NSA/MWR/C1 - Temperature Stabilization of Noise Diode Impaired

On 1/17 we had a big spike in the data and lost temperature stabilization. The instrument 
had problems maintaining the Noise Diode (ND) temperature since. At ambient temperatures 
under about -20 C the ND was not maintaining the set temperature of 30 C. This problem 
was reported in P010122.1.

Fred Solheim recommended on 1/22 that we powercycle the instrument as it looked like the 
instrument CPU had lost the temperature reference.

So we powercycled the instrument on 1/22 @ 20:30 and lost all comumnication to it; after a 
second powercycling the instrument came back on line and the temperature stabilized 
quickly (within a couple of minutes) to the set temperature (30 C)

Fred Solheim reported after the system was restored:
"I've never seen this behavior before. I don't think it was due to the RF deck physically 
hanging temperature, because the recorded temp dropped about 30 C in one observation 
cycle. If this happens again, send the MWR down along with data files for us to look at."

Data collected in the periode 1/17/2001 6:00 to 1/22/2001 21:45 are questionable since it 
is uncertain whether the temperature really was unstable and what really caused the 
problem.

• tbsky31_sdev
• tbsky23_sdev
• Total water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• water_flag_fraction
• ir_temp_sdev
• num_obs_irt
• liq_sdev
• num_obs
• Temperature, brightness, longwave(ir_temp)
• 23.8 GHz sky brightness temperature(tbsky23)
• vap_sdev
• Mean 31.4 GHz sky brightness temperature(tbsky31)

NSA/MWR/C2 - Wet-window flag incorrectly set

The wet window flag is set high more frequently than expected.

• wet_window

NSA/MWR/C2 - Elevated sky brightness temperatures

The MWR was providing unreasonable values of sky brightness temperatures and values of 
precipitable water vapor and liquid water path that were about 10 times larger than 
expected. The problem was corrected when the instrument was power-cycled. The cause of the 
problem is unknown.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)

NSA/MWR/C2 - Missing data

Data are missing and unrecoverable.

• Temperature, brightness, longwave(ir_temp)
• tkxc
• tc31
• base_time
• time_offset
• bbn31
• bb23
• tnd_nom23
• tc23
• sky31
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• tnd31
• tkair
• Altitude above mean sea level(alt)
• sky23
• wet_window
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)
• North latitude(lat)
• tkbb
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• tknd
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• bbn23
• East longitude(lon)
• bb31
• tnd_nom31
• tnd23

SGP/MWR/E14 - calibration check

The MWR calibration was checked by pointing mirror at internal blackbody target.
The brightness temperatures are not representative of the sky.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)
• Mean 31.4 GHz sky brightness temperature(tbsky31)

SGP/MWR/E14 - Upgrade of Arm Core PC Configuration

Upgrade of Arm Core PC configuration to version 2.6B per ECO 407.  Data collection was 
temporarily interrupted.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• tknd
• bbn23
• 23.8 GHz sky brightness temperature(tbsky23)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• bb23
• wet_window
• tnd23
• Altitude above mean sea level(alt)
• Total water vapor along LOS path(vap)
• sky23
• tkair
• tc23
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• North latitude(lat)
• base_time
• bbn31
• East longitude(lon)
• tnd31
• tkbb
• bb31
• tnd_nom31
• tnd_nom23
• sky31
• time_offset
• tc31
• tkxc

SGP/MWR/E14 - Hard disk failure

The hard disk of the MWR laptop failed 7/17 and was replaced 7/20. The ARM
Core PC Configuration and MWR configuration files were installed on the new
hard disk.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• tknd
• bbn23
• 23.8 GHz sky brightness temperature(tbsky23)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• wet_window
• tnd23
• Altitude above mean sea level(alt)
• Total water vapor along LOS path(vap)
• sky23
• tkair
• tc23
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• North latitude(lat)
• base_time
• bbn31
• East longitude(lon)
• tnd31
• tkbb
• tnd_nom31
• tnd_nom23
• sky31
• time_offset
• tc31
• tkxc

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.

• water_flag_periods
• time_offset
• num_obs_irt
• 23tbsky
• Total water vapor along LOS path(vap)
• dlm_flag_fraction
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• tbsky31_sdev
• 23.8 GHz sky brightness temperature(tbsky23)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Temperature, brightness, longwave(ir_temp)
• liq_sdev
• base_time
• North latitude(lat)
• East longitude(lon)
• num_obs_ir
• dlm_flag_periods
• vap_sdev
• ir_temp_sdev
• 31tbsky
• tbsky23_sdev
• Altitude above mean sea level(alt)
• water_flag_fraction
• num_obs

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.

• water_flag_periods
• time_offset
• num_obs_irt
• 23tbsky
• Total water vapor along LOS path(vap)
• dlm_flag_fraction
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• tbsky31_sdev
• 23.8 GHz sky brightness temperature(tbsky23)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Temperature, brightness, longwave(ir_temp)
• liq_sdev
• base_time
• North latitude(lat)
• East longitude(lon)
• num_obs_ir
• dlm_flag_periods
• vap_sdev
• ir_temp_sdev
• 31tbsky
• tbsky23_sdev
• Altitude above mean sea level(alt)
• water_flag_fraction
• num_obs

NSA/MWR/C2 - Instrument Maintenance

Exchange of winter cover caused data corruption.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• sky23
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz sky brightness temperature(tbsky23)
• sky31
• Total water vapor along LOS path(vap)

NSA/MWR/C2 - 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.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)

NSA/MWR/C2 - Thermally unstable

The MWR became thermally unstable during periods when the ambient temperature exceeded 
about 28C. This situation was corrected when the mixer temperature was manually increased to 
about 35C.

