Data Quality Reports for Session: 106402 User: sluchs Completed: 07/06/2007


TABLE OF CONTENTS

DQR IDSubjectData Streams Affected
D050725.4SGP/MWR/B5 - Reprocess: Revised Retrieval CoefficientssgpmwrlosB5.a1, sgpmwrlosB5.b1, sgpmwrtipB5.a1, sgp5mwravgB5.c1, sgpqmemwrcolB5.c1
D050812.4SGP/THWAPS/B5 - Minor biases in humidity and saturation vapor pressuresgpthwapsB5.b1
D050927.4SGP/MWR/B5 - New software version (4.15) installedsgpmwrlosB5.b1, sgpmwrtipB5.a1


DQRID : D050725.4
Start DateStart TimeEnd DateEnd Time
04/15/2002230006/24/20052100
Subject:
SGP/MWR/B5 - Reprocess: Revised Retrieval Coefficients
DataStreams:sgpmwrlosB5.a1, sgpmwrlosB5.b1, sgpmwrtipB5.a1, sgp5mwravgB5.c1, sgpqmemwrcolB5.c1
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).

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.
Measurements:sgpmwrlosB5.a1:
  • Mean total water vapor amount along LOS path(vap)
  • Mean total liquid water amount along LOS path(liq)

sgpmwrtipB5.a1:
  • Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
  • Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)

sgpqmemwrcolB5.c1:
  • Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)
  • Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)

sgp5mwravgB5.c1:
  • Mean total water vapor amount along LOS path(vap)
  • Mean total liquid water amount along LOS path(liq)

sgpmwrlosB5.b1:
  • Mean total liquid water amount along LOS path(liq)
  • Mean total water vapor amount along LOS path(vap)


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DQRID : D050812.4
Start DateStart TimeEnd DateEnd Time
09/21/1999000007/31/20051714
Subject:
SGP/THWAPS/B5 - Minor biases in humidity and saturation vapor pressure
DataStreams:sgpthwapsB5.b1
Description:
The THWAPS humidity sensor output was scaled so that the instrument output
voltage range (0-1VDC) represented 0-100 %RH. Comparisons with the
co-located chilled mirror sensor at the CF suggested that the THWAPS RH
sensor was reading artifically low at high humidities because of this 100
%RH maximum. 
   
The scaling of the system was changed so that 0-1 VDC now represents 0-110
%RH. This resulted in a slight loss of precision in the measurements, but
since the RH measurement is only accurate to 2-3 %RH at best, this isn't a
significant problem.
   
The saturation vapor correction when temps are below 0C contained an error
in the multiplier.  The incorrect multiplier only equates to an error of
0.01 kPa which is less than the stated uncertainty of the measurement (+/-
0.035 kPa).
Measurements:sgpthwapsB5.b1:
  • Vapor Pressure (kiloPascals)(vap_pres)
  • Relative humidity scaled, by total column amount from MWR(rh)


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DQRID : D050927.4
Start DateStart TimeEnd DateEnd Time
07/10/2002170009/13/20052124
Subject:
SGP/MWR/B5 - New software version (4.15) installed
DataStreams:sgpmwrlosB5.b1, sgpmwrtipB5.a1
Description:
A problem began with the installation of MWR.EXE version 4.12 in July 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 9/13/2005. As a consequence of this 
upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s.
Measurements:sgpmwrtipB5.a1:
  • Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
  • 31.4 GHz sky signal(tipsky31)
  • Blackbody kinetic temperature(tkbb)
  • Noise diode mount temperature(tknd)
  • Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
  • 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
  • 31.4 GHz goodness-of-fit coefficient(r31)
  • 23.8 GHz blackbody+noise injection signal(bbn23)
  • Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
  • Temperature correction coefficient at 23.8 GHz(tc23)
  • 23.8 GHz Blackbody signal(bb23)
  • Temperature correction coefficient at 31.4 GHz(tc31)
  • 31.4 GHz Blackbody signal(bb31)
  • Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
  • Mixer kinetic (physical) temperature(tkxc)
  • Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
  • Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
  • Ambient temperature(tkair)
  • 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
  • 23.8 GHz sky signal(tipsky23)
  • Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
  • 23.8 GHz goodness-of-fit coefficient(r23)
  • 31.4 GHz blackbody+noise injection signal(bbn31)
  • Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)

sgpmwrlosB5.b1:
  • Mixer kinetic (physical) temperature(tkxc)
  • Ambient temperature(tkair)
  • Temperature correction coefficient at 31.4 GHz(tc31)
  • 23.8 GHz sky signal(sky23)
  • Blackbody kinetic temperature(tkbb)
  • Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
  • 31.4 GHz Blackbody signal(bb31)
  • Mean total water vapor amount along LOS path(vap)
  • Noise diode mount temperature(tknd)
  • Mean IR brightness temperature(ir_temp)
  • Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
  • 31.4 GHz blackbody+noise injection signal(bbn31)
  • Mean 31.4 GHz sky brightness temperature(tbsky31)
  • Mean total liquid water amount along LOS path(liq)
  • 23.8 GHz blackbody+noise injection signal(bbn23)
  • 31.4 GHz sky signal(sky31)
  • Mean 23.8 GHz sky brightness temperature(tbsky23)
  • Sky/Cloud Infra-Red Temperature(sky_ir_temp)
  • Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
  • 23.8 GHz Blackbody signal(bb23)
  • Temperature correction coefficient at 23.8 GHz(tc23)
  • Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)


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