[ncl-talk] unrotate grib2 data projected into polar stereographic projection
Juliette Lapeyre
Juliette.Lapeyre at USherbrooke.ca
Mon Jan 8 09:01:29 MST 2018
Hi,
I am using grib2 data from the RDPA CaPA project (https://weather.gc.ca/grib/grib2_RDPA_ps10km_e.html) and I would like to change the polar stereographic projection to NAD 83/UTM zone 14.
I can that there are three variables that I should use (gridrot_0, gridlat_0, gridlon_0) but I don't understand how to apply the formulas indicated in gridrot_0 (see below). What are exactly Vearth, Vgrid, Uearth and Ugrid ? I guess "rot" is the value of grid_rot for each coordinate ?
Thanks,
Juliette
gridrot_0
Size: 493x399
Dimensions: xgrid_0,ygrid_0
Datatype: single
Attributes:
note2 = 'apply formulas to derive u and v components relative to earth'
note1 = 'u and v components of vector quantities are resolved relative to grid'
formula_v = 'Vearth = cos(rot)*Vgrid - sin(rot)*Ugrid'
formula_u = 'Uearth = sin(rot)*Vgrid + cos(rot)*Ugrid'
units = 'radians'
GridType = 'Polar Sterographic Projection (North or South)'
long_name = 'vector rotation angle'
gridlat_0
Size: 493x399
Dimensions: xgrid_0,ygrid_0
Datatype: single
Attributes:
La1 = 32.5
Lo1 = 225
Lov = 249
Dx = 15
Dy = 15
units = 'degrees_north'
grid_type = 'Polar Sterographic Projection (North or South)'
long_name = 'latitude'
corners = [3.25e+01 2.45e+01 4.63e+01 6.52e+01]
gridlon_0
Size: 493x399
Dimensions: xgrid_0,ygrid_0
Datatype: single
Attributes:
La1 = 32.5
Lo1 = 225
Lov = 249
Dx = 15
Dy = 15
units = 'degrees_east'
grid_type = 'Polar Sterographic Projection (North or South)'
long_name = 'longitude'
corners = [-1.35e+02 -7.24e+01 -2.10e+01 1.59e+02]
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