GFS Surface Layer Scheme Module

This subroutine calculates surface roughness length. More...

Detailed Description

This subroutine includes the surface roughness length formulation based on the surface sublayer scheme in Zeng and Dickinson (1998) [187].

Argument Table

local_name	standard_name	long_name	units	type	dimensions	kind	intent	optional
im	horizontal_loop_extent	horizontal loop extent	count	integer	()		in	False
rvrdm1	ratio_of_vapor_to_dry_air_gas_constants_minus_one	(rv/rd) - 1 (rv = ideal gas constant for water vapor)	none	real	()	kind_phys	in	False
eps	ratio_of_dry_air_to_water_vapor_gas_constants	rd/rv	none	real	()	kind_phys	in	False
epsm1	ratio_of_dry_air_to_water_vapor_gas_constants_minus_one	(rd/rv) - 1	none	real	()	kind_phys	in	False
grav	gravitational_acceleration	gravitational acceleration	m s-2	real	()	kind_phys	in	False
ps	surface_air_pressure	surface pressure	Pa	real	(horizontal_dimension)	kind_phys	in	False
t1	air_temperature_at_lowest_model_layer	1st model layer air temperature	K	real	(horizontal_dimension)	kind_phys	in	False
q1	water_vapor_specific_humidity_at_lowest_model_layer	1st model layer specific humidity	kg kg-1	real	(horizontal_dimension)	kind_phys	in	False
z1	height_above_ground_at_lowest_model_layer	height above ground at 1st model layer	m	real	(horizontal_dimension)	kind_phys	in	False
wind	wind_speed_at_lowest_model_layer	wind speed at lowest model level	m s-1	real	(horizontal_dimension)	kind_phys	in	False
prsl1	air_pressure_at_lowest_model_layer	Model layer 1 mean pressure	Pa	real	(horizontal_dimension)	kind_phys	in	False
prslki	ratio_of_exner_function_between_midlayer_and_interface_at_lowest_model_layer	Exner function ratio bt midlayer and interface at 1st layer	ratio	real	(horizontal_dimension)	kind_phys	in	False
prsik1	dimensionless_exner_function_at_lowest_model_interface	dimensionless Exner function at the ground surface	none	real	(horizontal_dimension)	kind_phys	in	False
prslk1	dimensionless_exner_function_at_lowest_model_layer	dimensionless Exner function at the lowest model layer	none	real	(horizontal_dimension)	kind_phys	in	False
sigmaf	bounded_vegetation_area_fraction	areal fractional cover of green vegetation bounded on the bottom	frac	real	(horizontal_dimension)	kind_phys	in	False
vegtype	vegetation_type_classification	vegetation type at each grid cell	index	integer	(horizontal_dimension)		in	False
shdmax	maximum_vegetation_area_fraction	max fractnl cover of green veg	frac	real	(horizontal_dimension)	kind_phys	in	False
ivegsrc	vegetation_type_dataset_choice	land use dataset choice	index	integer	()		in	False
z0pert	perturbation_of_momentum_roughness_length	perturbation of momentum roughness length	frac	real	(horizontal_dimension)	kind_phys	in	False
ztpert	perturbation_of_heat_to_momentum_roughness_length_ratio	perturbation of heat to momentum roughness length ratio	frac	real	(horizontal_dimension)	kind_phys	in	False
flag_iter	flag_for_iteration	flag for iteration	flag	logical	(horizontal_dimension)		in	False
redrag	flag_for_reduced_drag_coefficient_over_sea	flag for reduced drag coefficient over sea	flag	logical	()		in	False
u10m	x_wind_at_10m	10 meter u wind speed	m s-1	real	(horizontal_dimension)	kind_phys	in	False
v10m	y_wind_at_10m	10 meter v wind speed	m s-1	real	(horizontal_dimension)	kind_phys	in	False
sfc_z0_type	flag_for_surface_roughness_option_over_ocean	surface roughness options over ocean	flag	integer	()		in	False
wet	flag_nonzero_wet_surface_fraction	flag indicating presence of some ocean or lake surface area fraction	flag	logical	(horizontal_dimension)		in	False
dry	flag_nonzero_land_surface_fraction	flag indicating presence of some land surface area fraction	flag	logical	(horizontal_dimension)		in	False
icy	flag_nonzero_sea_ice_surface_fraction	flag indicating presence of some sea ice surface area fraction	flag	logical	(horizontal_dimension)		in	False
tskin_wat	surface_skin_temperature_over_ocean_interstitial	surface skin temperature over ocean (temporary use as interstitial)	K	real	(horizontal_dimension)	kind_phys	in	False
tskin_lnd	surface_skin_temperature_over_land_interstitial	surface skin temperature over land (temporary use as interstitial)	K	real	(horizontal_dimension)	kind_phys	in	False
tskin_ice	surface_skin_temperature_over_ice_interstitial	surface skin temperature over ice (temporary use as interstitial)	K	real	(horizontal_dimension)	kind_phys	in	False
tsurf_wat	surface_skin_temperature_after_iteration_over_ocean	surface skin temperature after iteration over ocean	K	real	(horizontal_dimension)	kind_phys	in	False
tsurf_lnd	surface_skin_temperature_after_iteration_over_land	surface skin temperature after iteration over land	K	real	(horizontal_dimension)	kind_phys	in	False
tsurf_ice	surface_skin_temperature_after_iteration_over_ice	surface skin temperature after iteration over ice	K	real	(horizontal_dimension)	kind_phys	in	False
snwdph_wat	surface_snow_thickness_water_equivalent_over_ocean	water equivalent snow depth over ocean	mm	real	(horizontal_dimension)	kind_phys	in	False
snwdph_lnd	surface_snow_thickness_water_equivalent_over_land	water equivalent snow depth over land	mm	real	(horizontal_dimension)	kind_phys	in	False
