaged by internal moisture causing sky temperature
measurements that are negatively biased compared to those from
the AERI. IRT#0517 was returned to the manufacturer for repair
and was replaced with spare IRT#1254.

• Sky Infra-Red Temperature(sky_ir_temp)

• Sky Infra-Red Temperature(sky_ir_temp)

SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures

Several related and recurring problems with the SGP 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 (especially at Purcell),
spikes in the data (especially at Vici), 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 (especially at the CF).

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 has 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.

• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)

• Sky brightness temperature at 31.4 GHz(tbsky31)
• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)

• Sky brightness temperature at 23.8 GHz(tbsky23)
• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)

• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Averaged total liquid water along LOS path(liq)

SGP/MWR/C1 - Wet window flag "on" more frequently than expected

The wet window flag was set "on" more frequently than expected during the time periods 
specified.  This indicates the heater has been running more than necessary.  In most 
instances the moisture sensitivity was adjusted at the end of these periods.

• Sky brightness temperature at 31.4 GHz(tbsky31)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Averaged total liquid water along LOS path(liq)

• Averaged total liquid water along LOS path(liq)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)

SGP/MWR/C1 - Missing data

Data are missing and unrecoverable.

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