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NOAA’s National Weather Service NDFD Dissemination Services

NOAA’s National Weather Service NDFD Dissemination Services. Allan Darling Office of the CIO, Telecommunication Operations Center National Digital Forecast Database Technical Workshop August 13, 2003. NDFD Dissemination Services. What will we cover? Where to find NDFD product files

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NOAA’s National Weather Service NDFD Dissemination Services

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  1. NOAA’sNational Weather ServiceNDFD Dissemination Services Allan Darling Office of the CIO, Telecommunication Operations Center National Digital Forecast Database Technical Workshop August 13, 2003

  2. NDFD Dissemination Services • What will we cover? • Where to find NDFD product files • Information about the servers where the data is stored • How files are named • How files are constructed • How product headings are formed • What a “super heading” is • Where to go for more information

  3. NDFD Dissemination Services • Where to find NDFD product files – • Files are available via: • ftp://tgftp.nws.noaa.gov • http://weather.noaa.gov/pub • ftp://ptgftp.nws.noaa.gov • (Access to ptgftp.nws.noaa.gov is limited to SAS customers - see http://weather.gov/datamgmt/fos/fospage.html for more information about Server Access Services.

  4. NDFD Dissemination Services • About the servers – • All servers are classed a operational systems with 24x7 support and monitoring • tgftp.nws.noaa.gov – Cluster of five public anonymous FTP servers • weather.noaa.gov – Cluster of five public HTTP servers • ptgftp.nws.noaa.gov – Cluster of two restricted access anonymous FTP servers

  5. NDFD Dissemination Services • Where to find NDFD product files – • On each server, NDFD data is found under the path: • /SL.us008001/ST.expr/DF.gr2/DC.ndfd/... • The path indicates that the data is on the public NWSTG FTP server, is experimental, is encoded in WMO GRIB Edition 2 format, and is all related to the NDFD data category. • See http://www.nws.noaa.gov/datamgmt/filstnd.html for more information about the directory and file naming standards used on the NWSTG FTP and HTTP Servers

  6. NDFD Dissemination Services • How files are named – • Following the data format and category directories, the last directory and the file name specify: • the geographic area (/AR.aaaaaaaa) • the data subcategory (/ds.sssss) • A list of all the NDFD Sectors (geographic areas) and the data subcategories is available at http://www.nws.noaa.gov/datamgmt/doc/ndfdelem.xls This spreadsheet also defines the NDFD sectors by Lat/Lon and grid points

  7. NDFD Dissemination Services • How files are named – • The file • ftp://tgftp.nws.noaa.gov/SL.us008001/ST.expr/DF.gr2/DC.ndfd/AR.midatlan/ds.maxt.bin • contains the daytime maximum temperature for the Mid-Atlantic sector.

  8. NDFD Dissemination Services • How files are constructed – • Files are comprised of: • A flag field separator block (option 2) • A super heading • One or more GRIB products each comprised of • A flag field separator block (option 2) • A WMO Heading • A GRIB product

  9. NDFD Dissemination Services • How files are constructed – • A flag field separator block (option 2) is a file delimiter that provides the length of the product that follows it. The format is: • ****nnnnnnnnnn****lf • Where nnnnnnnnnn is the length of the product following the seperator, in bytes and lf is an ASCII line feed. See http://weather.gov/tg/fstandrd.html for more details.

  10. NDFD Dissemination Services • How files are constructed – • ****0000149136**** • YGCZ99 KWBN 031906 • ****0000018449**** • YGCB00 KWBN 031906 • GRIB..................7777 • ****0000018847**** • YGCC00 KWBN 031906 • GRIB.....................7777 • . • . • . • ****0000018051**** • YGCI00 KWBN 031906 • GRIB.................7777

  11. NDFD Dissemination Services • How product headings are formed – • Generic WMO Heading: T1T2A1A2ii CCCC • Generic NDFD Heading: YT2A1A2ii KWBN • T2 specified the data type (data subcategory) • A1 specifies the geographic designator (NDFD sector) • A2 and ii together specify the NDFD reference time (not represented in the directory or file names)

