Table of Contents:

SSMIS Data Processing

Step 1: obtain SSMIS data from AFWA

AFWA-provided SSMIS data are archived on MSS under
mss:/LIUZ/radiances_afwa/SSMIS_July07_NCEPBUFR
mss:/LIUZ/radiances_afwa/SSMIS_Aug07_NCEPBUFR
mss:/LIUZ/radiances_afwa/SSMIS_Sep07_NCEPBUFR

AFWA-provided SSMIS data are in the form of one-orbit per file,
for example,
tdris_f16_d20070801_s012545_e031834_r19528_cfnoc.bufr
tdris_f16_d20070801_s031400_e045000_r19529_cfnoc.bufr
tdris_f16_d20070801_s062800_e083700_r19531_cfnoc.bufr
tdris_f16_d20070801_s083300_e101900_r19532_cfnoc.bufr

s083300 - start_time 08h:33m:00s
e101900 - end_time 10h:19m:00s
r19532 - orbit number 19532

problems with the data

  • missing and duplicated rev numbers, for example,
    tdris_f16_d20070723_s013906_e033154_r19401_cfnoc.bufr
    tdris_f16_d20070723_s021200_e033200_r19401_cfnoc.bufr

Explanations provided by AFWA contractor Steve Swadley

Yes, there are occasional missing and duplicate revs in the data stream.
I cannot do anything about the missing revs.

However, for the duplicate revs, there are typically two one of two
reasons for this.

1)  A partial rev is processed at FNMOC , and the complete rev shows up
at FNMOC later from AFWA. If my memory serves me correctly, the AFWA
revs have 00 in the seconds field of the start and end rev times.  FNMOC
has the seconds included in the field, For example duplicate rev #
19362,  filenames are:
tdris_f16_d20070720_s072028_e092842_r19362_cfnoc.bufr and
tdris_f16_d20070720_s072800_e092800_r19362_cfnoc.bufr.

2)  A simple retransmit of the FNMOC rev  when the complete rev arrives.

Jeff Tesmer (FNMOC) and I have gone back and forth on this issue, as it
used to cause my radiance monitoring scripts to crash when duplicate
revs were found. Since I was running in a post-processing mode, I didn't
want to deal with duplicate revs, but...

There are easy ways to handle the duplicate revs. 
1)     Just choose the LARGER file and run with that filename.
2)    I have an IDL script that removes the SMALLER of the two files,
and I run that daily. For your case you would just need to run it once.
  • different rev numbers with over lapping times, for exmaple,
    tdris_f16_d20070811_s131300_e145800_r19677_cfnoc.bufr
    tdris_f16_d20070811_s131301_e145837_r19676_cfnoc.bufr

Explanations provided by AFWA contractor Steve Swadley

The AFWA and FNMOC rev numbers are off by one. Both centers claim they are correct.
FNMOC rev numbers agree with the number in the RDR file and NORAD elements.
Occasionally when an AFWA reship occurs, the FNMOC software doesn't do the rename properly.

There is also an issue when the day crossover occurs, which has plagued us from day one.
FNMOC gives a rev the day corresponding to the start time of the orbit.
AFWA gives a rev the day corresponding to the end time of the orbit,
even if 99% of the rev occurred in the previous day.

Step 2: Concatenate orbit-by-orbit files into 6-hourly files

The start_time/end_time in the filename are used for grouping data together into 6-hourly files.
However, the start_time/end_time in the filename are not the same as the time info found in the file content.
(Not much difference though. Just a few minutes.)

Step 3: Remove duplicated data and keep data in user-specified region

hclin-developed rw_rad_bufr_undup utility (with some codes borrowed from NCEP's dupsat utility (source code available from http://www.nco.ncep.noaa.gov/pmb/codes/nwprod/sorc/bufr_dupsat.fd/)) is used to remove duplicated data and keep data in user-specified region.

Step 4: plotting

hclin-developed rw_rad_bufr_undup utility is used to convert BUFR data into NetCDF format and a NCL script is written for plotting.

SSMIS coverage on t8_15km_2008 domain








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