ESMPy_grid_area.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# ESMPy grid area calculation test"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'7.1.0 beta snapshot'"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "import numpy as np\n",
    "import ESMF\n",
    "ESMF.__version__"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Background\n",
    "\n",
    "From [ESMPy documentation](http://www.earthsystemmodeling.org/esmf_releases/last_built/esmpy_doc/html/grid.html#ESMF.api.grid.Grid), the `grid` class should have area information:\n",
    "\n",
    "    add_user_area (bool) – Set to True to read in the cell area from the grid file;\n",
    "    otherwise, ESMF will calculate it. Defaults to False."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Make fake grid"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(array([-114., -102.,  -90.,  -78.,  -66.,  -54.,  -42.,  -30.,  -18.,\n",
       "          -6.,    6.,   18.,   30.,   42.,   54.,   66.,   78.,   90.,\n",
       "         102.,  114.]),\n",
       " array([-120., -108.,  -96.,  -84.,  -72.,  -60.,  -48.,  -36.,  -24.,\n",
       "         -12.,    0.,   12.,   24.,   36.,   48.,   60.,   72.,   84.,\n",
       "          96.,  108.,  120.]),\n",
       " array([-57., -51., -45., -39., -33., -27., -21., -15.,  -9.,  -3.,   3.,\n",
       "          9.,  15.,  21.,  27.,  33.,  39.,  45.,  51.,  57.]),\n",
       " array([-60., -54., -48., -42., -36., -30., -24., -18., -12.,  -6.,   0.,\n",
       "          6.,  12.,  18.,  24.,  30.,  36.,  42.,  48.,  54.,  60.]))"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "lon = np.linspace(-114, 114, 20)\n",
    "lon_b = np.linspace(-120, 120, 21)\n",
    "lat = np.linspace(-57, 57, 20) # corners\n",
    "lat_b = np.linspace(-60, 60, 21)\n",
    "lon, lon_b, lat, lat_b"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Create Grid object"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "sourcegrid = ESMF.Grid(np.array([20,20]), \n",
    "                       staggerloc = ESMF.StaggerLoc.CENTER,\n",
    "                       coord_sys = ESMF.CoordSys.SPH_DEG)\n",
    "\n",
    "source_lon = sourcegrid.get_coords(0)\n",
    "source_lat = sourcegrid.get_coords(1)\n",
    "source_lon[...], source_lat[...] = np.meshgrid(lon, lat)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Add corners"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [],
   "source": [
    "sourcegrid.add_coords(staggerloc = ESMF.StaggerLoc.CORNER_VCENTER)\n",
    "\n",
    "source_lat_b = sourcegrid.get_coords(coord_dim = 1, \n",
    "                                     staggerloc = ESMF.StaggerLoc.CORNER)\n",
    "source_lon_b = sourcegrid.get_coords(coord_dim = 0, \n",
    "                                     staggerloc = ESMF.StaggerLoc.CORNER)\n",
    "\n",
    "source_lon_b[...], source_lat_b[...] = np.meshgrid(lon_b, lat_b)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Check area"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Doesn't exist..."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[None, None, None, None]"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "sourcegrid.area"
   ]
  }
 ],
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