initial checkin of scripts

.gitignore

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+*.nc
+__pycache__/
+

ISMIP7_AIS_multigrid_generator_nc.py

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+# Write ISMIP7 grid files in CDO format
+
+import numpy as np
+from generate_CDO_files_nc import generate_CDO_files
+
+# for checking
+def isaninteger(x):
+    return np.mod(x, 1) == 0
+
+##### Typically the only part a user needs to modify
+# Specify various ISM grids at different resolution
+rk = [16]
+#rk = [32, 16, 8, 4, 2, 1]
+#rk = [0.5]
+
+# Choose which output file to write
+flag_nc = True
+flag_xy = True
+flag_af2 = True
+#####
+
+# Output angle type (degrees or radians)
+output_data_type = 'degrees'
+
+# Write additional g0 grid files
+flag_g0 = False
+
+# Mapping information. This is EPSG 3031 for AIS
+proj_info = {}
+proj_info['earthradius'] = 6378137.0
+proj_info['eccentricity'] = 0.081819190842621
+proj_info['standard_parallel'] = 71.
+proj_info['longitude_rot'] = 0.
+proj_info['hemisphere'] = 'south'
+# Offset of grid node centers. Lower left corner coordinates.
+# Note sign change compared to matlab version!
+proj_info['falseeasting'] = -3040000
+proj_info['falsenorthing'] = -3040000
+
+# Grid dimensions of 1 km base grid
+nx_base = 6081
+ny_base = 6081
+
+
+# g1 grid where ice thickness and SMB are defined
+grids1 = []
+for r in rk:
+    # For any resolution but check integer grid numbers
+    nx = ((nx_base-1)/r)+1
+    ny = ((ny_base-1)/r)+1
+    if isaninteger(nx) and isaninteger(ny):
+        agrid = {}
+        agrid['dx'] = r*1000.
+        agrid['dy'] = r*1000.
+        agrid['nx'] = int(nx)
+        agrid['ny'] = int(ny)
+        agrid['offsetx'] = 0.
+        agrid['offsety'] = 0.
+        agrid['LatLonOutputFileName'] = 'grid_ISMIP7_g1_AIS_{:05d}m.nc'.format(int(r*1000))
+        agrid['xyOutputFileName'] = 'xy_ISMIP7_g1_AIS_{:05d}m.nc'.format(int(r*1000))
+        agrid['af2OutputFileName'] = 'af2_ISMIP7_g1_AIS_{:05d}m.nc'.format(int(r*1000))
+        grids1.append(agrid)
+    else:
+        print('Warning: resolution {} km is not comensurable, skipped.'.format(r))
+
+# Create grids and write out
+for agrid in grids1:
+    #print(agrid)
+    success = generate_CDO_files(agrid, proj_info, output_data_type, flag_nc, flag_xy, flag_af2)
+
+
+if flag_g0:
+    # g0 grid where horizontal velocities are defined e.g. for CISM 
+    grids0 = []
+    for r in rk:
+        # For any resolution but check integer grid numbers
+        nx = ((nx_base-1)/r)
+        ny = ((ny_base-1)/r)
+        if isaninteger(nx) and isaninteger(ny):
+            agrid = {}
+            agrid['dx'] = r*1000.
+            agrid['dy'] = r*1000.
+            agrid['nx'] = int(nx)
+            agrid['ny'] = int(ny)
+            # g0 grid is offset by half a grid size
+            agrid['offsetx'] = r*1000./2.
+            agrid['offsety'] = r*1000./2.
+            agrid['LatLonOutputFileName'] = 'grid_ISMIP7_g0_AIS_{:05d}m.nc'.format(int(r*1000))
+            agrid['xyOutputFileName'] = 'xy_ISMIP7_g0_AIS_{:05d}m.nc'.format(int(r*1000))
+            agrid['af2OutputFileName'] = 'af2_ISMIP7_g0_AIS_{:05d}m.nc'.format(int(r*1000))
+            grids0.append(agrid)
+        else:
+            print('Warning: resolution {} km is not comensurable, skipped.'.format(r))
+
+            # Create grids and write out
+            for agrid in grids0:
+                #print(agrid)
+                success = generate_CDO_files(agrid, proj_info, output_data_type, flag_nc, flag_xy, flag_af2)

