GFS Surface Layer Module

This module calculates surface roughness length.This subroutine includes the surface roughness length formulation based on the surface sublayer scheme in Zeng and Dickinson (1998) [203]. More...

Functions/Subroutines
subroutine, public	sfc_diff::sfc_diff_run (im, rvrdm1, eps, epsm1, grav, ps, t1, q1, z1, garea, wind, prsl1, prslki, prsik1, prslk1, sigmaf, vegtype, shdmax, ivegsrc, z0pert, ztpert, flag_iter, redrag, u10m, v10m, sfc_z0_type, wet, dry, icy, thsfc_loc, tskin_wat, tskin_lnd, tskin_ice, tsurf_wat, tsurf_lnd, tsurf_ice, z0rl_wat, z0rl_lnd, z0rl_ice, z0rl_wav, ustar_wat, ustar_lnd, ustar_ice, cm_wat, cm_lnd, cm_ice, ch_wat, ch_lnd, ch_ice, rb_wat, rb_lnd, rb_ice, stress_wat, stress_lnd, stress_ice, fm_wat, fm_lnd, fm_ice, fh_wat, fh_lnd, fh_ice, fm10_wat, fm10_lnd, fm10_ice, fh2_wat, fh2_lnd, fh2_ice, ztmax_wat, ztmax_lnd, ztmax_ice, zvfun, errmsg, errflg)
subroutine, public	sfc_diff::stability (z1, zvfun, gdx, tv1, thv1, wind, z0max, ztmax, tvs, grav, thsfc_loc, rb, fm, fh, fm10, fh2, cm, ch, stress, ustar)
subroutine	sfc_diff::znot_m_v6 (uref, znotm)

Detailed Description

Argument Table

GFS Surface Layer Scheme General Algorithm

• Calculate the thermal roughness length formulation over the ocean (see eq. (25) and (26) in Zeng et al. (1998) [204]).
• Calculate Zeng's momentum roughness length formulation over land and sea ice.
• Calculate the new vegetation-dependent formulation of thermal roughness length (Zheng et al.(2012) [206]). Zheng et al. (2012) [206] proposed a new formulation on \(ln(Z_{0m}^,/Z_{0t})\) as follows:

  \[ ln(Z_{0m}^,/Z_{0t})=(1-GVF)^2C_{zil}k(u*Z_{0g}/\nu)^{0.5} \]

  where \(Z_{0m}^,\) is the effective momentum roughness length computed in the following equation for each grid, \(Z_{0t}\) is the roughness lenghth for heat, \(C_{zil}\) is a coefficient (taken as 0.8), k is the Von Karman constant (0.4), \(\nu=1.5\times10^{-5}m^{2}s^{-1}\) is the molecular viscosity, \(u*\) is the friction velocity, and \(Z_{0g}\) is the bare soil roughness length for momentum (taken as 0.01).
  In order to consider the convergence of \(Z_{0m}\) between fully vegetated and bare soil, the effective \(Z_{0m}^,\) is computed:

  \[ \ln(Z_{0m}^,)=(1-GVF)^{2}\ln(Z_{0g})+\left[1-(1-GVF)^{2}\right]\ln(Z_{0m}) \]

• Calculate the exchange coefficients: \(cm\), \(ch\), and \(stress\) as inputs of other sfc schemes.