get_opt_atm_prfl: Get optical properties of atmospheric layers

In AlexCast/apsfs: Monte Carlo code for simulation of atmospheric Point Spread Functions and spatially-resolved Spherical Albedo Functions

Get optical properties of atmospheric layers

Description

Calculates the average optical properties per atmosphere layer for a given atmospheric profile.

Usage

get_opt_atm_prfl(
  atm,
  tau_aer,
  H_aer,
  w0_aer,
  tau_ray_z,
  a_mol_z,
  nlayers = 1000
)

Arguments

atm	A data.frame with columns "Z" (Km height from surface) and "Pressure" (mbar).
tau_aer	Aerosol optical thickness (unitless), [0,Inf).
H_aer	Aerosol scale height (Km), [0,Inf).
w0_aer	Aerosol single scattering albedo (unitless), [0,1].
tau_ray_z	Rayleigh optical thickness (unitless), [0,Inf).
a_mol_z	Molecular absorption profile at the same Z and Pressure points of atm.
nlayers	Number of layers of the output.

Details

Linear interpolation is used for the atmospheric profile of pressure and molecular absorption. The atmosphere is returned as nlayers between the surface (0 km) and the top of the input atmospheric profile.

Pseudo-code: 1 - Get break points of atmosphere layers; 2 - Based on the exponential profile, integrate the aerosol extinction from TOA to surface. 3 - Calculate average aerosol properties per layer. 4 - Based on the pressure profile, get the Rayleigh optical depth profile. 5 - Calculate average Rayleigh scattering per layer. 6 - Integrate molecular absorption from TOA to surface. 7 - Calculate the average molecular absorption per layer. 8 - Calculate the average extinction per layer and single scattering albedo. 9 - Sum the total optical depth from TOA per layer.

Value

A data.frame with the average optical properties per layer. Note that the first two columns are the the break points of the atmosphere layers in km and optical depth. So the last row will always be NA for all average properties, since the last atmosphere layer is nrow - 1.

Examples

data(us76)
tau_ray_z <- rayleigh_od(atm = us76, lambda = 550, co2 = 400, lat = 45)
a_mol_z   <- rep(0, nrow(us76))
get_opt_atm_prfl(atm = us62, tau_aer = 0.5, H_aer = 2, w0_aer = 0.89, 
  tau_ray_z = tau_ray_z, a_mol_z = a_mol_z)

AlexCast/apsfs documentation built on Feb. 1, 2024, 9:48 p.m.