ISMIP7_GrIS_multigrid_generat0r_nc.py

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+# Write ISMIP7 grid files in CDO format
+
+import numpy as np
+from generate_CDO_files_nc import generate_CDO_files
+
+# for checking
+def isaninteger(x):
+    return np.mod(x, 1) == 0
+
+##### Typically the only part a user needs to modify
+# Specify various ISM grids at different resolution
+rk = [16]
+#rk = [16, 8, 4, 2, 1]
+#rk = [0.5]
+
+# Choose which output file to write
+flag_nc = True
+flag_xy = True
+flag_af2 = True
+#####
+
+# Output angle type (degrees or radians)
+output_data_type = 'degrees'
+
+# Write additional g0 grid files
+flag_g0 = False
+
+# Mapping information. This is EPSG 3413 for GrIS
+proj_info = {}
+proj_info['earthradius'] = 6378137.0
+proj_info['eccentricity'] = 0.081819190842621
+proj_info['standard_parallel'] = 70.
+proj_info['longitude_rot'] = 315.
+proj_info['hemisphere'] = 'north'
+# Offset of grid node centers. Lower left corner coordinates.
+# Note sign change compared to matlab version!
+proj_info['falseeasting'] = -720000
+proj_info['falsenorthing'] = -3450000
+
+# Grid dimensions of 1 km base grid
+nx_base = 1681
+ny_base = 2881
+
+
+# g1 grid where ice thickness and SMB are defined
+grids1 = []
+for r in rk:
+    # For any resolution but check integer grid numbers
+    nx = ((nx_base-1)/r)+1
+    ny = ((ny_base-1)/r)+1
+    if isaninteger(nx) and isaninteger(ny):
+        agrid = {}
+        agrid['dx'] = r*1000.
+        agrid['dy'] = r*1000.
+        agrid['nx'] = int(nx)
+        agrid['ny'] = int(ny)
+        agrid['offsetx'] = 0.
+        agrid['offsety'] = 0.
+        agrid['LatLonOutputFileName'] = 'grid_ISMIP7_g1_GrIS_{:05d}m.nc'.format(int(r*1000))
+        agrid['xyOutputFileName'] = 'xy_ISMIP7_g1_GrIS_{:05d}m.nc'.format(int(r*1000))
+        agrid['af2OutputFileName'] = 'af2_ISMIP7_g1_GrIS_{:05d}m.nc'.format(int(r*1000))
+        grids1.append(agrid)
+    else:
+        print('Warning: resolution {} km is not comensurable, skipped.'.format(r))
+
+# Create grids and write out
+for agrid in grids1:
+    #print(agrid)
+    success = generate_CDO_files(agrid, proj_info, output_data_type, flag_nc, flag_xy, flag_af2)
+
+
+if flag_g0:
+    # g0 grid where horizontal velocities are defined e.g. for CISM 
+    grids0 = []
+    for r in rk:
+        # For any resolution but check integer grid numbers
+        nx = ((nx_base-1)/r)
+        ny = ((ny_base-1)/r)
+        if isaninteger(nx) and isaninteger(ny):
+            agrid = {}
+            agrid['dx'] = r*1000.
+            agrid['dy'] = r*1000.
+            agrid['nx'] = int(nx)
+            agrid['ny'] = int(ny)
+            # g0 grid is offset by half a grid size
+            agrid['offsetx'] = r*1000./2.
+            agrid['offsety'] = r*1000./2.
+            agrid['LatLonOutputFileName'] = 'grid_ISMIP7_g0_GrIS_{:05d}m.nc'.format(int(r*1000))
+            agrid['xyOutputFileName'] = 'xy_ISMIP7_g0_GrIS_{:05d}m.nc'.format(int(r*1000))
+            agrid['af2OutputFileName'] = 'af2_ISMIP7_g0_GrIS_{:05d}m.nc'.format(int(r*1000))
+            grids0.append(agrid)
+        else:
+            print('Warning: resolution {} km is not comensurable, skipped.'.format(r))
+
+            # Create grids and write out
+            for agrid in grids0:
+                #print(agrid)
+                success = generate_CDO_files(agrid, proj_info, output_data_type, flag_nc, flag_xy, flag_af2)