  12. NDFD Dissemination Services • How product headings are formed – • Generic NDFD Heading: YT2A1A2ii KWBN • The possible values for T2 , A1 , A2 , and ii and their meanings are specified on the NDFD WMO Heading Reference page at • http://weather.gov/datamgmt/doc/ndfdref.html

  13. A = SKY COVER B = WIND DIRECTION C = WIND SPEED D = PROBABILITY OF PRECIPITATION (12 HOURS) E = SURFACE TEMPERATURE F = DEWPOINT TEMPERATURE G = DAYTIME MAXIMUM TEMPERATURE H = NIGHTTIME MINIMUM TEMPERATURE I = QUANTITATIVE PRECIPITATION J = WEATHER K = WAVE HEIGHT S = SNOWFALL AMOUNT U = FREE AIR WIND DIRECTION V = FREE AIR WIND SPEED NDFD Dissemination Services How product headings are formed – T2 – data type

  14. ****0000149136**** YGCZ99 KWBN 031906 ****0000018449**** YGCB00 KWBN 031906 GRIB..................7777 ****0000018847**** YGCC00 KWBN 031906 GRIB.....................7777 . . . ****0000018051**** YGCI00 KWBN 031906 GRIB.................7777 YGCB00 KWBN Y -NDFD Product G – Daytime Maximum Temperature C – Mid-Atlantic Sector B – Day 1 00 – Hour 0 NDFD Dissemination Services Decoding a product heading -

  15. NDFD Dissemination Services • What is a “super heading”? • In order to aggregate all of the forecast periods for one data subcategory and one sector, the “super heading” was developed. • The super heading specifies the data subcategory in T2 and the geographic sector in A1. A2 and ii are fixed as “Z99”: • NDFD Super Heading: YT2A1Z99KWBN

  16. ****0000149136**** YGCZ99 KWBN 031906 ****0000018449**** YGCB00 KWBN 031906 GRIB..................7777 ****0000018847**** YGCC00 KWBN 031906 GRIB.....................7777 . . . ****0000018051**** YGCI00 KWBN 031906 GRIB.................7777 YGCZ99 KWBN Y -NDFD Product G – Daytime Maximum Temperature C – Mid-Atlantic Sector Z99 – Super Heading The super heading contains one or more instances of a flag field separator, WMO heading and GRIB product. NDFD Dissemination Services What is a “super heading”?

  17. ****0000149136**** YGCZ99 KWBN 031906 ****0000018449**** YGCB00 KWBN 031906 GRIB..................7777 ****0000018847**** YGCC00 KWBN 031906 GRIB.....................7777 . . . ****0000018051**** YGCI00 KWBN 031906 GRIB.................7777 ****0000149136**** YGCZ99 KWBN 031906 149136 is the length, in bytes, of the super heading and all the following groups of flag field separators, WMO headings, and GRIB products. NDFD Dissemination Services Super heading flag field separator -

  18. ****0000149136**** YGCZ99 KWBN 031906 ****0000018449**** YGCB00 KWBN 031906 GRIB..................7777 ****0000018847**** YGCC00 KWBN 031906 GRIB.....................7777 . . . ****0000018051**** YGCI00 KWBN 031906 GRIB.................7777 ****0000018449**** YGCB00 KWBN 031906 GRIB.............7777 18449 is the length, in bytes, of the single heading and GRIB product. NDFD Dissemination Services “Regular” flag field separator -

  19. NDFD Dissemination Services • For more dissemination information – • NWSTG Data Management NDFD Reference - http://weather.gov/datamgmt/doc/ndfdindex.html • Directory and File Naming Standards – • http://weather.gov/datamgmt/filstnd.html • Family of Services Main Page – • http://weather.gov/datamgmt/fos/fosindex.html • Gateway File Standards and Content Structures – • http://weather.gov/tg/fstandrd.html

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