{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Compute vor/div from u/v"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:20.245144Z",
     "iopub.status.busy": "2025-01-13T11:34:20.244641Z",
     "iopub.status.idle": "2025-01-13T11:34:20.767014Z",
     "shell.execute_reply": "2025-01-13T11:34:20.766507Z"
    }
   },
   "outputs": [],
   "source": [
    "# for figures in notebook\n",
    "%matplotlib inline\n",
    "\n",
    "# import & initialize epygram\n",
    "import epygram\n",
    "epygram.init_env()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:20.769177Z",
     "iopub.status.busy": "2025-01-13T11:34:20.768976Z",
     "iopub.status.idle": "2025-01-13T11:34:20.917589Z",
     "shell.execute_reply": "2025-01-13T11:34:20.917094Z"
    }
   },
   "outputs": [],
   "source": [
    "import os\n",
    "INPUTS_DIR = os.path.join('..', 'inputs')\n",
    "# open resource in read mode\n",
    "r = epygram.open(os.path.join(INPUTS_DIR, 'ICMSHAROM+0022'), 'r')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:20.919666Z",
     "iopub.status.busy": "2025-01-13T11:34:20.919461Z",
     "iopub.status.idle": "2025-01-13T11:34:22.970406Z",
     "shell.execute_reply": "2025-01-13T11:34:22.969910Z"
    }
   },
   "outputs": [],
   "source": [
    "u = r.readfield('S080WIND.U.PHYS')\n",
    "v = r.readfield('S080WIND.V.PHYS')\n",
    "# re-compute u/v from psi/khi\n",
    "uv = epygram.fields.make_vector_field(u, v)\n",
    "spgeom = u.spectral_geometry\n",
    "uv.sp2gp()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:22.972413Z",
     "iopub.status.busy": "2025-01-13T11:34:22.972274Z",
     "iopub.status.idle": "2025-01-13T11:34:23.702091Z",
     "shell.execute_reply": "2025-01-13T11:34:23.701577Z"
    }
   },
   "outputs": [],
   "source": [
    "fig, ax = uv.cartoplot(subsampling=5, vector_plot_method='quiver',\n",
    "                       components_are_projected_on='grid')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:23.707038Z",
     "iopub.status.busy": "2025-01-13T11:34:23.706871Z",
     "iopub.status.idle": "2025-01-13T11:34:23.723629Z",
     "shell.execute_reply": "2025-01-13T11:34:23.723190Z"
    }
   },
   "outputs": [],
   "source": [
    "# fields need to be spectral to compute vor/div : spectral derivatives are used\n",
    "uv.gp2sp(spgeom)\n",
    "vor, div = uv.compute_vordiv()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:23.725363Z",
     "iopub.status.busy": "2025-01-13T11:34:23.725171Z",
     "iopub.status.idle": "2025-01-13T11:34:24.362899Z",
     "shell.execute_reply": "2025-01-13T11:34:24.362405Z"
    }
   },
   "outputs": [],
   "source": [
    "# map factor due to stretching:\n",
    "fig, ax = vor.cartoplot()\n",
    "fig, ax = div.cartoplot()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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