ds083.3: GDAS/FNL 0.25 degree global grids

April 14, 2016
Posted by: RDA Team

Note: This page was originally sourced from our Blogger page: http://ncarrda.blogspot.com/2016/03/ds0833-gdasfnl-025-degree-global-grids.html

Since July 8, 2015, RDA has been archiving 0.25 degree  GDAS/FNL analysis and forecast (hours 3, 6, 9) globally gridded data in GRIB2 format.

We call it ds083.3: NCEP GDAS/FNL 0.25 Degree Global Tropospheric Analyses and Forecast Grids.

I hope you call it useful.  ;-)

The analysis files are named gdas1.fnl0p25.YYYYMMDDHH.f00.grib2.

You may be able to find and download FNL at this resolution from NCEI beginning in mid-January 2015, but the RDA archive begins in July 2015 with gdas1.fnl0p25.2015070800.f00.grib2.

Forecast grids corresponding to 3, 6 and 9 hours after analysis time are named gdas1.fnl0p25.YYYYMMDDHH.fFH.grib2 where Forecast Hour, FH, can be 03, 06, 09.

wrfhelp@ucar.edu expects most WRF users will see forecast improvement with 0.25 degree instead of 1.0 degree input.  You can use a series of f00 analysis files to provide initial conditions and lateral boundary conditions for your WRF run.  You can also add forecast files to extend your WRF run past the time of the latest available FNL analysis file.

Each 0.25 degree GDAS/FNL analysis file is about ~180 MB while the corresponding 1.0 degree file is  ~17 MB.

Also note that the forecast 0.25 degree grids are ~205 MB because they include water (APCP, ACPCP, PRATE...) and cloud variables that are not in the analysis grids.  This is why some people call the analysis grids "dry".

Please order subsets of the global grids in order to efficiently use shared bandwidth.

We will not be back-filling the 0.25 degree GDAS/FNL to Jan 2015.  If you need FNL files we don't offer, order them directly from NOAA.