Data are suspect when the blackbody temperature, tkbb, exceeds 296 K.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)

SGP/MWR/E14  - 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.

• tknd
• tkxc

SGP/MWR/E14  - thermal instability

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

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)
• Mean 31.4 GHz sky brightness temperature(tbsky31)

NSA/MWR/C2 - Heater problem

The MWR heater did not appear to operate when moisture was present. The heater sensitivity 
was adjusted.

• wet_window

SGP/MWR/E14 - Reprocess: wrong retrievals

When MWR#04 was installed at EF14 (replacing MWR#33), out-of-date retrieval coefficients 
were used in the configuration file.
The correct coefficients were applied when the computer, software, and configuration file 
were upgraded.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Total water vapor along LOS path(vap)

NSA/MWR/C2 - no air temperature signal

When the new blower was upgraded by Radiometrics and reinstalled on the MWR, the air 
temperature sensor failed to properly report. It was determined that the wires carrying the 
signal to the analog board did not conform to the standard expected by the upgraded blower. 
The problem was corrected by modifying the MWR software to read the signal from the 
appropriate corresponding channel.

• tkair

SGP/MWR/E14 - computer problem

The computer was operating sporadically, requiring frequent reboots and resulting in 
periods of missing data. A warranty replacement of the motherboard corrected the problem.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• tknd
• bbn23
• 23.8 GHz sky brightness temperature(tbsky23)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• bb23
• wet_window
• tnd23
• Altitude above mean sea level(alt)
• Total water vapor along LOS path(vap)
• sky23
• tkair
• tc23
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• North latitude(lat)
• base_time
• bbn31
• East longitude(lon)
• tnd31
• tkbb
• bb31
• tnd_nom31
• tnd_nom23
• sky31
• time_offset
• tc31
• tkxc

SGP/MWR/B1 - 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.B1 20020412.1600.  The 
MONORTM-based retrieval coefficients became active at SGP.B1 20050624.2100.

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 water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)

SGP/MWR/B4 - 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.B4 20020415.2300.  The 
MONORTM-based retrieval coefficients became active at SGP.B4 20050624.2100.

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 water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)

SGP/MWR/B5 - 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.B5 
20020415.2300.  The MONORTM-based retrieval coefficients became active 
at SGP.B5 20050624.2100.

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 water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)

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 water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)

SGP/MWR/E14 - 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.E14 
20020416.0000.  The MONORTM-based retrieval coefficients became active 
at SGP.E14 20050628.2300.

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.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Total water vapor along LOS path(vap)

NSA/MWR/C1 - Reprocess: Revised Calibration 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 NSA.C1 
20020425.1900.  The MONORTM-based retrieval coefficients became active 
at NSA.C1 20050629.0000.

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 water vapor along LOS path(vap)
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)

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.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Total water vapor along LOS path(vap)

TWP/MWR/C1 - 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 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).

The Rosenkranz-based retrieval coefficients became active at TWP.C1 
20020504.0200.  The MONORTM-based retrieval coefficients became active 
at TWP.C1 20050630.2100.

Note: The TWP.C1 data for 19961011-20050630 have been reprocessed to apply the

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Total water vapor along LOS path(vap)

SGP/MWR/E14 - Reprocessed and Corrected:thermal instability

DATA REPROCESSED and CORRECTED: 

During periods of high ambient temperature, the instrument was thermally unstable. The 
problem was corrected by increasing the RF deck temperature from 50 to 56 C. The data were 
reprocessed with derived calibration coefficients after the reference temperature tkmx was 
adjusted.  

ORIGINAL DQR CATEGORY: Yellow( Suspect)

REPROCESSED and CORRECTED DATA ARCHIVED:2016-03-29

REPROCESS IDENTIFICATION NUMBER: RID 206

---------------------------------------------------
--- ORIGINAL DQR DESCRIPTION ---
---------------------------------------------------
During periods of high ambient temperature, the instrument may have been thermally 
unstable. The problem was corrected by increasing the RF deck temperature from 50 to 56 C.

The data will need to be reprocessed with calibration coefficients derived after the 
reference temperature, tkmx, was adjusted.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)
• Mean 31.4 GHz sky brightness temperature(tbsky31)

NSA/MWR/C2 - Thermally unstable

Between 08/12 and 08/17 the instrument displayed some intermittent thermal instability. 
Measurement accuracy may be degraded during these time periods.

Periods of thermal instability may be identified by checking the black body temperature 
Tkbb. If Tkbb > 303K (30 C) the instrument is unstable.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)

NSA/MWR/C2 - New software version (4.15) installed

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.

• sky23
• Temperature, brightness, longwave(ir_temp)
• tkxc
• tc31
• 23.8 GHz sky brightness temperature(tbsky23)
• Total water vapor along LOS path(vap)
• tkbb
• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• bbn31
• tknd
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• bbn23
• tc23
• tnd_nom23
• bb23
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• sky31
• bb31
• tnd31
• tnd23
• tnd_nom31
• tkair

SGP/MWR/E14 - New software version (4.15) installed

A problem began with the installation of MWR.EXE version 4.12 in May 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 8/1/2005. As a consequence of this 
upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s.

• Water, liquid, total along line-of-sight path, mean, 5-min avg(liq)
• bbn31
• tknd
• 23.8 GHz sky brightness temperature(tbsky23)
• bbn23
• tnd31
• bb23
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• tnd_nom31
• bb31
• tkbb
• tnd23
• tnd_nom23
• Total water vapor along LOS path(vap)
• sky23
• sky31
• tkair
• tc23
• tc31
• Sky/Cloud Infrared Temperature(sky_ir_temp)
• tkxc