Albedo Irradiance Calculator

Author: Prachi Bisht Date: 06-05-2024

Overview

albedoIrradiance.py script calculates the irradiance due to earthshine/albedo on a LEO spacecraft at a given time and (latitude, longitude, altitude) using CERES (Clouds and the Earth’s Radiant Energy System) Data Products: EBAF (for top-of-atmosphere, TOA incoming solar flux) and SYN1Deg (for top-of-atmosphere, TOA albedo).

Use case: quantify the earthshine irradiance on photovoltaics like solar panels/sun sensors aboard a LEO spacecraft

See 'demo.py' for guidance.

Function

getEarthAlbedodf(filename)

input:
    1). albFilename: albedo file from 
                  https://ceres.larc.nasa.gov/data/#syn1deg-level-3 (SYN1deg)
	      for the specified date/month

    2). inFilename: incoming solar flux file from 
                  https://ceres.larc.nasa.gov/data/#energy-balanced-and-filled-ebaf (EBAF)
	      for the specified date/month

Output:
1). global dataframe containing:
['lat', 'lon', 'cell_area', 'albedo']
of earth for the date/month 'inFilename'/'albFilename' was collected for

Function

getIrradianceAtSat(at_time, sc_lat, sc_lon, sc_alt)

Input:
1). at_time: time eg. "23-12-2023  00:00:13"
2). sc_lat: spacecraft latitude (degrees)
3). sc_lon: spacecraft longitude (degrees)
4). sc_alt: spacecraft altitude (km)

Output:
1). dataframe containing:
       ['lat', 'lon', 'cell_area', 'albedo',
      'dot_prod_with_sun', 'sunlit_flag', 
      'dot_prod_with_sat', 'irradiance']
    all within the S/C field of view

2). albedo irradiance on a LEO S/C in W/m^2

Requirements

• numpy==1.21.5
• pandas==1.3.3
• astropy==4.3.1

You can install these dependencies using pip:

pip install -r requirements.txt

Usage

1. Place your albedo data CSV file in the subdirectory 'albedo_dataset'.
2. Update the filename (albedo data CSV file), sc_lat, sc_lon, sc_alt, and at_time variables in the main function with your desired values.
3. Run the script:

python albedoIrradiance.py

4. The script will output the irradiance at the specified location and time in Watts per square meter (W/m^2).

Example

Location: (22°, 88°, 740km) Time: 23-12-2023 00:00:13 Irradiance: [irradiance] W/m^2