[Wrf-users] Senstive experiments.... [SEC=UNCLASSIFIED]

[Chris.Thomas at ga.gov.au]

Hello,

You can modify the WRF Fortran code, but are you doing real cases? If so:

1) How to set the land surface to a uniform height at sea level.

One way to do this that doesn't involve modifying the WRF code is to produce a dataset with the same format as one of the supplied topography datasets, but containing all zeros. This is rather easy to do with unix commands, for example

dd if=/dev/zero of=my_tmp_outfile bs=2 count=1000

will produce a binary file called my_tmp_outfile representing 1000 2 byte integers each containing zero. Just pick one of the existing topographical data sets supplied with WRF, change 1000 to the correct file size, copy my_tmp_outfile to files with the appropriate names, and copy the index file. You will also need to add lines to the GEOGRID.TBL to deal with the new dataset that you have created, and modify your namelist.wps to use the new dataset.

2) How to replaces the land mass with water having a sea surface temperature (SST) set to 301.2 K. You can relatively easily produce a custom landuse dataset that only contains water, similar to producing the flat topography, but then you have to get into the LANDUSE.TBL etc and it is a bit of a mess. Another way might be to modify the met_em files directly. For example you can use a perl script that operates directly on the CDL (text) specification of the met_em files to modify various things. eg

ncdump met_em_file | my_perl_script | ncgen -o new_met_em_file

I do this for various purposes. It is quite slow, and if you want to do a lot of this then some Fortran or C code that operates directly on a netcdf file would be better, but if you want a quick and dirty solution then this works fine. Perl is a good choice for manipulating these text files. Actually if you only want to do it once or twice then you could even do it by hand.

Regards

Chris


-----Original Message-----
From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On Behalf Of Seshagiri Rao
Sent: Wednesday, 5 August 2009 6:28 PM
To: wrf users; wrf help
Subject: [Wrf-users] Senstive experiments....

Dear All,

I read paper in that two experiments are carried out. May any one from you state how i can do this for WRF model i am running......


1) How to set the land surface to a uniform height at sea level.


2) How to replaces the land mass with water having a sea surface temperature (SST) set to 301.2 K.


Thanks for help in advance .....................


Seshu


*****************************************
K.Seshagiri Rao,
IITM Research Fellow,
Climatology & Hydrometeorology Division,
Indian Institute of Tropical Meteorology,
Pune -411 008, India.
Phone:020-25893600Ext363
Mobile: +91 9850957963.



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