Absorption Data

readpar(filename; νmin=0, νmax=Inf, Scut=0, I=[], maxlines=-1, progress=true)

Read an absoption line file from the HITRAN database, which should have the ".par" extension. These files are available at https://hitran.org/lbl after registering for a free account.

Keyword Arguments

• νmin: smallest line wavenumber to include
• νmax: largest line wavenumber to include
• Scut: smallest spectral line intensity
• I: array of isotopologue numbers to include (excludes all others)
• maxlines: maximum number of lines to include (includes only the most intense maxlines lines)
• progress: whether to display the progress meter

A dictionary of vectors is returned, reflecting the definitions from

1. HITRAN website
2. Rothman, Laurence S., et al. "The HITRAN 2004 molecular spectroscopic database." Journal of quantitative spectroscopy and radiative transfer 96.2 (2005): 139-204.

Organizing type for spectral line data of a single gas

Constructors

SpectralLines(par::Dict)

Construct a SpectralLines object from a dictionary of line data. That dictionary can be created with readpar.

SpectralLines(filename, νmin=0, νmax=Inf, Scut=0, I=[], maxlines=-1)

Read a .par file directly into a SpectralLines object. Keyword arguments are passed through to readpar.

readcia(filename)

Read a collision induced absorption data file. These files are available from HITRAN and desribed by this readme. A vector of dictionaries is returned. Each dictionary represents absorption coefficients for a single temperature over a range of wavenumbers. Each dictionary contains:

Organizing type for collision induced absorption data, with data tables loaded into interpolators.

The interpolator objects are described in the BasicInterpolators.jl documentation.

Constructors

CIATables(cia::Vector{Dict}; extrapolate=false, singles=false, verbose=true)

Construct a CIATables object from a dictionary of coefficient data, which can be read from files using readcia. Keywords extrapolate and singles are used to set those fields of the returned object.

CIATables(filename; extrapolate=false, singles=false, verbose=true)

Construct a CIATables object directly from file, using readcia along the way.

Examples

A CIATables object is function-like. To retrieve the absorption coefficient at a given wavenumber [cm$^{-1}$] and temperature [K], use the object like a function.

co2co2 = CIATables("data/cia/CO2-CO2_2018.cia"); #read data
ν = 100; #wavenumber [cm^-1]
T = 288; #temperature [K]
k = co2co2(ν, T) #absorption coefficient [cm^5/molecule^2]

The object interpolates and sums all data tables that contain ν and T. If extrapolate is true, boundary values are included whenever the temperature is out of range. If singles is true, data ranges for a single temperature are included whenever they contain ν.

A CIATables can be passed to the cia function to compute an absorption cross-section with different temperatures and pressures.

co2ch4 = CIATables("data/cia/CO2-CH4_2018.cia"); #read data
ν = 250; #wavenumber [cm^-1]
T = 310 #temperature [K]
Pa = 1e5; #air pressure [Pa]
Pco2 = 40; #CO2 partial pressure [Pa]
Pch4 = 0.1; #CH4 partial pressure [Pa]
σ = cia(ν, co2ch4, T, Pa, Pco2, Pch4) #absorption cross-section [cm^2/molecule]

Container for a CIATables object and the two gasses representing the CIA components. Specializes with the type of each gas for fast retreival of absorption cross-sections from CIA data and partial pressures.

Constructors

CIA(ciatables::CIATables, g₁::Gas, g₂::Gas)

The name and formulae are taken from ciatables.

CIA(ciatables::CIATables, gases::Tuple)

Using the formulae in ciatables, the correct pair of gases is automatically selected from a VarArg collection of gases.

Example

A CIA object is function-like. Use it like a function, passing it wavenumber, temperature, and pressure arguments to compute an absorption cross-section. Underneath, the CIATables object is interpolated and partial pressures are computed using the concentrations stored with the gases.

#load gases
ν = LinRange(1, 2500, 2500);
Ω = AtmosphericDomain((100,350), 8, (0.9,2e5), 16);
co2 = WellMixedGas("data/par/CO2.par", 0.96, ν, Ω);
ch4 = WellMixedGas("data/par/CH4.par", 1e-6, ν, Ω);

#create CIA object
co2ch4 = CIA(CIATables("data/cia/CO2-CH4_2018.cia"), co2, ch4);

#compute a cross-section
ν = 667;
T = 250;
P = 1e5;
σ = co2ch4(ν, T, P)

cia(k, T, Pₐ, P₁, P₂)

Compute a collision induced absorption cross-section

Arguments

• k: absorption coefficient [cm$^5$/molecule$^2$]
• T: temperature [K]
• Pₐ: total air pressure [Pa]
• P₁: partial pressure of first gas [Pa]
• P₂: partial pressure of second gas [Pa]

cia(ν, x::CIATables, T, Pₐ, P₁, P₂)

Compute a collision induced absorption cross-section after retrieving the total absorption coefficient from a CIATables object

Arguments

• ν: wavenumber [cm$^{-1}$]
• x: CIATables object
• T: temperature [K]
• Pₐ: total air pressure [Pa]
• P₁: partial pressure of first gas [Pa]
• P₂: partial pressure of second gas [Pa]

cia(ν::AbstractVector, x::CIATables, T, Pₐ, P₁, P₂)

Compute a vector of collision induced absorption cross-sections, retrieving the total absorption coefficient from a CIATables object.

Arguments

• ν: vector of wavenumbers [cm$^{-1}$]
• x: CIATables object
• T: temperature [K]
• Pₐ: total air pressure [Pa]
• P₁: partial pressure of first gas [Pa]
• P₂: partial pressure of second gas [Pa]

cia(ν, x::CIATables, T, Pₐ, g₁::Gas, g₂::Gas)

Compute a collision induced absorption cross-section, retrieving the total absorption coefficient from a CIATables object and computing partial pressures from gas objects.

Arguments

• ν: vector of wavenumbers [cm$^{-1}$]
• x: CIATables object
• T: temperature [K]
• Pₐ: total air pressure [Pa]
• g₁: gas object representing the first component of the CIA pair
• g₂: gas object representing the second component of the CIA pair

cia!(σ::AbstractVector, ν::AbstractVector, x::CIATables, T, Pₐ, P₁, P₂)

Compute a vector of collision induced absorption cross-sections in-place, retrieving the total absorption coefficient from a CIATables object.

Arguments

• σ: vector to store computed cross-sections
• ν: vector of wavenumbers [cm$^{-1}$]
• x: CIATables object
• T: temperature [K]
• Pₐ: total air pressure [Pa]
• P₁: partial pressure of first gas [Pa]
• P₂: partial pressure of second gas [Pa]