Transcript Running WRF

Running WRF on HECToR
Ralph Burton, NCAS (Leeds)
Alan Gadian, NCAS (Leeds)
With thanks to Paul Connolly, Hector support team
This is the footer
http://www.ncas.ac.uk
WRFV2 flow chart
http://www.ncas.ac.uk
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
Run WRF
Examine the output
* only need to do this once
http://www.ncas.ac.uk
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
* only need to do this once
http://www.ncas.ac.uk
Determining your domain
Where do I want my grid?
What resolution do I need?
How many nests do I want?
Either compute manually and enter your values
into the WRF input files (see later) [ harder ]
or
Use the WRFDomainWizard [ easier ]
http://www.ncas.ac.uk
Determining your domain: WRF domain wizard
http://www.ncas.ac.uk
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
* only need to do this once
http://www.ncas.ac.uk
Acquire some met data (forecast files)
GRIB 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
http://www.ncas.ac.uk
Acquire some met data (forecast files)
Download (FTP) the files from the NOMADS web site:
Frequency of GRIB data varies, but for 1-degree GFS forecast we have
4 cycles / day : 0Z, 6Z, 12Z, 18Z
Forecast hours: analysis, T+3, T+6, ..., T+180
Download speed varies, but each GRIB file (~20Mb)
takes ~ 3 minutes
Do this stage some time before you need to do the run
http://www.ncas.ac.uk
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
* only need to do this once
http://www.ncas.ac.uk
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
http://www.ncas.ac.uk
WPS: Pre-processing
WRF Pre-processing system (WPS)
Computes the grid formulation for your run
geogrid.exe
ungrib.exe
Extracts the met. data from your input (GRIB) files
metgrid.exe
Interpolates the met. data onto your grid (defined above)
http://www.ncas.ac.uk
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
* only need to do this once
http://www.ncas.ac.uk
Running WRF
Edit the “namelist.input” file
Start and end times
http://www.ncas.ac.uk
Running WRF
Edit the “namelist.input” file
Time step and
grid definition
http://www.ncas.ac.uk
Running WRF
Edit the “namelist.input” file
Microphysics;
surface layer;
boundary layer
http://www.ncas.ac.uk
Running WRF
Edit the “namelist.input” file
Dynamics
options
http://www.ncas.ac.uk
Running WRF
For each WRF run, two separate executables need to be run.
real.exe
wrf.exe
these are already compiled; independent of choice
of grid, number of processors requested, microphysics
schemes, timestep, etc etc.
real.exe takes minutes and is run on a few processors. It sets up the
input files required by WRF proper.
wrf.exe is the main body of the code
http://www.ncas.ac.uk
Running WRF
Standard scripts exist for submitting real.exe and wrf.exe
e.g. wrf_exe.sh
This will request 512 dual-core
preocessors; 12 hours wallclock
time
no need to alter
anything below
here
http://www.ncas.ac.uk
Running WRF
Submit the jobs to the queue
qsub real_exe.sh
then
qsub wrf_exe.sh
... and that’s it!
A 60 hour, 3 domain (9 - 3 – 1 km) 60 hr forecast for the UK, output files
every hour, including 2 restart files takes ~10 hours using 512 dual core
processors.
http://www.ncas.ac.uk
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
* only need to do this once
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 Viewer
RIP and RIP4
GrADS
Vis5D
Matlab
wrfpost
... generic netCDF viewers
http://www.ncas.ac.uk
Summary
In short, this is all you need to do:
geogrid.exe
ungrib.exe
metgrid.exe
qsub real_exe.sh
qsub wrf_exe.sh
Operation
Operator
effort
Hector effort
Download
GRIB files
5 mins
40 mins
Edit namelist 2 mins
files
Run WPS
and WRF
5 mins
10 hours
http://www.ncas.ac.uk
Further info
WRF on Hector: full details and examples of UK forecast runs
http://ncasweb.leeds.ac.uk/weather
WRF on Hector: UK forecast runs
http://www.ncas.ac.uk