HOWTO meteo

GETM supports different kinds of meteorological forcing. The general behaviour is set with the parameters from the meteo namelist in getm.inp.

getm.inp

&meteo
metforcing = .true.           ! use meteorological forcing (default: false)
met_method = 2                ! 1: constant meteo forcing (metforcing=true)
                              ! 2: meteo forcing from file (metforcing=true)
on_grid = .false.             ! true (default): meteo variables are already on grid points (met_method=2)
                              ! false: do interpolation (met_method=2)
calc_met = .true.             ! true: state variables are provided (met_method=2)
                              ! false (default): fluxes are provided (requires on_grid=true)
exchange_method = 1           ! method for bulk fluxes (calc_met=true)
                              ! (except for exchange_method=1 assume neutral stability for barotropic runs)
                              ! 1 (default): Kondo (1975), const Cd=0.00125 for barotropic run
                              ! 2: Kondo (1975)
                              ! 3: Kara et al. (2000)
                              ! 4: Kara et al. (2005) without T10 adjustment
                              ! 5: Kara et al. (2005) incl. T10 adjustment
fwf_method = 2                ! 0 (default): no freshwater flux
                              ! 1: use evap_const and precip_const
                              ! 2: read evaporation and precipitation from file (only for calc_met=true!!!)
                              ! 3: evaporation is calculated, precipitation from file (calc_met=true)
                              ! 4: evaporation is calculated, NO precipitation (calc_met=true)
meteo_ramp = 0                ! spin up wind stress over meteo_ramp time steps (only for met_method=1!!!)
meteo_file = 'meteofiles.dat' ! name of text file with list of netcdf meteo files (met_method=2)
tx = 0.0                      ! constant eastward stress in Pa (met_method=1)
ty = 0.0                      ! constant northward stress in Pa (met_method=1)
albedo_method = 1             ! 0: use albedo_const (also used for met_method=1 OR calc_met=false!!!)
                              ! 1 (default): Payne (calc_met=true)
                              ! 2: Cogley (calc_met=true)
albedo_const = 0.0            ! constant albedo (albedo_method=0)
swr_const = 0.0               ! constant downward surface shortwave radiation in W/m2 (met_method=1)
shf_const = 0.0               ! constant downward surface heat flux in W/m2 (met_method=1)
evap_const = 0.0              ! constant evaporation (<0) in m/s (fwf_method=1)
precip_const = 0.0            ! constant precipitation (>0) in m/s (fwf_method=1)
evap_factor = 1.0             ! factor to convert evaporation to m/s (fwf_method=2)
precip_factor = 1.0           ! factor to convert precipitation to m/s (fwf_method=2,3)
/

For met_method=2 a list of netcdf files is specified in meteofiles.dat.

meteofiles.dat

"meteo_2000.nc"
"meteo_2001.nc"
"/work/user/data/meteo.nc"

A netcdf file meteo.nc contains time varying meteorological forcing fields.

meteo.nc

The header of an example netcdf meteo file with the mandatory form for the units attribute of the time variable is given below.

netcdf meteo {
dimensions:
    lon = 68 ;
    lat = 48 ;
    time = UNLIMITED ; // (366 currently)
variables:
    float lon(lon) ;
        lon:long_name = "longitude" ;
        lon:units = "degrees_east" ;
    float lat(lat) ;
        lat:long_name = "latitude" ;
        lat:units = "degrees_north" ;
    double time(time) ;
        time:units = "seconds since 2000-01-01 00:00:00" ;
    float slp(time, lat, lon) ;

    ...
}

Additional mandatory variables are given in the following table.