marsrad (version 1.0.0)

f: Normalized net flux function

Description

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)

Value

Normalized net flux (dimensionless)

Arguments

z

Sun zenith angle [deg]

tau

Atmospheric optical depth (dimensionless)

al

Surface albedo (dimensionless, ranges from 0.1 to 0.4)

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)