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changes.mady.by.user Peter Caldwell

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changes.mady.by.user Charlie Zender

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This page is under construction...explanation and links will be added in the coming days and weeks...feedback welcome!

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Old (flawed) MapfileNew (corrected)Generation:
map_ne30np4_to_fv129x256_aave.150418.ncmap_ne30np4_to_fv129x256_aave.20150901.ncESMF_RegridWeightGen -s ${DATA}/grids/ne30np4_pentagons.091226.nc -d ${DATA}/grids/129x256_SCRIP.20150901.nc -w ${DATA}/maps/map_ne30np4_to_fv129x256_aave.20150901.nc --method conserve --user_areas
map_ne30np4_to_fv257x512_bilin.150418.nc

map_ne30np4_to_fv257x512_bilin.20150901.nc

ESMF_RegridWeightGen -s ${DATA}/grids/ne30np4_pentagons.091226.nc -d ${DATA}/grids/257x512_SCRIP.20150901.nc -w ${DATA}/maps/map_ne30np4_to_fv257x512_bilin.20150901.nc --method bilinear
map_ne120np4_to_fv257x512_aave.150418.ncmap_ne120np4_to_fv257x512_aave.20150901.nc
ESMF_RegridWeightGen -s ${DATA}/grids/ne120np4_pentagons.100310.nc -d ${DATA}/grids/257x512_SCRIP.20150901.nc -w ${DATA}/maps/map_ne120np4_to_fv257x512_aave.20150901.nc --method conserve --user_areas
map_ne120np4_to_fv801x1600_bilin.150418.nc

map_ne120np4_to_fv801x1600_bilin.20150901.nc

ESMF_RegridWeightGen -s ${DATA}/grids/ne120np4_pentagons.100310.nc -d ${DATA}/grids/801x1600_SCRIP.20150901.nc -w ${DATA}/maps/map_ne120np4_to_fv801x1600_bilin.20150901.nc --method bilinear

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 We analyzed the global mean net TOA solar radiation for January, 1979 from an ne30 simulation on the native grid and then with old and mapfiles. Tests were performed with commands of the form "ncwa -w area -v FSNT in.nc out.nc" and "ncwa -w gw -v FSNT in.nc out.nc" where in.nc = famipc5_ne30_v0.3_00003.cam.h0.1979-01.nc for the native grid and a regridded version of that for the other mapfiles. The native grid analysis is independent of mapfile and is show for clarity. Analysis grids produced with conservative regridding should exactly reproduce the native grid results. The "area" and "gw" rows show this is only true for the a new map produced with the the ESMF_RegridWeightGen "–user_area" switch enabled (indicated by the "_ua" in the mapfile name). The reasons for this are subtle, and are ultimately due to the approximation that the grid vertices are always joined by great circle arcs when for regular lat/lon grids, arcs of constant longitude are great circles, but arcs but arcs of constant latitude are not.

Weightingmap_ne30np4_to_ fv129x256_aave.150418.ncmap_ne30np4_to_ fv129x256_aave.20150901.ncmap_ne30np4_to_ fv129x256_aave_ua.20150901.nc
Native
2.441241149902344e+02
2.441241149902344e+02
2.441241149902344e+02
area2.441241149902344e+022.441241149902344e+022.441241149902344e+02
gw
2.441210784912109e+02
2.441210784912109e+02
2.441241149902344e+02
  The same test performed on old and new Gaussian grids produces similar results:
Weightingmap_ne30np4_to_ t42_aave.150418001005.ncmap_ne30np4_to_ t42_aave.20150901.ncmap_ne30np4_to_ t42_aave_ua.20150901.nc
Native2.441241149902344e+022.441241149902344e+022.441241149902344e+02
area2.441241149902344e+022.441241149902344e+022.441241149902344e+02
gw   
2.441290893554688e+02
2.441119842529297e+02
2.441241149902344e+02