wrf basics weather research and forecasting
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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. - PowerPoint PPT PresentationTRANSCRIPT
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WRF Basics
Weather Research and Forecasting
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http://www.ncas.ac.uk
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!!
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http://www.ncas.ac.uk
WRFV3 flow chart
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http://www.ncas.ac.uk
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
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http://www.ncas.ac.uk
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
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http://www.ncas.ac.uk
Determining your domain
WRF “Domain Wizard”
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Outer domain:9km resolution100x126 gridpointsIntermediate domain:3km resolution55x76 gridpointsInner domain:1km resolution31x40 gridpoints
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http://www.ncas.ac.uk
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http://www.ncas.ac.uk
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http://www.ncas.ac.uk
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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 twoascii files
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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
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http://www.ncas.ac.uk
Acquire some met data (forecast files)
GFS data is online
Usually the 06Z forecast cycledata is available in the UK mid-afternoon
Online:April 21st 2007 – present
Offline: Feb 15th 2005 – April 20th 2007
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http://www.ncas.ac.uk
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
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http://www.ncas.ac.uk
WPS: Pre-processing
Edit the “namelist.wps” file
This file contains informationabout:
Start and end times
Grid definition
Location of the ancillaryfiles (land use, orography, etc
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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)
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http://www.ncas.ac.uk
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)
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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
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For the Arran fieldcourse WRF runs:
geogrid.exeungrib.exemetgrid.exeqsub real_exe.shqsub wrf_exe.sh
Operation Operator effort
Computer effort
Download forecast files
5 mins 30 mins
Edit namelist files
2 mins
Run WPS and WRF
5 mins 6 hours
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http://www.ncas.ac.uk
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
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http://www.ncas.ac.uk
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 ViewerRIP and RIP4GrADSVis5DMatlabwrfpost
... generic netCDF viewers
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23/02/08:
12Z
T+60
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23/02/08:
12Z
T+60
Cloud water mixing ratio = 0.1g / Kg
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WRF GNR: 1km results
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23/02/08:
12Z
(T+60)
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Estimated that a third of the world’s population receive their weather forecast via WRF.
Adopted by China, India, Korea, etc etc.