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<p style="margin-top:0;margin-bottom:0">Hi,</p>
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<p style="margin-top:0;margin-bottom:0">I am using grib2 data from the RDPA CaPA project (<a href="https://weather.gc.ca/grib/grib2_RDPA_ps10km_e.html" class="OWAAutoLink" id="LPlnk568400" previewremoved="true">https://weather.gc.ca/grib/grib2_RDPA_ps10km_e.html</a>) and
I would like to change the polar stereographic projection to NAD 83/UTM zone 14.</p>
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<p style="margin-top:0;margin-bottom:0">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 ?</p>
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<p style="margin-top:0;margin-bottom:0">Thanks,</p>
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<p style="margin-top:0;margin-bottom:0">Juliette</p>
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<div> gridrot_0 </div>
<div> Size: 493x399</div>
<div> Dimensions: xgrid_0,ygrid_0</div>
<div> Datatype: single</div>
<div> Attributes:</div>
<div> note2 = 'apply formulas to derive u and v components relative to earth'</div>
<div> note1 = 'u and v components of vector quantities are resolved relative to grid'</div>
<div> formula_v = 'Vearth = cos(rot)*Vgrid - sin(rot)*Ugrid'</div>
<div> formula_u = 'Uearth = sin(rot)*Vgrid + cos(rot)*Ugrid'</div>
<div> units = 'radians'</div>
<div> GridType = 'Polar Sterographic Projection (North or South)'</div>
<div> long_name = 'vector rotation angle'</div>
<div> gridlat_0 </div>
<div> Size: 493x399</div>
<div> Dimensions: xgrid_0,ygrid_0</div>
<div> Datatype: single</div>
<div> Attributes:</div>
<div> La1 = 32.5</div>
<div> Lo1 = 225</div>
<div> Lov = 249</div>
<div> Dx = 15</div>
<div> Dy = 15</div>
<div> units = 'degrees_north'</div>
<div> grid_type = 'Polar Sterographic Projection (North or South)'</div>
<div> long_name = 'latitude'</div>
<div> corners = [3.25e+01 2.45e+01 4.63e+01 6.52e+01]</div>
<div> gridlon_0 </div>
<div> Size: 493x399</div>
<div> Dimensions: xgrid_0,ygrid_0</div>
<div> Datatype: single</div>
<div> Attributes:</div>
<div> La1 = 32.5</div>
<div> Lo1 = 225</div>
<div> Lov = 249</div>
<div> Dx = 15</div>
<div> Dy = 15</div>
<div> units = 'degrees_east'</div>
<div> grid_type = 'Polar Sterographic Projection (North or South)'</div>
<div> long_name = 'longitude'</div>
<div> corners = [-1.35e+02 -7.24e+01 -2.10e+01 1.59e+02]</div>
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