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coriolis_param (#176)
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‎ncl/ncl_entries/meteorology.ipynb

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@@ -19,7 +19,8 @@
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"- [daylight_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/daylight_fao56.shtml)\n",
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"- [satvpr_temp_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_temp_fao56.shtml)\n",
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"- [satvpr_tdew_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_tdew_fao56.shtml)\n",
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"- [satvpr_slope_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_slope_fao56.shtml)"
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"- [satvpr_slope_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_slope_fao56.shtml)\n",
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"- [coriolis_param](https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml)"
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]
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},
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{
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"\n",
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"{math}`N = \\frac{24}{{\\pi}} {\\omega}_{s}`\n",
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"\n",
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"And {math}`{\\omega}_{s}` is the sunset hour angle in radians [(Chapter 3, Equation 25)](https://www.fao.org/4/X0490E/x0490e07.htm#chapter%203%20%20%20meteorological%20data) {footcite}`allan_fao_1998` which is calculated from the latitude of the observer on Earth ({math}`\\phi`) and the sun's declination ({math}`\\delta`):\n",
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"And {math}`{\\omega}_{s}` is the sunset hour angle in radians [(Chapter 3, Equation 25)](https://www.fao.org/4/X0490E/x0490e07.htm#chapter%203%20%20%20meteorological%20data) {footcite}`allan_fao_1998` which is calculated from the latitude of the observer on Earth ({math}`\\varphi`) and the sun's declination ({math}`\\delta`):\n",
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"\n",
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"{math}`{\\omega}_{s} = arccos[-tan({\\phi})tan({\\delta})]`"
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"{math}`{\\omega}_{s} = arccos[-tan({\\varphi})tan({\\delta})]`"
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]
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},
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{
@@ -265,6 +266,53 @@
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"saturation_vapor_pressure_slope(temp)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## coriolis_param\n",
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"\n",
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"NCL's `coriolis_param` calculates the Coriolis parameter at a given latitude\n",
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"\n",
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"The Coriolis parameter (also known as the Coriolis frequency or the Coriolis coefficient) is calculated as twice the rotation rate ({math}`{\\Omega}`) of the Earth times the sine of the latitude ({math}`{\\varphi}`){footcite}`hobbs_wallace_1997`\n",
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"\n",
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"{math}`f = 2{\\Omega}sin({\\varphi})`\n",
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"\n",
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"The rotation rate depends on the length of the rotation period of the Earth (T) which is defined as one sidereal day (23 hours and 56 minutes):\n",
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"\n",
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"{math}`{\\Omega} = \\frac{2 * {\\pi}}{T} = 7.292\\text{e-5} \\frac{rad}{s}`"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Input: Single Value\n",
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"from metpy.calc import coriolis_parameter\n",
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"from metpy.units import units\n",
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"\n",
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"latitude = 40 # degrees\n",
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"\n",
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"coriolis_parameter(latitude * units.degree).magnitude"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"# Input: List/Array\n",
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"from metpy.calc import coriolis_parameter\n",
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"from metpy.units import units\n",
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"\n",
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"latitude = [-20, 40, 65] # degrees\n",
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"\n",
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"coriolis_parameter(latitude * units.degree).magnitude"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
@@ -283,6 +331,7 @@
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"- [GeoCAT-comp `saturation_vapor_pressure` Documentation](https://geocat-comp.readthedocs.io/en/latest/user_api/generated/geocat.comp.meteorology.saturation_vapor_pressure.html)\n",
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"- [GeoCAT-comp `actual_saturation_vapor_pressure` Documentation](https://geocat-comp.readthedocs.io/en/latest/user_api/generated/geocat.comp.meteorology.actual_saturation_vapor_pressure.html)\n",
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"- [GeoCAT-comp `saturation_vapor_pressure_slope` Documentation](https://geocat-comp.readthedocs.io/en/latest/user_api/generated/geocat.comp.meteorology.saturation_vapor_pressure_slope.html)\n",
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"- [MetPy `coriolis_parameter` Documentation](https://unidata.github.io/MetPy/latest/api/generated/metpy.calc.coriolis_parameter.html)\n",
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"\n",
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"## Additional Reading\n",
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"- [NOAA: Dew Point vs. Humidity](https://www.weather.gov/arx/why_dewpoint_vs_humidity)"

