Data Quality Reports for Session: 149847 User: shannon1t1 Completed: 05/01/2013


TABLE OF CONTENTS

DQR IDSubjectData Streams Affected
D050725.9TWP/MWR/C1 - Reprocessed: Revised Retrieval Coefficientstwp5mwravgC1.c1, twpmwrlosC1.b1, twpmwrtipC1.a1


DQRID : D050725.9
Start DateStart TimeEnd DateEnd Time
05/04/2002020006/30/20052100
Subject:
TWP/MWR/C1 - Reprocessed: Revised Retrieval Coefficients
DataStreams:twp5mwravgC1.c1, twpmwrlosC1.b1, twpmwrtipC1.a1
Description:
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
Measurements:twp5mwravgC1.c1:
  • Total liquid water along LOS path(liq)
  • Total water vapor along LOS path(vap)

twpmwrtipC1.a1:
  • liqtip
  • vaptip

twpmwrlosC1.b1:
  • Total liquid water along LOS path(liq)
  • Total water vapor along LOS path(vap)


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