Holtslag-Boville-1993

Parameterized atmospheric-boundary-layer surface fluxes following Holtslag & Boville (1993), 'Local Versus Nonlocal Boundary-Layer Diffusion in a Global Climate Model', J. Climate 6, 1825-1842. A diagnostic (purely algebraic) bulk-aerodynamic scheme: from the lowest-model-level wind (u₁, v₁), the surface and lowest-level potential and virtual potential temperatures (θ₀/θ₁, θᵥ₀/θᵥ₁), and specific humidities (q₀, q₁), it computes the kinematic surface fluxes of momentum (wu₀, wv₀; Eqs. 2.1-2.2), heat (wθ₀; Eq. 2.3) and moisture (wq₀; Eq. 2.4). The stability-dependent exchange coefficients Cₘ and Cₕ (Eqs. 2.5-2.6) are the neutral coefficient Cₙ (Eq. 2.7, a logarithmic function of the roughness ratio) modulated by the stability functions fₘ and fₕ, which switch on the sign of the surface bulk Richardson number Ri₀ (Eq. 2.8): the unstable branch uses the Louis et al. (1982) forms (Eqs. 2.9-2.10) and the stable branch the Holtslag & Beljaars (1989) form (Eq. 2.11). The model has 11 algebraic variables (no time integration), 11 equations, and 15 parameters (4 physical constants + 11 inputs). All quantities are SI. Migrated from AtmosphericDynamics.jl@816cc391 src/holtslag_boville_1993.jl:35 (`HoltslagBovilleSurfaceFlux` @component).