This is the footer WRF Basics Weather Research and Forecasting

What is it?  State of the art numerical weather forecasting model  Useful from many km scale down to 100s of m  Geographical dataset accounts for orography, land use, vegetation type, albedo, etc.  Full range of sophisticated boundary layer schemes, microphysical schemes, Cumulus schemes, turbulence, soil moisture,... etc  International user base; well supported  Run from linux/unix using paralell processors  Free!!

WRFV3 flow chart

WRF: Overview Decide upon which domain you wish to use Acquire some met. data for the dates you are interested in Run the WPS WRF Preprocessing System Run WRF Stages in running WRF

Decide upon which domain you wish to use Acquire some met. data for the dates you are interested in Run the WPS Run WRF Stages in running WRF

Determining your domain WRF “Domain Wizard”

Outer domain: 9km resolution 100x126 gridpoints Intermediate domain: 3km resolution 55x76 gridpoints Inner domain: 1km resolution 31x40 gridpoints

WRF code  ~ 160,000 lines of code (Fortran90/C/Perl)  But, you don’t need to edit any of it!  To run WRF you only need to edit two ascii files

Decide upon which domain you wish to use* Acquire some met. data for the dates you are interested in Run the WPS Run WRF Stages in running WRF

Acquire some met data (forecast files) GFS data is online Usually the 06Z forecast cycle data is available in the UK mid-afternoon Online: April 21 st 2007 – present Offline: Feb 15 th 2005 – April 20 th 2007

Decide upon which domain you wish to use* Acquire some met. data for the dates you are interested in Run the WPS Run WRF Stages in running WRF

WPS: Pre-processing Edit the “namelist.wps” file This file contains information about: Start and end times Grid definition Location of the ancillary files (land use, orography, etc

WPS: Pre-processing WRF Pre-processing system (WPS) 1) Design the grid formulation for your run 2) Extract the met. data from your input files 3) Interpolate the met. data onto your grid (defined above)

WRF Pre-processing system (WPS) geogrid.exe ungrib.exe metgrid.exe Computes the grid formulation for your run Extracts the met. data from your input files Interpolates the met. data onto your grid (defined above)

Decide upon which domain you wish to use* Acquire some met. data for the dates you are interested in Run the WPS Run WRF Stages in running WRF wrf.exe

For the Arran fieldcourse WRF runs: geogrid.exe ungrib.exe metgrid.exe qsub real_exe.sh qsub wrf_exe.sh OperationOperator effort Computer effort Download forecast files 5 mins30 mins Edit namelist files 2 mins Run WPS and WRF 5 mins6 hours

Decide upon which domain you wish to use* Acquire some met. data for the dates you are interested in Run the WPS Run WRF Examine the output Stages in running WRF

Examining the output WRF output files are enormous (WRF UK output data ~60Gb) One output file per nest; netCDF format Post processing and looking at the output: IDV – Interactive Data Viewer RIP and RIP4 GrADS Vis5D Matlab wrfpost... generic netCDF viewers

23/02/08: 12Z T+60

23/02/08: 12Z T+60 Cloud water mixing ratio = 0.1g / Kg

WRF GNR: 1km results

23/02/08: 12Z (T+60)

Estimated that a third of the world’s population receive their weather forecast via WRF. Adopted by China, India, Korea, etc etc.