SGP/MWR/B6 - High noise level, poor calibration

The data from this instrument (serial number 18) have become increasingly noisy, most 
likely due to a failing local oscillator.  A consequence of this increased noise level has 
been few valid calibration scans ("tip curves") since 1 April 2002: during the period 26-31 
March 2002 1496 valid tip curves were acquired, whereas only 729 were acquired during 
April, 387 during May, 143 during June, 243 during July.  As a result, the calibration was 
not as well-maintained as usual.  The measured brightness temperatures and retrieved 
precipitable water vapor and liquid water path should be regarded as suspect.  The instrument 
was replaced with serial number 04 on 2 August 2002.

• Temperature correction coefficient at 31.4 GHz(tc31)
• 23.8 GHz Blackbody signal(bb23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz sky signal(sky31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 23.8 GHz sky signal(sky23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Averaged total liquid water along LOS path(liq)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Sky brightness temperature at 23.8 GHz(tbsky23)

• 23.8 GHz sky signal(sky23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 23.8 GHz sky+noise injection signal(23skyn)
• 23.8 GHz Blackbody signal(23bb)
• Averaged total liquid water along LOS path(liq)
• 31.4 GHz blackbody(bb31)
• 31.4 GHz blackbody(31bb)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 23.8 GHz sky signal(23sky)
• 23.8 GHz Blackbody signal(bb23)
• 23.8 GHz sky brightness temperature(23tbsky)
• Noise injection temp at nominal temperature at 23.8 GHz(noise_injection_temp_23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky+noise injection signal(31skyn)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz blackbody+noise injection signal(31bbn)
• Temperature correction coefficient at 31.4 GHz(temperature_correction_coef_31)
• 23.8 GHz blackbody+noise injection signal(23bbn)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(noise_injection_temp_31)
• 31.4 GHz noise injection brightness temperature(31unoise)
• 31.4 GHz sky signal(sky31)
• 31.4 GHz sky brightness temperature(31tbsky)
• Temperature correction coefficient at 23.8 GHz(temperature_correction_coef_23)
• 23.8 GHz noise injection brightness temperature(23unoise)
• 31.4 GHz sky signal(31sky)
• 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 23.8 GHz adjusted to tkbb(tnd23)
• Averaged total liquid water along LOS path(liq)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• MWR column precipitable water vapor(vap)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 23.8 GHz Blackbody signal(bb23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• 31.4 GHz sky brightness temperature(31tbsky)
• 31.4 GHz sky signal(sky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz sky brightness temperature(23tbsky)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 23.8 GHz sky signal(sky23)
• 23.8 GHz blackbody+noise injection signal(bbn23)

SGP/MWR/B6 - Instrument replaced, calibration incorrect

MWR serial number 18 was replaced with MWR serial number 04 at 1652 on 2 Aug 2002.  
Between this time and 2214, when a sufficient number of new tip curves were acquired to update 
the calibration, the old calibration (for serial number 18) was used.  During this period 
the data are incorrect.

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

• Dummy altitude for Zeb(alt)
• Fraction of data in averaging interval flagged by Dynamic Linear Model as poten(dlm_flag_fraction)
• 31.4 GHz sky brightness temperature(31tbsky)
• Number of points included in the ir_temp ensemble(num_obs_irt)
• Standard deviation about the mean for the total water vapor amount(vap_sdev)
• Standard deviation about the mean for the 23.8 GHz sky brightness temperature(tbsky23_sdev)
• lon(lon)
• base time(base_time)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Standard deviation about the mean for the IR brightness temperature(ir_temp_sdev)
• Averaged total liquid water along LOS path(liq)
• Number of data points averaged for 23tbsky, 31tbsky, vap & liq(num_obs)
• Number of contiguous periods in averaging interval flagged by Dynamic Linear Mo(dlm_flag_periods)
• Fraction of data in averaging interval with water on Teflon window(water_flag_fraction)
• Standard deviation about the mean for the total liquid water amount(liq_sdev)
• Time offset of tweaks from base_time(time_offset)
• lat(lat)
• Number of contiguous periods in averaging interval with water on Teflon window(water_flag_periods)
• 23.8 GHz sky brightness temperature(23tbsky)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Number of data points averaged for ir_temp(num_obs_ir)
• IR Brightness Temperature(ir_temp)
• Standard deviation about the mean for the 31.4 GHz sky brightness temperature(tbsky31_sdev)
• MWR column precipitable water vapor(vap)

