Hello, thank you for any guidance on this matter.
I want to do a polar stereographic grid projection with distortion minimized at 60N. At first I tried using the -Js option, but it was not clear if this could be done. Instead, I tried a PROJ string, like such:
gmt grdproject rtopo_2.0.4/bed_topography.nc -R-130/25/0/52r -J"+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-94 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs" -GNorth_America_base_topo.nc -D80000= -Fe -V -r -C
This PROJ string is based off of EPSG:4313. The +lat_ts option should set the standard parallel. However, the resulting WKT text does not indicate the standard parallel was applied:
grdproject [INFORMATION]: Proj4 string to be converted to WKT:
+proj=stere +lat_0=90 +lat_ts=60 +lon_0=-94 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs
grdproject [INFORMATION]: WKT converted from proj4 string:
PROJCS["unknown",
GEOGCS["unknown",
DATUM["WGS_1984",
SPHEROID["WGS 84",6378137,298.257223563,
AUTHORITY["EPSG","7030"]],
AUTHORITY["EPSG","6326"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.0174532925199433,
AUTHORITY["EPSG","9122"]]],
PROJECTION["Polar_Stereographic"],
PARAMETER["latitude_of_origin",60],
PARAMETER["central_meridian",-94],
PARAMETER["false_easting",0],
PARAMETER["false_northing",0],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]],
AXIS["Easting",SOUTH],
AXIS["Northing",SOUTH]]
For comparison, this is the WKT text for EPSG:4313 (which has a standard parallel at 70N, note the “Latitude of standard parallel” parameter)
WKT
PROJCRS["WGS 84 / NSIDC Sea Ice Polar Stereographic North",
BASEGEOGCRS["WGS 84",
DATUM["World Geodetic System 1984",
ELLIPSOID["WGS 84",6378137,298.257223563,
LENGTHUNIT["metre",1]]],
PRIMEM["Greenwich",0,
ANGLEUNIT["degree",0.0174532925199433]],
ID["EPSG",4326]],
CONVERSION["US NSIDC Sea Ice polar stereographic north",
METHOD["Polar Stereographic (variant B)",
ID["EPSG",9829]],
PARAMETER["Latitude of standard parallel",70,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8832]],
PARAMETER["Longitude of origin",-45,
ANGLEUNIT["degree",0.0174532925199433],
ID["EPSG",8833]],
PARAMETER["False easting",0,
LENGTHUNIT["metre",1],
ID["EPSG",8806]],
PARAMETER["False northing",0,
LENGTHUNIT["metre",1],
ID["EPSG",8807]]],
CS[Cartesian,2],
AXIS["easting (X)",south,
MERIDIAN[45,
ANGLEUNIT["degree",0.0174532925199433]],
ORDER[1],
LENGTHUNIT["metre",1]],
AXIS["northing (Y)",south,
MERIDIAN[135,
ANGLEUNIT["degree",0.0174532925199433]],
ORDER[2],
LENGTHUNIT["metre",1]],
USAGE[
SCOPE["unknown"],
AREA["World - N hemisphere - north of 60°N"],
BBOX[60,-180,90,180]],
ID["EPSG",3413]]
Proj4
+proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs