TWP/MWR/C2 - Heater problem

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

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

• Fraction of data in averaging interval with water on the Teflon window(water_flag_fraction)

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

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 total water vapor amount along LOS path(vap)
• Mean total liquid water amount 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)

• Mean total liquid water amount along LOS path(liq)
• Mean total water vapor amount along LOS path(vap)

TWP/MWR/C2 - Missing data

The heater blower assembly was causing the fuse to blow.  The instrument was taken offline 
until a replacement arrives.

• 31.4 GHz sky signal(sky31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Blackbody kinetic temperature(tkbb)
• north latitude for all the input platforms.(lat)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Mean 23.8 GHz sky brightness temperature(tbsky23)
• 31.4 GHz Blackbody signal(bb31)
• Mean total water vapor amount along LOS path(vap)
• 23.8 GHz sky signal(sky23)
• Ambient temperature(tkair)
• Mean IR brightness temperature(ir_temp)
• Time offset from base_time(base_time)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz blackbody+noise injection signal(bbn31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• Mean total liquid water amount along LOS path(liq)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• east longitude for all the input platforms.(lon)
• 23.8 GHz Blackbody signal(bb23)
• Noise diode mount temperature(tknd)
• Actual Azimuth(actaz)
• Time offset of tweaks from base_time(time_offset)
• Actual elevation angle(actel)
• altitude above sea levelaltunits(alt)
• Sky/Cloud Infra-Red Temperature(sky_ir_temp)
• Temperature correction coefficient at 31.4 GHz(tc31)

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

• north latitude for all the input platforms.(lat)
• Standard deviation about the mean for the total water vapor amount(vap_sdev)
• east longitude for all the input platforms.(lon)
• Fraction of data in averaging interval with water on the Teflon window(water_flag_fraction)
• Mean total liquid water amount along LOS path(liq)
• Standard deviation about the mean for the 31.4 GHz sky brightness temperature(tbsky31_sdev)
• Mean IR brightness temperature(ir_temp)
• Time offset of tweaks from base_time(time_offset)
• Number of points included in the ensemble of all the fields except the ir_temp
  fields(num_obs)
• Standard deviation about the mean for the 23.8 GHz sky brightness temperature(tbsky23_sdev)
• altitude above sea levelaltunits(alt)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• Number of points included in the ir_temp ensemble(num_obs_irt)
• Time offset from base_time(base_time)
• Standard deviation about the mean for the IR brightness temperature(ir_temp_sdev)
• Mean 23.8 GHz sky brightness temperature(tbsky23)
• Mean total water vapor amount along LOS path(vap)
• Standard deviation about the mean for the total liquid water amount(liq_sdev)

• 31.4 GHz sky signal(tipsky31)
• north latitude for all the input platforms.(lat)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 31.4 GHz goodness-of-fit coefficient(r31)
• Actual Azimuth(actaz)
• 23.8 GHz sky signal(tipsky23)
• 31.4 GHz blackbody+noise injection signal(bbn31)
• 31.4 GHz Blackbody signal(bb31)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Ambient temperature(tkair)
• altitude above sea levelaltunits(alt)
• Noise diode mount temperature(tknd)
• Time offset from base_time(base_time)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Time offset of tweaks from base_time(time_offset)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Actual elevation angle(actel)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz Blackbody signal(bb23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• east longitude for all the input platforms.(lon)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Mixer kinetic (physical) temperature(tkxc)