SGP/MWR/C1 - Instrument problem

The MWR mixer temperature, blackbody temperature, and moisture flag are incorrect. This 
began when the instrument was returned to service after the analog board was temporarily 
removed to check the presence and absence of certain resistors. The board must have been 
accidently damaged during this process.

• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• (tknd)
• Blackbody kinetic temperature(tkbb)
• Mixer kinetic (physical) temperature(tkxc)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Ambient temperature(tkair)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)

• (tknd)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Blackbody kinetic temperature(tkbb)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Ambient temperature(tkair)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)

• Mixer kinetic (physical) temperature(tkxc)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Blackbody kinetic temperature(tkbb)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Ambient temperature(tkair)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• (tknd)

SGP/MWR/C1 - thermal instability

The analog board was replaced with a spare (D041001.3) with a reference temperature that 
was set too low (306 K) so that during periods of high ambient temperature, the instrument 
became thermally unstable. The problem was corrected when the temperature setting was 
increased (to 311 K).

• 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(tbsky23tip)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)

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

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

SGP/MWR/C1 - 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 CF1 were applied when 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)

• 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)

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

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

SGP/MWR/C1 - 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 as follows (BCR 456):
SGP/C1 (Lamont)     4/16/2002, 2000
SGP/B1 (Hillsboro)  4/12/2002, 1600
SGP/B4 (Vici)       4/15/2002, 2300
SGP/B5 (Morris)     4/15/2002, 2300
SGP/B6 (Purcell)    4/16/2002, 2200
SGP/E14(Lamont)     4/16/2002, 0000
NSA/C1 (Barrow)     4/25/2002, 1900 
NSA/C2 (Atqasuk)    4/18/2002, 1700
TWP/C1 (Manus)      5/04/2002, 0200
TWP/C2 (Nauru)      4/27/2002, 0600
TWP/C3 (Darwin)     inception

The MONORTM-based retrieval coefficients became active as follows (BCR 984):

SGP/C1 (Lamont)     6/28/2005, 2300
SGP/B1 (Hillsboro)  6/24/2005, 2100
SGP/B4 (Vici)       6/24/2005, 2100
SGP/B5 (Morris)     6/24/2005, 2100
SGP/B6 (Purcell)    6/24/2005, 1942
SGP/E14(Lamont)     6/28/2005, 2300
NSA/C1 (Barrow)     6/29/2005, 0000 
NSA/C2 (Atqasuk)    6/29/2005, 0000
TWP/C1 (Manus)      6/30/2005, 2100
TWP/C2 (Nauru)      6/30/2005, 2100
TWP/C3 (Darwin)     6/30/2005, 2100
PYE/M1 (Pt. Reyes)  4/08/2005, 1900**

** At Pt. Reyes, the original retrieval coefficients implemented in March 2005 were based 
on a version of the Rosenkranz model that had been modified to use the HITRAN half-width 
at 22 GHz and to be consistent with the water vapor continuum in MONORTM.  These 
retrievals yield nearly identical results to the MONORTM retrievals.  Therefore the Pt. Reyes 
data prior to 4/08/2005 may not require reprocessing.

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

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

• 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)

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

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

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