Surface Fluxes

SurfaceFluxes

Surface flux functions, e.g., for buoyancy flux, friction velocity, and exchange coefficients.

Sub-modules

• module Byun1990
• module Nishizawa2018

Interface

• compute_buoyancy_flux computes the buoyancy flux
• In addition, each sub-module has the following functions:
  • monin_obukhov_len computes the Monin-Obukhov length
  • compute_friction_velocity computes the friction velocity
  • compute_exchange_coefficients computes the exchange coefficients

References

@article{nishizawa2018surface, title={A Surface Flux Scheme Based on the Monin-Obukhov Similarity for Finite Volume Models}, author={Nishizawa, S and Kitamura, Y}, journal={Journal of Advances in Modeling Earth Systems}, volume={10}, number={12}, pages={3159–3175}, year={2018}, publisher={Wiley Online Library} }

@article{byun1990analytical, title={On the analytical solutions of flux-profile relationships for the atmospheric surface layer}, author={Byun, Daewon W}, journal={Journal of Applied Meteorology}, volume={29}, number={7}, pages={652–657}, year={1990} }

compute_buoyancy_flux(param_set, shf, lhf, T_b, q, α_0)

Computes buoyancy flux given

• shf sensible heat flux
• lhf latent heat flux
• T_b surface boundary temperature
• q phase partition (see PhasePartition)
• α_0 specific volume

monin_obukhov_len(param_set, u, flux)

Computes the Monin-Obukhov length (Eq. 3)

compute_friction_velocity(param_set, flux, z_0, z_1, β_m, γ_m, tol_abs, iter_max)

Computes roots of friction velocity equation (Eq. 10)

u_ave = u_* ( ln(z/z_0) - ψ_m(z/L, z_0/L) ) /κ

compute_exchange_coefficients(param_set, Ri, z_b, z_0, γ_m, γ_h, β_m, β_h, Pr_0)

Computes exchange transfer coefficients:

• C_D momentum exchange coefficient (Eq. 36)
• C_H thermodynamic exchange coefficient (Eq. 37)
• L_mo Monin-Obukhov length (re-arranged Eq. 3)

TODO: Pr_0 should come from CLIMAParameters

monin_obukhov_len(param_set, u, θ, flux)

Computes Monin-Obukhov length. Eq. 3

compute_friction_velocity(param_set, u_ave, θ, flux, Δz, z_0, a, Ψ_m_tol, tol_abs, iter_max)

Computes friction velocity, in Eq. 12 in, by solving the non-linear equation:

u_ave = ustar/κ * ( ln(Δz/z_0) - Ψ_m(Δz/L) + z_0/Δz * Ψ_m(z_0/L) + R_z0 [ψ_m(z_0/L) - 1] )

where L is a non-linear function of ustar (see monin_obukhov_len).

compute_exchange_coefficients(param_set, z, F_m, F_h, a, u_star, θ, flux, Pr)

Computes exchange transfer coefficients:

• K_D momentum exchange coefficient
• K_H thermodynamic exchange coefficient
• L_mo Monin-Obukhov length

TODO: Pr should come from CLIMAParameters