• Mixer kinetic (physical) temperature(tkxc)
• Which LOS configuration(losn)
• Actual elevation angle(actel)
• 23.8 GHz sky+noise injection signal(23skyn)
• 23.8 GHz Blackbody signal(23bb)
• Averaged total liquid water along LOS path(liq)
• 31.4 GHz blackbody(bb31)
• Time offset of tweaks from base_time(time_offset)
• 23.8 GHz sky brightness temperature(23tbsky)
• Noise injection temp at nominal temperature at 23.8 GHz(noise_injection_temp_23)
• 31.4 GHz blackbody+noise injection signal(31bbn)
• Temperature correction coefficient at 31.4 GHz(temperature_correction_coef_31)
• 23.8 GHz blackbody+noise injection signal(23bbn)
• IR Brightness Temperature(ir_temp)
• Noise injection temp at nominal temperature at 31.4 GHz(noise_injection_temp_31)
• Ambient temperature(tkair)
• 23.8 GHz noise injection brightness temperature(23unoise)
• base time(base_time)
• 23.8 GHz sky signal(sky23)
• Actual Azimuth(actaz)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(31bb)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 23.8 GHz sky signal(23sky)
• 23.8 GHz Blackbody signal(bb23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky+noise injection signal(31skyn)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Blackbody kinetic temperature(tkbb)
• lon(lon)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• (tknd)
• 31.4 GHz noise injection brightness temperature(31unoise)
• 31.4 GHz sky signal(sky31)
• 31.4 GHz sky brightness temperature(31tbsky)
• Temperature correction coefficient at 23.8 GHz(temperature_correction_coef_23)
• Dummy altitude for Zeb(alt)
• 31.4 GHz sky signal(31sky)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• lat(lat)

• Time offset of tweaks from base_time(time_offset)
• Blackbody kinetic temperature(tkbb)
• base time(base_time)
• Averaged total liquid water along LOS path(liq)
• IR Brightness Temperature(ir_temp)
• Temperature correction coefficient at 23.8 GHz(tc23)
• MWR column precipitable water vapor(vap)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Actual elevation angle(actel)
• Sky Infra-Red Temperature(sky_ir_temp)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz sky brightness temperature(23tbsky)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 23.8 GHz sky signal(sky23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• lon(lon)
• (tknd)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Actual Azimuth(actaz)
• Mixer kinetic (physical) temperature(tkxc)
• Ambient temperature(tkair)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 23.8 GHz Blackbody signal(bb23)
• 31.4 GHz sky brightness temperature(31tbsky)
• 31.4 GHz sky signal(sky31)

SGP/MWR/B6 - Instrument replaced, calibration updating

Following replacement of the MWR at B6, an automatically and continuously upated median 
calibration value was used based on data acquired during this period.  After this period, 
sufficient tip curves were available to automatically and continuously determine and 
account for the temperature dependence of the calibration.

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

• Dummy altitude for Zeb(alt)
• Fraction of data in averaging interval flagged by Dynamic Linear Model as poten(dlm_flag_fraction)
• 31.4 GHz sky brightness temperature(31tbsky)
• Number of points included in the ir_temp ensemble(num_obs_irt)
• Standard deviation about the mean for the total water vapor amount(vap_sdev)
• Standard deviation about the mean for the 23.8 GHz sky brightness temperature(tbsky23_sdev)
• lon(lon)
• base time(base_time)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Standard deviation about the mean for the IR brightness temperature(ir_temp_sdev)
• Averaged total liquid water along LOS path(liq)
• Number of data points averaged for 23tbsky, 31tbsky, vap & liq(num_obs)
• Number of contiguous periods in averaging interval flagged by Dynamic Linear Mo(dlm_flag_periods)
• Fraction of data in averaging interval with water on Teflon window(water_flag_fraction)
• Standard deviation about the mean for the total liquid water amount(liq_sdev)
• Time offset of tweaks from base_time(time_offset)
• lat(lat)
• Number of contiguous periods in averaging interval with water on Teflon window(water_flag_periods)
• 23.8 GHz sky brightness temperature(23tbsky)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Number of data points averaged for ir_temp(num_obs_ir)
• IR Brightness Temperature(ir_temp)
• Standard deviation about the mean for the 31.4 GHz sky brightness temperature(tbsky31_sdev)
• MWR column precipitable water vapor(vap)

