{
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  {
   "cell_type": "markdown",
   "id": "607da258",
   "metadata": {},
   "source": [
    "# Rainfall Anomaly Index\n",
    "\n",
    "Based on van Rooy, M.P. (1965). A Rainfall Anomaly Index Independent of Time and Space. Notos."
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fbc30e7f",
   "metadata": {},
   "source": [
    "## Packages"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "dcef936f",
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib as mpl\n",
    "import matplotlib.pyplot as plt\n",
    "import pandas as pd\n",
    "\n",
    "from spei.rai import mrai, rai"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "40d04848",
   "metadata": {},
   "source": [
    "## Data"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "0c274c53",
   "metadata": {},
   "outputs": [],
   "source": [
    "df = pd.read_csv(\"data/DEBILT.csv\", index_col=0, parse_dates=True)\n",
    "prec = df[\"Prec [m/d] 260_DEBILT\"].multiply(1e3).resample(\"MS\").sum()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "edfc521d",
   "metadata": {},
   "source": [
    "## Calculate Index"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "11dcd5f4",
   "metadata": {},
   "outputs": [],
   "source": [
    "ra_index = rai(prec)\n",
    "mra_index = mrai(prec, sf=1.7)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a6dc3eeb",
   "metadata": {},
   "source": [
    "## Visualize"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "92253a3f",
   "metadata": {},
   "outputs": [],
   "source": [
    "f, ax = plt.subplots(2, 1, figsize=(12, 6), sharex=True, sharey=True)\n",
    "ax[0].plot(ra_index.index, ra_index.values, color=\"C0\")\n",
    "ax[1].plot(mra_index.index, mra_index.values, color=\"C1\")\n",
    "ax[0].set_ylabel(\"Rainfall Anomaly Index\")\n",
    "ax[1].set_ylabel(\"Modified Rainfall Anomaly Index\")\n",
    "ax[0].grid(True)\n",
    "ax[1].grid(True)\n",
    "ax[1].yaxis.set_major_locator(mpl.ticker.MultipleLocator(1))\n",
    "ax[1].xaxis.set_major_locator(mpl.dates.YearLocator(1))\n",
    "ax[1].set_xlim(pd.Timestamp(\"2010-01-01\"), pd.Timestamp(\"2020-12-31\"))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fc772d44",
   "metadata": {},
   "source": [
    "Interpretation based on Hansel (2015) - [The Modified Rainfall Anomaly Index (mRAI)](https://doi.org/10.1007/s00704-015-1389-y)\n",
    "\n",
    "| RAI                                 | Description                   | mRAI                  | Description                   |\n",
    "| :---------------------------------- | :---------------------------- | :-------------------------------- | :---------------------------- |\n",
    "| $\\ge$ 3.00                           | Extremely wet                 | $\\ge$ 2.00                     | Extremely wet                 |\n",
    "| 2.00 to 2.99                        | Very wet                      | 1.50 to 1.99                  | Very wet                      |\n",
    "| 1.00 to 1.99                        | Moderately wet                | 1.00 to 1.49                  | Moderately wet                |\n",
    "| 0.50 to 0.99                        | Slightly wet                  | 0.50 to 0.99                  | Slightly wet                  |\n",
    "| -0.49 to 0.49                       | Near normal                   | -0.49 to 0.49                 | Near normal                   |\n",
    "| -0.99 to -0.50                       | Slightly dry                  | -0.99 to -0.50                 | Slightly dry                  |\n",
    "| -1.99 to -1.00                       | Moderately dry                | -1.49 to -1.00                 | Moderately dry                |\n",
    "| -2.99 to -2.00                       | Very dry                      | -1.99 to -1.50                 | Very dry                      |\n",
    "| ≤-3.00                           | Extremely dry                 | ≤-2.00                     | Extremely dry                 |"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "75058050",
   "metadata": {},
   "source": []
  }
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