GaussianDispersion

AbstractDispersionFunctions

Define types for representing functions to compute the dispersion coefficients with respect to the downwind distance x in meter. Those types must implement the sigma_y and sigma_z methods that both return a closure for calculating σ_y and σ_z respectively. Instanciating those types give a functor that takes as argument the downwind distance and return the dispersion coefficients.

struct GaussianPlume{M, T}

Structure related to the release conditions

• release: release parameters

• meteo: parameters related to the atmospheric conditions

• dispcoefs: object representing the dispersion coefficients

• reflection: if ground reflection is considered

• _z_exp_terms

struct HeatBalanceParams{C, A, B}

Values for the heat balance parametrization.

• 'albedo' :
• C_g: parameter for the estimation of the heat flux to the ground in the equation $q\_G = C\_G R\_n$.

Typical values are 0.05-0.25 for rural, 0.25-0.3 for urban and 0.1 for grasslands (Scire et al., 2000)

PGStability <: AbstractPGStability

Define the stability classes for the model according to Pasquill and Gifford. #! If multiple classes are defined, the average result for each class is considered.

Example

julia> pgstab = PGStability(:A)
PGStability(GaussianDispersion.PGVeryUnstable())

PGStabilityClass

Abstract type of Pasquill-Gifford stability classes. The concrete types start with PG followed by the letter from Pasquill-Gifford classes (A, B, C, D, E, F).

Reference

(Pasquill, 1961; Gifford, 1961).

struct ReleaseParams{T}

Structure related to the release conditions

• h: Effective source height [m]

• Q: Emission rate [g/s]

• Ts: Gas temperature out of the stack [K]

albedo_elevation(albedo_90, ϕ) -> Any

Albedo given albedo_90 the albedo at 90° and ϕ the solar elevation

buoyancy_flux_param(
    gas_density,
    air_density,
    stack_radius,
    gas_velocity
)

Buoyancy flux parameter according to Briggs (1968).

buoyancy_plume_rise(flux_param, x, u)

Plume rise Δh [m] according to Briggs (1975) parametrization for buoyancy dominated plumes. x is the downwind distance in meter and u the downwind velocity in meter/second.

friction_temp(q, rho, u_star, c_p) -> Any

Calculate the friction temperature from the surface pressure p [Pa], temperature t [K], dewpoint temp td [K] and stress stress [N/m²].

Arguments

• q: surface sensible heat flux [W/m²]
• rho: air density [kg/m³]
• u_star: scale velocity [m/s]
• c_p: specific heat capacities of dry air [J/kg/K]

friction_velocity(p, t, td, stress, R_gas) -> Any

Calculate the friction velocity from the surface pressure p [Pa], temperature t [K], dewpoint temp td [K] and stress stress [N/m²].

friction_velocity(u_m, z_m, z_0; karman) -> Any

Calculate the friction velocity from a velocity u_m measured at z_m on a surface of roughness length z_0.

height_hs(p, ps, R_gas, T, g) -> Any

Get height from pressure level in a hydrostatic atmosphere.

height_isa(p, R_gas, g) -> Any

Get height from pressure level in the international standard atmosphere.

hour_angle(t) -> Any
hour_angle(t, t0) -> Any

t the time in hour and t0 the time of the solar noon.

log_wind_profile(u_star, z, z_0, L; karman) -> Any

Calculate the log wind velocity profile.

Arguments

• u_star: friction velocity [m/s]
• z: height [m]
• z_0: roughness length [m]
• L: Obukhov length [m]

momentum_flux_param(
    gas_density,
    air_density,
    stack_radius,
    gas_velocity
)

Momentum flux parameter according to Briggs (1968).

momentum_plume_rise(flux_param, x, u)

Plume rise Δh [m] according to Briggs (1975) parametrization for momentum dominated plumes. x is the downwind distance in meter and u the downwind velocity in meter/second.

net_radiation(R, albedo, cloud_cover, T_surf) -> Any

Net radiation energy flux received by the earth surface [W m^-2] with R the solar flux (solar_energy_flux)

obukhov(ps, ts, u_star, q; c_p, R_gas, karman, g) -> Any

Calculate Obukhov scale height from surface meteorological data and sensible heat flux.

Arguments

• ps: surface pressure [Pa]
• ts: surface temperature [K]
• u_star: scale velocity [m/s]
• q: surface sensible heat flux [W/m2]

obukhov(
    ps,
    ts,
    td,
    t,
    p,
    u_star,
    q;
    c_p,
    R_gas,
    karman,
    g
) -> Any

Calculate Obukhov scale height from surface meteorological data and sensible heat flux.

Arguments

• ps: surface pressure [Pa]
• ts: surface temperature [K]
• td: surface dew point [K]
• t: temperature first model level [K]
• p : pressure first model level [Pa]
• u_star: scale velocity [m/s]
• q: surface sensible heat flux [W/m2]

pasquill_gifford(criteria::AbstractSkyCondition, windspeed::Real)

Return a list of stability classes according to the Pasquill Gifford criteria

Example

julia> pasquill_gifford(Moderate, 5.5) Set{StabilityClass} with 2 elements: C D

potential_temp(t, p, akap) -> Any

Calculate the potential temperature.

Arguments

• t: temperature [K]
• p: pressure [Pa]
• R_gas: individual gas constant for dry air [J/kg/K]
• c_p: specific heat capacities of dry air [J/kg/K]

saturation_pressure(t) -> Any

Calculate the saturation vapor pressure from Arden Buck equations (Buck, 1996). t is in K, result in Pa.

sensible_heat_flux(C_g, net_rad, B) -> Any

Sensible heat flux to the surface [W m^-2]. net_rad can be calculated with net_radiation

solar_declination(day) -> Any

Latitude [°] where the sun is in the zenith at the solar noon. day is the day of the year

solar_elevation(lat, sol_dec, h_angle) -> Any

Solar elevation [°] given the latitude, the solar declination and the hour angle.

solar_energy_flux(Φ, n) -> Any

Solar radiation energy flux W m^-2 given the solar elevation Φ and n the fractional cloud cover. Ref: Kasten and Czeplak, 1980; Holtslag and van Ulden, 1983.

virtual_temp(ps, t, e) -> Any

Calculate the virtual temperature from the surface pressure ps [Pa], the temperature t [K], and the vapor pressure e [Pa].

virtual_temp(t, w) -> Any

Calculate the virtual temperature from the temperature t [K] and the specific humidity w [kg/kg].