TWP/MWR/C2 - Heater problem

When the wiring of the air temperature sensor was checked the heater apparently began 
activating too often.

• wet_window

• water_flag_fraction

• wet_window

TWP/MWR/C2 - mixer temperature

When the wiring of the air temperature sensor was checked the mixer temperature 
unexpectedly decreased 4 degrees. It increased to its normal value when the dielectric window was 
replaced. The problem was probably caused by a loose and/or corroded connection.

• tkxc

• tkxc

TWP/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 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.C2 20020427.0600.  The 
MONORTM-based retrieval coefficients became active at TWP.C2 20050630.2100.

Note: The TWP.C2 data for 19981028-20050630 have been reprocessed to apply the 
MONORTM-based retrievals for all time.  The reprocessed data were archived 20061003.

• mean_vap_mwr
• mean_liq_mwr

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

TWP/SONDE/C2 - Bad RH sensor

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below -50 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Humidity, relative(rh)
• Dewpoint Temperature(dp)

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

A problem began with the installation of MWR.EXE version 4.12 in November 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.

• tipsky23
• bbn31
• tkair
• tkbb
• tnd_nom31
• tkxc
• tnd31
• bbn23
• tc31
• r23
• tknd
• tnd23I
• bb31
• tc23
• tnd_nom23
• tnd23
• tnd31I
• r31
• tipsky31

• tnd_nom23
• IR Brightness Temperature(sky_ir_temp)
• tnd23
• sky23
• Total liquid water along LOS path(liq)
• bbn23
• bb31
• Temperature, brightness, longwave(ir_temp)
• tkbb
• tc23
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• 31.4 GHz sky brightness temperature(tbsky31)
• sky31
• tnd_nom31
• tkxc
• tkair
• Total water vapor along LOS path(vap)
• tknd
• tnd31
• bb23
• bbn31
• tc31

TWP/SONDE/C2 - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Humidity, relative(rh)
• Dewpoint Temperature(dp)
• Dry Bulb Temperature(tdry)

TWP/SONDE/C2  - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Humidity, relative(rh)
• Dewpoint Temperature(dp)
• Dry Bulb Temperature(tdry)

TWP/MWR/C2 - Missing Data

Data are missing and unrecoverable.

• tnd_nom23
• IR Brightness Temperature(sky_ir_temp)
• tnd23
• lat
• sky23
• Total liquid water along LOS path(liq)
• lon
• bbn23
• time_offset
• bb31
• Temperature, brightness, longwave(ir_temp)
• actel
• wet_window
• tkbb
• tc23
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• sky31
• 31.4 GHz sky brightness temperature(tbsky31)
• tnd_nom31
• tkxc
• tkair
• tknd
• Total water vapor along LOS path(vap)
• bb23
• tnd31
• bbn31
• alt
• tc31
• actaz
• base_time