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Home > Products > Operational upgrades > Enhanced tropical cyclone trajectory forecast products >     
   

Enhanced tropical cyclone trajectory forecast products


 

 
 

ECMWF is enhancing its tropical cyclone trajectory (TC track) forecast products.

The switch from the current to the new products will be implemented for the 12 UTC run on 1 December 2013. This long period was chosen so as not to interfere with the operational use of the data during the ongoing tropical cyclone season. Test data will be available via the ECMWF ftp data portal and ecPds dissemination from now until the implementation date. On the implementation date the new products will replace the current products on all dissemination systems (GTS, DCPC, ftp data portal, ecPds).

On the day of implementation, the encoding of TC track products will change from WMO FM 94-IX Ext. BUFR edition 3 (BUFR-3) to WMO FM 94-IX Ext. BUFR edition 4 (BUFR-4) and missing value indicators will be used to describe unavailable data entries.

The way to request these products will not change. Also any file names and GTS headers will remain unaffected.

Information on the near-real-time availability of these products can be found at:

For further information and advice regarding the upgrade, or to report any problems with the new products, please contact User Support .


Background

ECMWF's TC track products contain time, position (latitude/longitude in degrees), central pressure (hPa) and location and intensity of maximum wind speed (m/s) for each tropical cyclone identified and tracked in the forecast. They are produced only for tropical cyclones where an observation report is present at the analysis time.

Enhancements

ECMWF is implementing a new tracker software which is described in the ECMWF Newsletter No. 130 (pp17-23 - Winter 2011/12). The new TC tracks are produced for forecasts up to 240 hours (previously to 120 hours), or until the tropical cyclone dissipates if earlier. The tracker software is applied to forecast output every 6 hours (previously every 12 hours) and the algorithm allows a tropical cyclone to be absent for 24 hours and then re-appear.

Technical characteristics

The enhanced TC tracks are coded in BUFR-4 and will replace the current BUFR-3 products. The BUFR templates will remain unchanged but missing value indicators will be used to describe unavailable data entries.

Differences between the old and new BUFR format

  • BUFR Section 1 changes:
    • edition number changes from 3 to 4;
    • length of section 1 changes from 18 bytes to 22 bytes.
  • Some steps are coded as missing values in the new product.
  • BUFR tables version 16 (files B0000000000000016000.TXT,D0000000000000016000.TXT and C0000000000000016000.TXT).are needed to successfully decode the new TC track products. Users that do not have these tables can find them in the latest version of ECMWF's BUFR decoding software (BUFRDC).

TC track products in dissemination

New TC track products in BUFR-4 are available to users of ECMWF dissemination products at their designated ECPDS dissemination destinations using the same dissemination file names as BUFR-3 products but with EXPVER=59. Files are in 'standby mode' so users can retrieve them for testing at their convenience.

TC track products on ftp data portal for WMO

TC track products in BUFR-4 are available on the ECMWF ftp data portal in the directory named test (for login details see here). Test products are provided from both the high-resolution forecast (HRES) and the ensemble forecast (ENS). For comparison, the current TC track products in BUFR-3 are available from the usual location on the ECMWF ftp data portal. Users are encouraged to use BUFR-4 products as they will fully replace those in BUFR-3. Note that products are available only when tropical cyclones have been identified and tracked in the forecast.

TC track products archived in MARS

For compatibility reasons, TC track products archived in MARS will continue to be encoded in BUFR-3 but will include all enhancements described above.

Tropical cyclone products on the Web

The corresponding web charts - see ECMWF Newsletter No. 130 (pp17-23 - Winter 2011/12) - will also be enhanced on the date of implementation. These products can be accessed at:

Document versions

Date
Changes
25.07.2013 Initial version

 

Top of page 30.07.2013
 
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