README.md

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 # generate-ismip7-grid-files-py
 Python scripts to generate ISMIP7 grid description files used for CDO regridding.
+
+## Setup
+Needs a python3 environment with  
+numpy, netCDF4, os
+
+The scripts can generate 3 different types of files for Greenland and Antarctica
+
+### grid description files (needed for CDO regridding)
+  grid_ISMIP7_g?_IS_res.nc
+### xy coordinates 
+  xy_ISMIP7_g?_IS_res.nc
+### area factors 
+  af2_ISMIP7_g?_IS_res.nc
+
+All files are produced for the diagnostic grid g1 (ice thickness, SMB, ..) 
+The scripts can also generate files for a staggered grid g0, where e.g. CISM defines horizontal velocities. 
+  ISMIP7_AIS_multigrid_generator_nc.py  
+  ISMIP7_GrIS_multigrid_generator_nc.py  
+
+using  
+
+  polar_stereo.py  
+  wnc.py  

generate_CDO_files_nc.py

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+# generate CDO lat-lon grid file from xy and mapping information
+import numpy as np
+import os 
+from wnc import wnc, wncatts
+from polar_stereo import polar_xy_to_lonlat, polar_xy_scale_factor2
+
+def generate_CDO_files(agrid, proj_info, output_data_type, flag_nc, flag_xy, flag_af2):
+
+    # Grid parameters
+    dx = agrid['dx']
+    dy = agrid['dy']
+    nx = agrid['nx']
+    ny = agrid['ny']
+    offsetx = agrid['offsetx']
+    offsety = agrid['offsety']
+
+    # Create gridded x and y. Dimension order is y,x!
+    ycenters, xcenters = np.meshgrid((np.arange(ny)*dy), (np.arange(nx)*dx), indexing='ij')
+    #print(xcenters.shape)
+
+    # Generate xy corner coordinates. CDO needs bounds to rotate counterclockwise
+    ycorners, xcorners = np.meshgrid((np.arange(ny+1)*dy-dy/2), (np.arange(nx+1)*dx-dx/2), indexing='ij')
+
+    ybounds = np.zeros([ycenters.shape[0], ycenters.shape[1], 4])
+
+    SEcorner= ycorners[:-1, 1:]
+    ybounds[:,:,0] = SEcorner
+    NEcorner= ycorners[1:, 1:]
+    ybounds[:,:,1] = NEcorner
+    NWcorner= ycorners[1:, :-1]
+    ybounds[:,:,2] = NWcorner
+    SWcorner= ycorners[:-1, :-1]
+    ybounds[:,:,3] = SWcorner
+
+    xbounds = np.zeros([xcenters.shape[0], xcenters.shape[1], 4])
+
+    SEcorner= xcorners[:-1, 1:]
+    xbounds[:,:,0] = SEcorner
+    NEcorner= xcorners[1:, 1:]
+    xbounds[:,:,1] = NEcorner
+    NWcorner= xcorners[1:, :-1]
+    xbounds[:,:,2] = NWcorner
+    SWcorner= xcorners[:-1, :-1]
+    xbounds[:,:,3] = SWcorner
+
+    # Write 2d xy netcdf file
+    if flag_xy:
+        print(f"Generating {agrid['xyOutputFileName']}")
+
+        try:
+            os.remove(agrid['xyOutputFileName'])
+        except OSError:
+            pass
+
+        # write 2D and 1D x,y
+        wnc(xcenters+proj_info['falseeasting']+offsetx, agrid['xyOutputFileName'], 'x2', 'm', 'grid center x-coordinate', ['y', 'x'], 0, 'NETCDF4')
+        wnc(ycenters+proj_info['falsenorthing']+offsety, agrid['xyOutputFileName'], 'y2', 'm', 'grid center y-coordinate', ['y', 'x'], 0, 'NETCDF4')
+
+        wnc(xcenters[0, :]+proj_info['falseeasting']+offsetx, agrid['xyOutputFileName'], 'x1', 'm', 'grid center x-coordinate', 'x', 0, 'NETCDF4')
+        wnc(ycenters[:, 0]+proj_info['falsenorthing']+offsety, agrid['xyOutputFileName'], 'y1', 'm', 'grid center y-coordinate', 'y', 0, 'NETCDF4')
+
+        # write bounds
+        wnc(xbounds+proj_info['falseeasting']+offsetx, agrid['xyOutputFileName'], 'x_bnds', 'm', 'grid corner x-coordinate', ['y', 'x', 'nv4'], 0, 'NETCDF4')
+        wnc(ybounds+proj_info['falsenorthing']+offsety, agrid['xyOutputFileName'], 'y_bnds', 'm', 'grid corner y-coordinate', ['y', 'x', 'nv4'], 0, 'NETCDF4')
+
+
+    ## Write CDO grid netcdf file
