Chris Thomas
New member
geogrid does not appear to correctly use the pole_lon namelist variable when specifying a rotated lat-lon projection.
My geogrid namelist (attached) reads:
but it is apparent from the XLAT_M and XLONG_M data in the resulting geo_em files (attached) that the actual pole coordinates used were:
pole_lat = 60.31
pole_lon = 147.63 (instead of the requested 141.38)
For lat-lon coordinates, page 3-10 of WRFUsersGuideV4.2 says the transformation is controlled by parameters pole_lat, pole_lon and stand_lon. I had therefore assumed that ref_lat and ref_lon were redundant for a lat-lon projection. It looks to me like the WPS has either used ref_lon as the pole longitude or has used 180 - stand_lon (which is a guideline only, on 3-13 of user guide). Furthermore the global attributes in the geo_em files (attached) are listed as:
:STAND_LON = 32.37f ;
OLE_LAT = 60.31f ;
OLE_LON = 321.38f ;
which are those requested in the namelist but NOT those actually used.
My geogrid namelist (attached) reads:
Code:
&geogrid
parent_id = 1, 1, 2,
parent_grid_ratio = 1, 5, 4,
i_parent_start = 1, 245, 125,
j_parent_start = 1, 90, 110,
e_we = 540, 381, 641,
e_sn = 363, 501, 601
geog_data_res = 'default','default','default',
dx = 0.176
dy = 0.176
map_proj = 'lat-lon',
ref_lat = -24.26,
ref_lon = 147.63,
pole_lat= 60.31
pole_lon= 321.38
stand_lon = 32.37,
geog_data_path = '/projects/WRF/data/WPS_GEOG/'
/but it is apparent from the XLAT_M and XLONG_M data in the resulting geo_em files (attached) that the actual pole coordinates used were:
pole_lat = 60.31
pole_lon = 147.63 (instead of the requested 141.38)
For lat-lon coordinates, page 3-10 of WRFUsersGuideV4.2 says the transformation is controlled by parameters pole_lat, pole_lon and stand_lon. I had therefore assumed that ref_lat and ref_lon were redundant for a lat-lon projection. It looks to me like the WPS has either used ref_lon as the pole longitude or has used 180 - stand_lon (which is a guideline only, on 3-13 of user guide). Furthermore the global attributes in the geo_em files (attached) are listed as:
:STAND_LON = 32.37f ;
OLE_LAT = 60.31f ;OLE_LON = 321.38f ;which are those requested in the namelist but NOT those actually used.