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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.

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slide1

WRF Basics

Weather Research and Forecasting

This is the footer

slide2

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!!
wrf overview
WRF: Overview

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 WRF Preprocessing System

Run WRF

slide5

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

determining your domain
Determining your domain

WRF “Domain Wizard”

slide7

Outer domain:

9km resolution

100x126 gridpoints

Intermediate domain:

3km resolution

55x76 gridpoints

Inner domain:

1km resolution

31x40 gridpoints

slide11

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

slide12

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

acquire some met data forecast files
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 21st 2007 – present

Offline: Feb 15th 2005 –

April 20th 2007

slide14

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

wps pre processing
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

slide16

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)

slide17

WRF Pre-processing system (WPS)

Computes the grid formulation for your run

geogrid.exe

ungrib.exe

metgrid.exe

Extracts the met. data from your input files

Interpolates the met. data onto your grid (defined above)

slide18

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

wrf.exe

slide19

For the Arran fieldcourse WRF runs:

geogrid.exe

ungrib.exe

metgrid.exe

qsub real_exe.sh

qsub wrf_exe.sh

slide20

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

Examine the output

examining the output
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

slide22

23/02/08:

12Z

T+60

slide23

23/02/08:

12Z

T+60

Cloud water mixing ratio = 0.1g / Kg

slide25

23/02/08:

12Z

(T+60)

slide26

Estimated that a third of the world’s population receive their weather forecast via WRF.

Adopted by China, India, Korea, etc etc.