+    if flag_nc:
+
+        # Create lat,lon centers
+        LI_grid_center_lon, LI_grid_center_lat, _ = polar_xy_to_lonlat(xcenters+proj_info['falseeasting']+offsetx, ycenters+proj_info['falsenorthing']+offsety, proj_info['standard_parallel'], proj_info['longitude_rot'], proj_info['earthradius'], proj_info['eccentricity'], proj_info['hemisphere'] )
+
+        # Create lat,lon bounds 
+        LI_grid_corner_lon, LI_grid_corner_lat, _ = polar_xy_to_lonlat(xbounds+proj_info['falseeasting']+offsetx, ybounds+proj_info['falsenorthing']+offsety, proj_info['standard_parallel'], proj_info['longitude_rot'], proj_info['earthradius'], proj_info['eccentricity'], proj_info['hemisphere'] )
+
+        # Map to 360 range 
+        LI_grid_center_lon = LI_grid_center_lon % 360.
+        LI_grid_corner_lon = LI_grid_corner_lon % 360.
+
+        # Map to -180 to 180 range, nicer for Greenland
+        LI_grid_center_lon = np.where(LI_grid_center_lon < 180., LI_grid_center_lon, LI_grid_center_lon - 360.)
+        LI_grid_corner_lon = np.where(LI_grid_corner_lon < 180., LI_grid_corner_lon, LI_grid_corner_lon - 360.)
+
+        # Convert to radians if requested
+        if output_data_type == 'radians':
+            LI_grid_center_lat = np.deg2rad(LI_grid_center_lat)
+            LI_grid_center_lon = np.deg2rad(LI_grid_center_lon)
+            LI_grid_corner_lat = np.deg2rad(LI_grid_corner_lat)
+            LI_grid_corner_lon = np.deg2rad(LI_grid_corner_lon)
+
+        print(f"Generating {agrid['LatLonOutputFileName']}")
+
+        try:
+            os.remove(agrid['LatLonOutputFileName'])
+        except OSError:
+            pass
+
+        # grid centers
+        wnc(LI_grid_center_lat, agrid['LatLonOutputFileName'], 'lat', 'degrees_north', 'grid center latitude', ['y', 'x'], 0, 'NETCDF4')
+        wncatts(agrid['LatLonOutputFileName'],'lat','standard_name', 'latitude')
+        wncatts(agrid['LatLonOutputFileName'],'lat','bounds', 'lat_bnds')
+
+        wnc(LI_grid_center_lon, agrid['LatLonOutputFileName'], 'lon', 'degrees_east', 'grid center longitude', ['y', 'x'], 0, 'NETCDF4')
+        wncatts(agrid['LatLonOutputFileName'],'lon','standard_name', 'longitude')
+        wncatts(agrid['LatLonOutputFileName'],'lon','bounds', 'lon_bnds')
+
+        # bounds
+        wnc(LI_grid_corner_lat, agrid['LatLonOutputFileName'], 'lat_bnds', 'degrees_north', 'grid corner latitude', ['y', 'x', 'nv4'], 0, 'NETCDF4')
+        wnc(LI_grid_corner_lon, agrid['LatLonOutputFileName'], 'lon_bnds', 'degrees_east', 'grid corner longitude', ['y', 'x', 'nv4'], 0, 'NETCDF4')
+
+        # dummy needed for mapping
+        wnc(np.int8(LI_grid_center_lon*0+1), agrid['LatLonOutputFileName'], 'dummy', '1', 'dummy variable', ['y', 'x'], 0, 'NETCDF4')
+        # add lat,lon mapping
+        wncatts(agrid['LatLonOutputFileName'],'dummy', 'coordinates', 'lon lat')
+
+    ## Write af2 netcdf file
+    if flag_af2:
+
+        # Create af2, lat,lon centers
+        LI_grid_center_af2 = polar_xy_scale_factor2(xcenters+proj_info['falseeasting']+offsetx, ycenters+proj_info['falsenorthing']+offsety, proj_info['standard_parallel'], proj_info['longitude_rot'], proj_info['earthradius'], proj_info['eccentricity'], proj_info['hemisphere'])
+
+        print(f"Generating {agrid['af2OutputFileName']}")
+
+        try:
+            os.remove(agrid['af2OutputFileName'])
+        except OSError:
+            pass
+
+        # grid centers
+        wnc(LI_grid_center_af2, agrid['af2OutputFileName'], 'af2', 'scale_factor2', 'squared map scale factor', ['y', 'x'], 0, 'NETCDF4')
+
+
+    successfully_completed = True
+