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20000731: Unidata-Wisconsin datastream image compression change

>From: David Wojtowicz <address@hidden>
>Organization: University of Illinois
>Keywords: 200007311635.e6VGZfT07007 ldm-mcidas pnga2area headers


>Can you provide more specific information about the PNG imagery
>headers for the current products?

The header follows the form (included for completeness of the tracking system):

pnga2area  Qx pc anum SAT BAND RES CCYYMMDD HHMM
           ^  ^    ^   ^    ^   ^     ^      ^__ time in [HHMM]
           |  |    |   |    |   |     |_________ date in [CCYYMMDD]
           |  |    |   |    |   |_______________ image res info from SATBAND
           |  |    |   |    |___________________ image band info from SATBAND
           |  |    |   |________________________ satellite name from SATANNOT
           |  |    |____________________________ default output AREA number
           |  |_________________________________ McIDAS ROUTE.SYS product code
           |____________________________________ broadcast time designator

CIMSS products have been tagged with a broadcast time designator of
'Q0'.  The other currently available imagery in the broadcast is tagged
with 'Q1.  New imagery will be tagged according to their data
acquisition quartile.  For instance, if we double the VIS and IR
products, then the images taken from half past the hour to 45 minutes
past the hour will be tagged 'Q3'.

This scheme allows IDD leaf node sites to request just the images that
they want.  I recommend that leaf node sites that have successfully
transitioned to use of the PNG compressed imagery change what images
they request from their upstream site.  The following is an example of
requesting all MCIDAS feed, PNG compressed, CIMSS and H+0 - H+15 GOES
AREA products:

request MCIDAS "^pnga2area Q[01]" upstream_IDD_feed_machine_name

Of course, after making a change like this in ldmd.conf, your LDM has to
be stopped and restarted.

>such as what we should expect
>to see in the pc, anum, SAT, BAND, and RES fields.

pc   -> 2-character product code.  This is exactly the same as what is
        coming in as the first argument to the DIALPROD= sequence:

        Pcode   Product Description
        CA      CIMSS Cloud Top Pressure
        CB      CIMSS Precipitable Water
        CC      CIMSS Sea Surface Temperature
        CD      CIMSS Lifted Index
        CE      CIMSS CAPE
        CF      CIMSS Ozone
        UA      Educational floater I
        UB      GOES-West Western US Water Vapor
        UC      Educational floater II
        UI      GOES-East North America Infrared
        UV      GOES-East North America Visible
        UW      GOES-East North America Water Vapor
        UX      Global Mollweide Infrared Composite
        UY      Global Mollweide Water Vapor Composite
        U1      Antarctic composite
        U3      Manually Digitized Radar
        U5      GOES-West Western US Infrared
        U9      GOES-West Western US Visible

anum -> default AREA file number to be used IF one uses the decoder's
        '-d' and '-r' flags.  The default AREA file number will be overridden
        if one uses the McIDAS routing table, ROUTE.SYS, concepts.  The
        default AREA file numbers currently being sent are:

        Def. Anum(s)  Product Description
        1100          CIMSS Cloud Top Pressure
        1110          CIMSS Precipitable Water
        1120          CIMSS Sea Surface Temperature
        1130          CIMSS Lifted Index
        1140          CIMSS CAPE
        1150          CIMSS Ozone
         160  163     Educational floater I
         170  173     GOES-West Western US Water Vapor
          60   63     Educational floater II
         150  153     GOES-East North America Infrared
         140  143     GOES-East North America Visible
         210  213     GOES-East North America Water Vapor
         100  103     Global Mollweide Infrared Composite
         110  113     Global Mollweide Water Vapor Composite
         190  193     Antarctic composite
         200  205     Manually Digitized Radar
         130  133     GOES-West Western US Infrared
         120  123     GOES-West Western US Visible

SAT  -> value of SAT for various platforms

        String       Satellite Platform
        GOES-10_IMG  GOES West imager bands
        GOES-10_SND  GOES West sounder bands
        GOES-8_IMG   GOES East imager bands
        GOES-8_SND   GOES East sounder bands
        METEOSAT6    METEOSAT 6 bands
        UNKSAT       Unknown satellite (e.g., for products)

BAND -> values of BANDS for currently broadcast imagery:

        String       Satellite Platform
         3.9um        3.9 um infrared
         6.8um        6.8 um infrared (GEMPAK typically refers to this as WV)
        10.7um       10.7 um infrared (GEMPAK typically refers to this as IR)
        12.0um       12.0 um infrared
         0.65um       0.65 um visible (GEMPAK typically refers to this as VIS)
        UNKBAND      unknown band

RES  -> values of RES for currently broadcast imagery:

        String       Satellite Platform
        1km          1 km (e.g., 0.65 um visible (VIS))
        2km          2 km (e.g., 2x blow down 0.65 um visible (VIS))
        4km          4 km (e.g., 10.7 um infrared (IR))
        8km          8 km (e.g., 6.8 um infrared (Water Vapor))

>The example pqact.conf entries in the ldm-mcidas-pqact.conf file
>only refer to the CIMSS products.  Example entries for
>the imagery would be helpful.

The information for SAT, BAND, and RES is taken from the files SATANNOT
and SATBAND that are included in the ldm-mcidas (and McIDAS)
distribution(s).  You can peruse this file to get an idea of what kinds
of names are possible (there are too many combinations to present

Please let me know if you need more information.

Tom Yoksas

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