text: # The MIT License (MIT)
  #
  # Copyright (c) 2019, TU Wien
  #
  # Permission is hereby granted, free of charge, to any person obtaining a copy
  # of this software and associated documentation files (the "Software"), to deal
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  # furnished to do so, subject to the following conditions:
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  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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  """
  The grid module implements the asymmetrical GMAO 0.5 x 0.625 grid
  used in MERRA2 as a pygeogrids BasicGrid instance.
  """
  
  import numpy as np
  from pygeogrids.grids import BasicGrid
  
  
  def create_merra_cell_grid():
      """
      Function creates the asymmetrical GMAO 0.5 x 0.625 grid as a
      BasicGrid instance.
  
      Returns
      -------
      BasicGrid instance
      """
      # define horizontal and vertical resolution of asymmetrical grid
      lon_res = 0.625
      lat_res = 0.5
  
      # create 361 (lat) x 576 (lon) mesh grid
      lon, lat = np.meshgrid(
          np.arange(-180, 180, lon_res),
          np.arange(-90, 90 + lat_res / 2, lat_res)
      )
      return BasicGrid(lon.flatten(), lat.flatten()).to_cell_grid(cellsize=5.)
  