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   "id": "d157bce7-ea0e-45ad-9c4e-7ee254b54d92",
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    "tags": []
   },
   "source": [
    "# ICON Training - Hands-on Session -  HSURF Plot Script\n",
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "82416258-d6c8-4e5f-ab72-f32245cd9da7",
   "metadata": {},
   "source": [
    "This is a Python 3 Jupyter notebook. \n",
    "We will be using [Matplotlib](https://matplotlib.org/), a basic plotting library for the Python programming language and its numerical mathematics extension NumPy. The\n",
    "[Cartopy](https://github.com/SciTools/cartopy) package extends the Matplotlib functionality and offers map projection definitions.\n",
    "\n",
    "We start by loading the necessary modules."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3cc8ce8a-d88e-4367-9aaf-16ea0cc907df",
   "metadata": {},
   "outputs": [],
   "source": [
    "import pathlib\n",
    "import numpy as np                          # data structures (floating-point arrays)\n",
    "import netCDF4                              # NetCDF I/O library\n",
    "import cartopy\n",
    "from matplotlib import pyplot as plt        # Base library for plotting\n",
    "import matplotlib.colors as mcol            # Color converter"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5171ae24-1fd0-40b3-9262-a32b47d2b3de",
   "metadata": {},
   "source": [
    "Set file locations:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "c365c5ac-0553-4990-934d-087499164a57",
   "metadata": {},
   "outputs": [],
   "source": [
    "filename = \"/pool/data/ICON/ICON_training/exercise_lam/grids/extpar_DOM01.nc\""
   ]
  },
  {
   "cell_type": "markdown",
   "id": "7f0952c7-14f8-4cd6-969b-9e1f5296cc67",
   "metadata": {},
   "source": [
    "Open the NetCDF grid file and load the data sites (cell circumcenters):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0dd83efd-240a-4bfa-b193-8fa1f4bee235",
   "metadata": {},
   "outputs": [],
   "source": [
    "ds = netCDF4.Dataset(filename)\n",
    "cx = np.degrees(np.asarray(ds[\"clon\"]))\n",
    "cy = np.degrees(np.asarray(ds[\"clat\"]))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "ede22306-6f4b-4813-bc28-5ee8900fe1fb",
   "metadata": {},
   "source": [
    "Load external parameters data set from a second file, get min/max::"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "269a30cb-9bd6-40be-b969-90dabe952d68",
   "metadata": {},
   "outputs": [],
   "source": [
    "src_data = np.asarray(ds[\"topography_c\"])\n",
    "\n",
    "plot_min = np.round(np.amin(src_data))\n",
    "plot_max = np.round(np.amax(src_data))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "af50f9c1-2819-4ba1-9558-8e0f34a0f90e",
   "metadata": {},
   "source": [
    "Then we plot with the function `tricontourf`:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cf0eb192-ae02-48bc-9b8b-4756ff26f3ce",
   "metadata": {},
   "outputs": [],
   "source": [
    "fig = plt.figure(figsize=(7, 7))\n",
    "\n",
    "ax = plt.axes(projection=cartopy.crs.PlateCarree())\n",
    "ax.add_feature(cartopy.feature.BORDERS,edgecolor='gray')\n",
    "ax.add_feature(cartopy.feature.COASTLINE,edgecolor='gray')\n",
    "ax.set_aspect(1.3)\n",
    "\n",
    "cmap = mcol.LinearSegmentedColormap.from_list(\"terrain\",plt.get_cmap(\"terrain\")(np.linspace(0.2, 1, 100)))\n",
    "\n",
    "ax.tricontourf(cx, cy, src_data, transform=cartopy.crs.PlateCarree(), cmap=cmap)\n",
    "\n",
    "plt.colorbar(plt.cm.ScalarMappable(cmap=cmap,norm=plt.Normalize(plot_min,plot_max)),ax=ax, orientation='horizontal', label=\"m\")\n",
    "\n",
    "plt.show()\n",
    "fig.savefig(str(pathlib.Path.home()) + \"/icon-training-scripts/exercise_prepare_lam/HSURF.png\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "57398f8f-f9b9-4241-9afc-313dd4c24b55",
   "metadata": {},
   "source": [
    "---\n",
    "\n",
    "*Author info: Deutscher Wetterdienst (DWD) 2025 ::  icon@dwd.de. For a full list of contributors, see CONTRIBUTING in the root directory. License info: see LICENSE file.*"
   ]
  }
 ],
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