• Mixer kinetic (physical) temperature(tkxc)
• Which LOS configuration(losn)
• Actual elevation angle(actel)
• 23.8 GHz sky+noise injection signal(23skyn)
• 23.8 GHz Blackbody signal(23bb)
• Averaged total liquid water along LOS path(liq)
• 31.4 GHz blackbody(bb31)
• Time offset of tweaks from base_time(time_offset)
• 23.8 GHz sky brightness temperature(23tbsky)
• Noise injection temp at nominal temperature at 23.8 GHz(noise_injection_temp_23)
• 31.4 GHz blackbody+noise injection signal(31bbn)
• Temperature correction coefficient at 31.4 GHz(temperature_correction_coef_31)
• 23.8 GHz blackbody+noise injection signal(23bbn)
• IR Brightness Temperature(ir_temp)
• Noise injection temp at nominal temperature at 31.4 GHz(noise_injection_temp_31)
• Ambient temperature(tkair)
• 23.8 GHz noise injection brightness temperature(23unoise)
• base time(base_time)
• 23.8 GHz sky signal(sky23)
• Actual Azimuth(actaz)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(31bb)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 23.8 GHz sky signal(23sky)
• 23.8 GHz Blackbody signal(bb23)
• MWR column precipitable water vapor(vap)
• 31.4 GHz sky+noise injection signal(31skyn)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Blackbody kinetic temperature(tkbb)
• lon(lon)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• (tknd)
• 31.4 GHz noise injection brightness temperature(31unoise)
• 31.4 GHz sky signal(sky31)
• 31.4 GHz sky brightness temperature(31tbsky)
• Temperature correction coefficient at 23.8 GHz(temperature_correction_coef_23)
• Dummy altitude for Zeb(alt)
• 31.4 GHz sky signal(31sky)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• lat(lat)

• Time offset of tweaks from base_time(time_offset)
• Blackbody kinetic temperature(tkbb)
• base time(base_time)
• Averaged total liquid water along LOS path(liq)
• IR Brightness Temperature(ir_temp)
• Temperature correction coefficient at 23.8 GHz(tc23)
• MWR column precipitable water vapor(vap)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Actual elevation angle(actel)
• Sky Infra-Red Temperature(sky_ir_temp)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz sky brightness temperature(23tbsky)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 23.8 GHz sky signal(sky23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• lon(lon)
• (tknd)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Actual Azimuth(actaz)
• Mixer kinetic (physical) temperature(tkxc)
• Ambient temperature(tkair)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 23.8 GHz Blackbody signal(bb23)
• 31.4 GHz sky brightness temperature(31tbsky)
• 31.4 GHz sky signal(sky31)

SGP/MWR/B6 - Incorrect MWR warmup configuration

The local oscillator warm-up delay in the MWR configuration file was set to 
720 milliseconds instead of the typical 100 milliseconds which substantially 
increased the duration of the observing cycle.

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• 31.4 GHz sky signal(tipsky31)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 23.8 GHz sky signal(tipsky23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 23.8 GHz Blackbody signal(bb23)
• 31.4 GHz blackbody(bb31)

• 23.8 GHz sky signal(sky23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• 23.8 GHz Blackbody signal(bb23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky signal(sky31)

• 23.8 GHz Blackbody signal(bb23)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• 31.4 GHz sky brightness temperature(31tbsky)
• 31.4 GHz sky signal(sky31)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz sky brightness temperature(23tbsky)
• MWR column precipitable water vapor(vap)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 23.8 GHz sky signal(sky23)
• 23.8 GHz blackbody+noise injection signal(bbn23)

SGP/MWR/B6 - 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.