‎ncl/ncl_index/ncl-index-table.csv

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@@ -50,3 +50,4 @@ NCL Function,Description,Python Equivalent,Notes
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`satvpr_temp_fao56 <https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_temp_fao56.shtml>`__,"Compute saturation vapor pressure using temperature as described in FAO 56","``geocat.comp.saturation_vapor_pressure()``",`example notebook <../ncl_entries/meteorology.ipynb#satvpr-temp-fao56>`__
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`satvpr_tdew_fao56 <https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_tdew_fao56.shtml>`__,"Compute actual saturation vapor pressure as described in FAO 56","``geocat.comp.actual_saturation_vapor_pressure()``",`example notebook <../ncl_entries/meteorology.ipynb#satvpr-tdew-fao56>`__
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`satvpr_slope_fao56 <https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_slope_fao56.shtml>`__," Compute the slope of the saturation vapor pressure curve as described in FAO 56","``geocat.comp.saturation_vapor_pressure_slope()``",`example notebook <../ncl_entries/meteorology.ipynb#satvpr-slope-fao56>`__
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`coriolis_param <https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml>`__,"Calculate the Coriolis parameter","``metpy.calc.coriolis_parameter()``",`example notebook <../ncl_entries/meteorology.ipynb#coriolis-param>`__

‎ncl/ncl_raw/meteorology.ncl

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print (temp + "," + slope_satvpr)
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end
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end do
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; coriolis_param
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; Adapted from https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml
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; ncl -n coriolis_param.ncl >> coriolis_param_output.txt
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print("Latitude (Degree), Coriolis Parameter")
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do lat=-90,90
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print(lat + "," + coriolis_param(lat))
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end do

‎ncl/receipts/meteorology.ipynb

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@@ -28,7 +28,8 @@
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"- [daylight_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/daylight_fao56.shtml)\n",
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"- [satvpr_temp_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_temp_fao56.shtml)\n",
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"- [satvpr_tdew_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_tdew_fao56.shtml)\n",
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"- [satvpr_slope_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_slope_fao56.shtml)"
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"- [satvpr_slope_fao56](https://www.ncl.ucar.edu/Document/Functions/Crop/satvpr_slope_fao56.shtml)\n",
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"- [coriolis_param](https://www.ncl.ucar.edu/Document/Functions/Contributed/coriolis_param.shtml)"
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]
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},
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{
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" geocat_satvpr_slope_fao56[temp] = saturation_vapor_pressure_slope(temp)"
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]
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},
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{
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"cell_type": "markdown",
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"id": "3b9ce2e3-833a-4dbc-8d6a-35eb86397b19",
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"metadata": {},
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"source": [
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"### coriolis_param"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "c2646150-8327-4faa-8979-b70e98be9631",
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"metadata": {},
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"outputs": [],
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"source": [
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"#### Collect NCL values for coriolis_param from geocat-datafiles\n",
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"import geocat.datafiles as gdf\n",
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"import numpy as np\n",
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"\n",
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"coriolis_param_data = gdf.get(\n",
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" 'applications_files/ncl_outputs/coriolis_param_output.txt'\n",
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")\n",
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"coriolis_param_data = np.loadtxt(coriolis_param_data, delimiter=',', skiprows=6)"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "9a699cc2-5a21-4a49-92f9-353635036d06",
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"metadata": {},
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"outputs": [],
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"source": [
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"### Collect NCL `coriolis_param_data` value and associated coriolis parameter values\n",
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"ncl_coriolis_param = dict(zip(coriolis_param_data[::, 0], coriolis_param_data[::, 1]))"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "04410fd1-3033-4c6b-812f-e6b12b3e884e",
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"metadata": {},
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"outputs": [],
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"source": [
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"### Calculate MetPy \"coriolis_parameter\"\n",
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"from metpy.calc import coriolis_parameter\n",
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"from metpy.units import units\n",
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"\n",
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"metpy_coriolis_para = {}\n",
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"\n",
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"for lat in range(-90, 90 + 1):\n",
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" metpy_coriolis_para[lat] = coriolis_parameter(lat * units.degree).magnitude"
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]
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},
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{
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"cell_type": "markdown",
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"id": "3237a0bffc6827fc",
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" ncl_satvpr_slope_fao56[key], geocat_satvpr_slope_fao56[key], rel_tol=1e-05\n",
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" ) # within 5 decimal points"
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]
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},
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{
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"cell_type": "markdown",
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"id": "980c82cf-3860-4f46-bb98-65e4bea9f3cf",
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"metadata": {},
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"source": [
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"### coriolis_param"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"id": "1229100a-0e88-46ef-afad-d557b043a713",
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"metadata": {},
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"outputs": [],
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"source": [
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"import math\n",
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"\n",
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"for key in ncl_coriolis_param.keys():\n",
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" assert math.isclose(\n",
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" ncl_coriolis_param[key], metpy_coriolis_para[key], rel_tol=1e-04\n",
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" ) # within 4 decimal points"
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]
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}
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],
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"metadata": {

‎references.bib

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title = {Map projections: A working manual},
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doi = {10.3133/pp1395}
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}
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@book{hobbs_wallace_1997,
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author = {Hobbs, Peter V. and Wallace, John Michael},
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title = {Atmospheric Science: An Introductory Survey},
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year = {1977},
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pages = {277},
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publisher = {Academic Press}
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}

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