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Normalized net flux function

Source: R/f.R
f.Rd

Calculates the normalized net solar flux on the Martian surface accounting for multiple wavelength and multiple scattering in the atmosphere. Based on Pollack's calculations presented in Appelbaum & Flood (1990). Can use polynomial expression or lookup tables.

Usage

f(z, tau, al = 0.1)

Arguments

z

Sun zenith angle [deg]

tau

Atmospheric optical depth (dimensionless)

al

Surface albedo (dimensionless, ranges from 0.1 to 0.4)

Value

Normalized net flux (dimensionless)

Environment Variables

The function behavior can be configured via environment variables:

NET_FLUX_FUNCTION_TYPE: Controls which implementation to use:

  • "polynomial" (default) - Analytical polynomial expression with ~0.7% mean error. Maximum error ~7% at zenith angles 80-85° and tau > 5.

  • "lookup_v1" - Lookup table from NASA TM-102299. Albedo fixed at 0.1.

  • "lookup_v2" - Lookup table from NASA TM-103623. Supports albedo 0.1 and 0.4.

Set with: Sys.setenv(NET_FLUX_FUNCTION_TYPE = "polynomial")

NET_FLUX_FUNCTION_SHOW_WARNINGS: Controls warning display (TRUE/FALSE, default: TRUE). Warnings are shown when polynomial calculations may have notable error margin (tau > 5 or z >= 80°).

Set with: Sys.setenv(NET_FLUX_FUNCTION_SHOW_WARNINGS = TRUE)