Contact: | Jeff Anderson |
Revision: | $Revision: 2801 $ |
Source: | $URL: http://subversion.ucar.edu/DAReS/DART/trunk/cov_cutoff/cov_cutoff_mod.html $ |
Change Date: | $Date: 2007-04-04 22:11:48 -0600 (Wed, 04 Apr 2007) $ |
Change history: | try "svn log" or "svn diff" |
Computes the weight with which an observation should impact a state variable that is separated by a given distance. The distance is in units determined by the location module being used.
types_mod utilities_mod location_mod
use cov_factor_mod, only : | comp_cov_factor |
Optional namelist interface &cov_cutoff_nml may be read from file input.nml.
real(r8) :: comp_cov_factor real(r8), intent(in) :: z_in real(r8), intent(in) :: c type(location_type), optional, intent(in) :: obs_loc integer, optional, intent(in) :: obs_kind type(location_type), optional, intent(in) :: target_loc integer, optional, intent(in) :: target_kind integer, optional, intent(in) :: localization_override
Returns a weighting factor for observation and a target variable (state or observation) separated by distance z_in and with a half-width distance, c. Three options are provided and controlled by a namelist parameter. The optional argument localization_override controls the type of localization function if present. The optional arguments obs_loc, obs_kind and target_loc, target_kind are not used in the default code. They are made available for users who may want to design more sophisticated localization functions.
var | Weighting factor. |
z_in | The distance between observation and target. |
c | Factor that describes localization function. Describes half-width of functions used here. |
obs_loc | Location of the observation. |
obs_kind | Observation kind. |
target_loc | Location of target. |
target_kind | Kind of target. |
localization_override | Controls localization type if present. Same values as for namelist control. |
We adhere to the F90 standard of starting a namelist with an ampersand '&' and terminating with a slash '/'.
namelist / cov_cutoff_nml / select_localization
Contents | Type | Description |
---|---|---|
select_localization | integer | Selects the localization function. 1 = Gaspari-Cohn 5th order polynomial with halfwidth c. 2 = Boxcar with halfwidth c (goes to 0 for z_in > 2c). 3 = ramped boxcar. Has value 1 for z_in < c and then reduces linearly to 0 at z_in = 2c. |
Routine | Message | Comment |
---|---|---|
comp_cov_factor | Illegal value of "select_localization" in cov_cutoff_mod namelist | Only values 1 through 3 select a localization function. |