{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Recompute u/v from psi/khi (Arpege)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:14.945777Z",
     "iopub.status.busy": "2025-01-13T11:34:14.944551Z",
     "iopub.status.idle": "2025-01-13T11:34:15.475213Z",
     "shell.execute_reply": "2025-01-13T11:34:15.474822Z"
    }
   },
   "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": "2025-01-13T11:34:15.477234Z",
     "iopub.status.busy": "2025-01-13T11:34:15.477017Z",
     "iopub.status.idle": "2025-01-13T11:34:15.617723Z",
     "shell.execute_reply": "2025-01-13T11:34:15.617326Z"
    }
   },
   "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, 'analysis.full-arpege.tl149-c24.fa'), 'r')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:15.619584Z",
     "iopub.status.busy": "2025-01-13T11:34:15.619385Z",
     "iopub.status.idle": "2025-01-13T11:34:15.739340Z",
     "shell.execute_reply": "2025-01-13T11:34:15.738871Z"
    }
   },
   "outputs": [],
   "source": [
    "psi = r.readfield('S050FONC.COURANT')\n",
    "khi = r.readfield('S050POT.VITESSE')\n",
    "# re-compute u/v from psi/khi\n",
    "uv = epygram.fields.psikhi2uv(psi, khi)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:15.741118Z",
     "iopub.status.busy": "2025-01-13T11:34:15.740958Z",
     "iopub.status.idle": "2025-01-13T11:34:16.927124Z",
     "shell.execute_reply": "2025-01-13T11:34:16.926719Z"
    }
   },
   "outputs": [],
   "source": [
    "fig, ax = uv.cartoplot(subsampling=5, vector_plot_method='quiver',\n",
    "                       components_are_projected_on='grid')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Be careful to projections of wind components !"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:16.931682Z",
     "iopub.status.busy": "2025-01-13T11:34:16.931526Z",
     "iopub.status.idle": "2025-01-13T11:34:17.695734Z",
     "shell.execute_reply": "2025-01-13T11:34:17.695244Z"
    }
   },
   "outputs": [],
   "source": [
    "# wrong projection:\n",
    "fig, ax = uv.cartoplot(subsampling=5, vector_plot_method='quiver',\n",
    "                       components_are_projected_on='lonlat')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "#  and stretched grids !"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "execution": {
     "iopub.execute_input": "2025-01-13T11:34:17.700219Z",
     "iopub.status.busy": "2025-01-13T11:34:17.700003Z",
     "iopub.status.idle": "2025-01-13T11:34:18.400171Z",
     "shell.execute_reply": "2025-01-13T11:34:18.399696Z"
    }
   },
   "outputs": [],
   "source": [
    "# map factor due to stretching:\n",
    "fig, ax = uv.cartoplot(subsampling=5, vector_plot_method='quiver',\n",
    "                       components_are_projected_on='grid',\n",
    "                       map_factor_correction=False)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
 ],
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