• 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)

• 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 31.4 GHz(tbsky31)

SGP/MWR/B6  - 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)

SGP/MWR/B6  - thermal instability

During periods of high ambient temperature, the instrument may have been thermally 
unstable.

• 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)

• 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 31.4 GHz(tbsky31)

SGP/MWR/B6 - Heater problem

When the heater/blower was replaced, the wet_window flag was constantly set high because 
the "moisture threshold voltage" value in the configuration file was not changed. The 
value was corrected for the new heater and the constant flagging stopped.

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

SGP/MWR/B6 - Reprocess: 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 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 SGP.B6 
20020416.2200.  The MONORTM-based retrieval coefficients became active 
at SGP.B6 20050624.1942.

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.

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

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

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

• Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
• Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)

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

SGP/MWR/B6 - New software version (4.15) installed

A problem began with the installation of MWR.EXE version 4.12 in July 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 9/23/2005. As a consequence of this 
upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s.

• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Ambient temperature(tkair)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 31.4 GHz sky signal(tipsky31)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• (tknd)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 23.8 GHz sky signal(tipsky23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 23.8 GHz Blackbody signal(bb23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz blackbody(bb31)
• Blackbody kinetic temperature(tkbb)
• Mixer kinetic (physical) temperature(tkxc)
• Temperature correction coefficient at 31.4 GHz(tc31)

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

SGP/MWR/B6  - Reprocess: wrong retrievals

When the computer and core configuration were upgraded, retrieval coefficients for BF1 
were accidently included in the configuration file.
The correct coefficients for BF6 were applied when the software was upgraded to ver. 4.14 
and the configuration file was updated.

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

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

• Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
• Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)

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

SGP/MWR/B6 - Reprocessed: Corrected calibration

The instrument was overheating so the radiometer temperature set point was increased from 
52 C to 56.5 C. The period between 7/20 and 7/22 has been reprocessed with corrected 
calibration coefficients.  Reprocessed MWRLOS data were archived January 2007.  MWRTIP data 
will not be reprocessed.

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

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

SGP/MWR/B6 - Reprocessed: Corrected calibration

The instrument was overheating so the radiometer temperature set point was increased from 
56.3 C to 57.8 C.  The data have been reprocessed with corrected calibration 
coefficients.  Reprocessed MWRLOS data were archived January 2007.  MWRTIP data will not be 
reprocessed.

• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 23.8 GHz goodness-of-fit coefficient(r23)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• (tknd)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 23.8 GHz sky signal(tipsky23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Mixer kinetic (physical) temperature(tkxc)
• Temperature correction coefficient at 31.4 GHz(tc31)

• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Averaged total liquid water along LOS path(liq)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• MWR column precipitable water vapor(vap)
• Mixer kinetic (physical) temperature(tkxc)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• (tknd)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)

SGP/MWR/B6 - Incorrect rain flag

The rain flag indicator is coming up too often. On 9/11 the SGP technicians checked and 
adjusted the rain sensor sensitivity. The operation seemed successful, bu on 9/18 the flag 
indicator came back up and stayed on too much since.

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

SGP/MWR/B6 - Incorrect mixer kinetic temperature

The mixer kinetic temperature values are incorrect. The mixer temp sensor was on an open 
circuit.

This is a diagnostic variable. The noise diode mount temperature Tknd can be used to 
monitor the thermal stabilization of the instrument

• Mixer kinetic (physical) temperature(tkxc)

• Mixer kinetic (physical) temperature(tkxc)

SGP/MWR/B6 - Reprocessed: Re-calibration

There was a slight change in the calibration of the instrument after it recovered from a 
data outage. 

Data were reprocessed with the following calibration coefficients:
Tnd23_nom = 238.29; Tc23 = 0.024
Tnd31_nom = 221.78; Tc31 = 0.013

The reprocessed data were archived June 2008.

• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Temperature correction coefficient at 31.4 GHz(tc31)

• MWR column precipitable water vapor(vap)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Sky brightness temperature at 31.4 GHz(tbsky31)

SGP/MWR/B6 - Loss of thermal stabilization

Data are erratic due to loss of thermal stabilization of the instrument.

• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Temperature correction coefficient at 31.4 GHz(tc31)

• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• MWR column precipitable water vapor(vap)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz sky signal(sky31)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)