ProjUtils.md

Module ProjUtils

General Information

• Module Fortran File: ProjUtils.F90

General Description

Module containing utility subroutines for geographical transformations, i.e. fwd (LonLat => xy) and inv. (xy => LonLat) projections.

Usage

In particular the subroutines xy2LonLat(x,y,Lon,Lat) and LonLat2xy(Lon,Lat,x,y), can be used to compute longitude and latitude from x,y projectied coordinates and conversely.

To use it in your own USF or Solver:

<USF or SOLVER>
  USE ProjUtils

  CALL xy2LonLat(x,y,Lon,Lat)
  CALL LonLat2xy(Lon,Lat,x,y)
<>  

Definition of the projection and parameters in the .sif file, Simulation section

Simulation

! Antarctic Polar Stereographic EPSG:3031
  projection type = String "polar stereographic south"
  central_meridian = Real 0.0
  latitude_of_origin = Real -71.0

! NSIDC Sea Ice Polar Stereographic North EPSG:3014
  projection type = String "polar stereographic north"
  central_meridian = Real -45.0
  latitude_of_origin = Real 70.0

End

Currently supported projections:

• polar stereographic projections north and south, i.e. will cover Antarctic and Greenland applications.

  • Implementation of the analytical solutions from J. P. Snyder, Map-projections - A working Manual, 1987

  • see above for the definition of the parameters in the .sif file

• generic from proj4 definition:

  • requires the fortrangis external library with proj support

  • code is ready but currently no support for the compilation; i.e. need to update cmake

Known Bugs and Limitations

Examples

An example to compute longitude and latitude using the USF_proj.F90 user function can be found here [ELMER_TRUNK]/elmerice/Tests/Proj_South