GLOW2D

This package builds off of the GLobal airglOW model. The GLOW model is evaluated on an altitude grid at a location. For non-zenith observation geometries, the model requires evaluation at multiple points along the line of sight. The glow2d library wraps the glowpython.generic() function to generate the output on a 2D grid in a geocentric (GEO) coordinate system and in a local (ZA, R) coordinate system.

Installation

Directly using pip:

$ pip install glow2d

Indirectly by git clone:

$ git clone https://github.com/sunipkm/glow2d && cd glow2d
$ pip install .

Dependencies

The following non-trivial dependencies are present:

• glowpython
• geomagdata
• geopy
• haversine
• xarray

This code uses glowpython package to run the GLOW model. geomagdata is used to get the $F_{10.7}$ and $A_p$ indices from the new data source.

Usage

For example:

from datetime import datetime
from glow2d import glow2d_polar as grc

time = datetime(2022, 2, 15, 20, 0, 0).astimezone('UTC') # 20:00 hours local in UTC
lat, lon = 42.64981361744372, -71.31681056737486 # location of observation
bearing = 40 # 40 deg northeast, refer to geopy.GreatCircleDistance().destination() for more info.

iono_loc, iono_geo = grc.polar_model(time, lat, lon, bearing, full_output=True) # generate output in local and GEO coordinates

The output datasets are xarray Datasets with the following structure:

• Coordinates:
  • alt_km: Altitude grid (km) [only in GEO coordinates, from ASL]
  • za: Zenith angle (radians) [only in local polar coordinates]
  • r: Radial distance from observation point (km) [only in local polar coordinates]
  • angle: Angle along great circle (radians)
  • energy: Energy grid (eV)
  • state: Neutral/Ionic excitation states (string) [only if production and loss are converted in local polar coordinates]
  • wavelength: Wavelength of emission features in Angstrom (string). Represented as strings to accommodate the LBH band.
  • lat: Latitude (degrees)
  • lon: Longitude (degrees)
  • wave: Solar flux wavelength (Angstrom)
  • dwave: Solar flux wavelength bin width (Angstrom)
  • sflux: Solar flux (W/m^2/Angstrom)
  • tecscale: TEC scale factor (float)
  • altitude: Altitude of observation point (km from ASL) [only in local polar coordinates]
• Data:
  • Dimension ((angle, alt_km) in GEO, (angle, za) in polar):
    • O: Neutral atomic oxygen density (cm^-3)
    • O2: Neutral molecular oxygen density (cm^-3)
    • N2: Neutral molecular nitrogen density (cm^-3)
    • NO: Neutral nitric oxide density (cm^-3)
    • NS: N(4S) density (cm^-3)
    • ND: N(2D) density (not used, set to zero) (cm^-3)
    • NeIn: Electron density (IRI-90), input to GLOW radiative transfer model. (cm^-3)
    • O+: Ion atomic oxygen (4S) density (cm^-3)
    • O+(2P): Ion atomic oxygen (2P) density (cm^-3)
    • O+(2D): Ion atomic oxygen (2D) density (cm^-3)
    • O2+: Ion molecular oxygen density (cm^-3)
    • N+: Ion molecular nitrogen density (cm^-3)
    • N2+: Ion molecular nitrogen density (cm^-3)
    • NO+: Ion nitric oxide density (cm^-3)
    • N2(A): Molecular nitrogen (GLOW) density (cm^-3)
    • N(2P): N(2P) density (cm^-3)
    • N(2D): N(2D) density (cm^-3)
    • O(1S): O(1S) density (cm^-3)
    • O(1D): O(1D) density (cm^-3)
    • NeOut: Electron density (calculated below 200 km for kchem=4 using GLOW model, cm^-3)
    • Te: Electron temperature (K)
    • Ti: Ion temperature (K)
    • Tn: Neutral temperature (K)
    • ionrate: Ionization rate (1/s)
    • pederson: Pederson conductivity (S/m)
    • hall: Hall conductivity (S/m)
    • eHeat: Ambient electron heating rate (eV/cm^3/s)
    • Tez: Total energetic electron energy deposition (eV/cm^3/s)
  • Dimension ((angle, alt_km, wavelength) in GEO, (angle, za, wavelength) in polar):
    • ver: Volume emission rate of various features (1/cm^3/s)
  • Dimension (angle, alt_km, state) in GEO, (angle, za, state) in polar:
    • production: Production rate of various species (1/cm^3/s)
    • loss: Fractional loss rate of various species (1/s)
  • Dimension (energy):
    • precip: Precipitation flux (cm^-2/s/eV)
• Attributes:
  • time: Time of evaluation (ISO 8601 formatted string)
  • glatlon: Geographic latitude and longitude of evaluation (degrees)
  • Q: Flux of precipitating electrons (erg/cm^2/s)
  • Echar: Characteristic energy of precipitating electrons (eV)
  • f107a: 81-day average of F10.7 solar flux (FSU)
  • f107: Present day F10.7 solar flux (FSU)
  • f107p: Previous day F10.7 solar flux (FSU)
  • ap: Magnetic index
  • iscale: Solar flux model. 0: Hinteregger, 1: EUVAC
  • xuvfac: XUV enhancement factor.
  • itail: Low energy tail enabled/disabled.
  • fmono: Monoenergetic energy flux (erg/cm^2).
  • emono: Monoenergetic characteristic energy (keV).
  • jlocal: Local calculation only (disable electron transport).
  • kchem: GLOW chemistry level.

All angles are in radians, and distances in km. Due to the nature of the coordinate transformation, local coordinate outputs do not contain any NaN values.