Using CSPP QuickLooks and Direct Broadcast data to view gridded NUCAPS fields
NOAA-20 852-mb Temperatures, ca. 1750 UTC on 7 August 2020. Inset: Global Map of where the data sit (Click to enlarge)
A previous blog post (link) detailed how to access NOAA CLASS to create Gridded NUCAPS (NOAA-Unique Combined Atmospheric Processing System) imagery from those data. (You can also view some gridded NUCAPS fields here; click here to see the 850-mb field of Temperature from that site, it is very similar to the imagery above). This post details how to use the CSPP QuickLooks software package to create imagery at different levels. These QuickLook fields give good information quickly and at many different levels for Direct Broadcast data.
Download the Sounder QuickLook software for Linux from the CIMSS website here. Documentation is also available at the download website. The files to download are shown in this graphic. The package is self-contained and requires only unzipping and un-tarring.
After downloading, define the $CSPP_SOUNDER_QL_HOME variable as the directory where the package sits on your unix platform. Then, set up the environment with the command: source $CSPP_SOUNDER_QL_HOME/cspp_sounder_ql_env.sh.
This software package works on NUCAPS EDR (Environmental Data Records) files created at Direct Broadcast sites by CSPP (that are also available after some time from CLASS), and those files can be found at websites such as this one: ftp://ftp.ssec.wisc.edu/pub/eosdb/ — underneath this are directories for NOAA-20 (‘j01’) and Suomi-NPP (‘npp’). For example, NOAA-20 data from 7 August 2020 from the ~1747 UTC overpass is at ftp://ftp.ssec.wisc.edu/pub/eosdb/j01/crisfsr/2020_08_07_220_1747/ (This website is not preserved forever but will go away after about a week. The directory includes an edr subdirectory that contains the files needed; a typical filename looks like this: NUCAPS-EDR_v2r0_j01_s202008071752319_e202008071753017_c202008071830250.nc; it is the EDR for NOAA-20 and it contains data on 7 August 2020 from 1752 through 1753 UTC. The directory will include up to about 18 of these EDRs (the number depends on how long the satellite is within view of the Direct Broadcast antenna at CIMSS).
How do you create the QuickLooks?
- Move the EDR files to your machine, and that’s easily done with
wget ftp://ftp.ssec.wisc.edu/pub/eosdb/j01/crisfsr/2020_08_07_220_1747/edr/NUCAPS-EDR*. Of course, the yyyy_mm_dd_jdy_hhmm value (2020_08_07_220_1747 above) changes with each satellite overpass! - Create a list of the files in that directory, i.e.,
files=$CSPP_SOUNDER_QL_HOME/data/NUCAPS-EDR* - Invoke the shell script from
$CSPP_SOUNDER_QL_HOME/scripts/ql_level2_image.sh "$files" NUCAPS --dset temp --pressure 850. This will create an image, shown above, that is a temperature mapping at the closest pressure level to 850 mb in the NUCAPS retrieval. (Pressure levels in the Radiative Transfer Model that is used by NUCAPS are listed here; in the map label above, note that values are truncated, not rounded). You can also map dewpoint temperature (dwpt), relative humidity (relh) and mixing ratio (wmix). By default, temperature scaling matches the bounds of the image, but you can specify the bounds if needed, using--plotMin=250.0 --plotMax=300.0, for example. The time of the image is the time of the first scan line — for this ascending pass, it’s the southernmost line. In this QuickLook image, the airmass difference between the relatively cool air over Ohio/Indiana and the warmer air to the south is apparent.
You can also create a QuickLook SkewT/logP plots for each scan. This produces one SkewT per ScanLine, at the mid-point along the scanline that contains 30 separate profiles. The sounding below was produced by this command:
./ql_level2_skewt.sh ./data/NUCAPS-EDR_v2r0_j01_s202008071755119_e202008071755417_c202008071831450.nc NUCAPS
NOAA-20 NUCAPS Sounding from 1755 UTC on 7 August 2020 at 41.93º N, 75.81º W (Click to enlarge)
The SkewT has characteristics that suggest the presence of clouds. What did this particular sounding look like in AWIPS? That’s shown below. In AWIPS, the sounding also terminated at about 550 mb, and the temperature and dewpoint lines above that level match the Quick Look sounding shown above.
NSharp AWIPS presentation of NOAA-20 NUCAPS Sounding at 41.93 N, 75.81 W at ~17UTC on 7 August 2020 (Click to enlarge)
NUCAPS Sounding Availability points from this NOAA-20 pass are shown below. The sounding point — in yellow — that is circled in blue is the one shown above. The sounding just to the east of that point — a green point that gives useful information down into the boundary layer — is shown here. Quick Looks choose the mid-point sounding along the line, and sometimes, as in this case, the retrieval that produced the profile did not converge.
NOAA-20 NUCAPS Sounding Availability Points from AWIPS, 1732 UTC on 7 August 2020 (Click to enlarge). The sounding shown above is from the point circled in blue. This is in the middle of the 30 sounding points along the horizontal line of available profiles.