Atmospheric forcing
File description
In SELFE, atmoserpic forcings include wind, air pressure and temperature, precipitation, humidity and longwave and shortwave fluxes. These are specified in the netcdf files inside sflux/ dir, and conform to the NetCDF Climate and Forecast (CF) Metadata Convention 1.0.
There are 4 types of files in sflux/dir:
- sflux_inputs.txt:
$cat sflux_inputs.txt
&sflux_inputs ! file name
start_year = 1998, ! start year
start_month = 09, ! start month
start_day = 01, ! start day
start_hour = 0.0, ! start hour
utc_start = 0.0, ! offset from UTC in hours, with positive numbers for western hemishpere
/
- sflux_air_1.0*.nc: netcdf files that have time, wind speed, air temperature and pressure and specific humidity; see sample files at [1]
- sflux_prc_1.0*.nc: netcdf files that have precipitation data; see sample files at [2]
- sflux_rad_1.0*.nc: netcdf files that have downward long and short wave radiation fluxes; see sample files at [3]
Using NARR files for your simulation (North America only)
First, make sure the NARR grid covers your hgrid.ll.
In your run directory, mkdir sflux and inside it, create symbolic links to the NARR files. e.g., if you run starts from June 10, 2004 and ends June 20, 2004, then
sflux_air_1.001.nc --> narr_air.2004_06_10.nc
sflux_air_1.002.nc --> narr_air.2004_06_11.nc
...
sflux_air_1.011.nc --> narr_air.2004_06_20.nc
sflux_air_1.012.nc --> narr_air.2004_06_21.nc (extra day to account for time zone difference)
Similarly for sflux_rad_*.nc and sflux_prc_*.nc. The number "1" after "air_" denotes first data set used; you can use up to 2 sets in SELFE (which combines them with some given weights set in sflux_subs.F90); here you only use 1 set.
Don't forget to update sflux_inputs.txt also.
Preparing your own sflux inputs
After familiarize yourself with the NARR files and their format, you may embark on creating your own nc files. The best way is to modify existing matlab scripts (src/Utility/Sflux_nc/readnc*.m) included in the source code bundle, which have extensively in-line comments to guide you along the way.