snwdph_ice	surface_snow_thickness_water_equivalent_over_ice	water equivalent snow depth over ice	mm	real	(horizontal_dimension)	kind_phys	in	False
z0rl_wat	surface_roughness_length_over_ocean_interstitial	surface roughness length over ocean (temporary use as interstitial)	cm	real	(horizontal_dimension)	kind_phys	inout	False
z0rl_lnd	surface_roughness_length_over_land_interstitial	surface roughness length over land (temporary use as interstitial)	cm	real	(horizontal_dimension)	kind_phys	inout	False
z0rl_ice	surface_roughness_length_over_ice_interstitial	surface roughness length over ice (temporary use as interstitial)	cm	real	(horizontal_dimension)	kind_phys	inout	False
z0rl_wav	surface_roughness_length_from_wave_model	surface roughness length from wave model	cm	real	(horizontal_dimension)	kind_phys	in	False
ustar_wat	surface_friction_velocity_over_ocean	surface friction velocity over ocean	m s-1	real	(horizontal_dimension)	kind_phys	inout	False
ustar_lnd	surface_friction_velocity_over_land	surface friction velocity over land	m s-1	real	(horizontal_dimension)	kind_phys	inout	False
ustar_ice	surface_friction_velocity_over_ice	surface friction velocity over ice	m s-1	real	(horizontal_dimension)	kind_phys	inout	False
cm_wat	surface_drag_coefficient_for_momentum_in_air_over_ocean	surface exchange coeff for momentum over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
cm_lnd	surface_drag_coefficient_for_momentum_in_air_over_land	surface exchange coeff for momentum over land	none	real	(horizontal_dimension)	kind_phys	inout	False
cm_ice	surface_drag_coefficient_for_momentum_in_air_over_ice	surface exchange coeff for momentum over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
ch_wat	surface_drag_coefficient_for_heat_and_moisture_in_air_over_ocean	surface exchange coeff heat & moisture over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
ch_lnd	surface_drag_coefficient_for_heat_and_moisture_in_air_over_land	surface exchange coeff heat & moisture over land	none	real	(horizontal_dimension)	kind_phys	inout	False
ch_ice	surface_drag_coefficient_for_heat_and_moisture_in_air_over_ice	surface exchange coeff heat & moisture over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
rb_wat	bulk_richardson_number_at_lowest_model_level_over_ocean	bulk Richardson number at the surface over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
rb_lnd	bulk_richardson_number_at_lowest_model_level_over_land	bulk Richardson number at the surface over land	none	real	(horizontal_dimension)	kind_phys	inout	False
rb_ice	bulk_richardson_number_at_lowest_model_level_over_ice	bulk Richardson number at the surface over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
stress_wat	surface_wind_stress_over_ocean	surface wind stress over ocean	m2 s-2	real	(horizontal_dimension)	kind_phys	inout	False
stress_lnd	surface_wind_stress_over_land	surface wind stress over land	m2 s-2	real	(horizontal_dimension)	kind_phys	inout	False
stress_ice	surface_wind_stress_over_ice	surface wind stress over ice	m2 s-2	real	(horizontal_dimension)	kind_phys	inout	False
fm_wat	Monin_Obukhov_similarity_function_for_momentum_over_ocean	Monin-Obukhov similarity function for momentum over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
fm_lnd	Monin_Obukhov_similarity_function_for_momentum_over_land	Monin-Obukhov similarity function for momentum over land	none	real	(horizontal_dimension)	kind_phys	inout	False
fm_ice	Monin_Obukhov_similarity_function_for_momentum_over_ice	Monin-Obukhov similarity function for momentum over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
fh_wat	Monin_Obukhov_similarity_function_for_heat_over_ocean	Monin-Obukhov similarity function for heat over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
fh_lnd	Monin_Obukhov_similarity_function_for_heat_over_land	Monin-Obukhov similarity function for heat over land	none	real	(horizontal_dimension)	kind_phys	inout	False
fh_ice	Monin_Obukhov_similarity_function_for_heat_over_ice	Monin-Obukhov similarity function for heat over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
fm10_wat	Monin_Obukhov_similarity_function_for_momentum_at_10m_over_ocean	Monin-Obukhov similarity parameter for momentum at 10m over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
fm10_lnd	Monin_Obukhov_similarity_function_for_momentum_at_10m_over_land	Monin-Obukhov similarity parameter for momentum at 10m over land	none	real	(horizontal_dimension)	kind_phys	inout	False
fm10_ice	Monin_Obukhov_similarity_function_for_momentum_at_10m_over_ice	Monin-Obukhov similarity parameter for momentum at 10m over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
fh2_wat	Monin_Obukhov_similarity_function_for_heat_at_2m_over_ocean	Monin-Obukhov similarity parameter for heat at 2m over ocean	none	real	(horizontal_dimension)	kind_phys	inout	False
fh2_lnd	Monin_Obukhov_similarity_function_for_heat_at_2m_over_land	Monin-Obukhov similarity parameter for heat at 2m over land	none	real	(horizontal_dimension)	kind_phys	inout	False
fh2_ice	Monin_Obukhov_similarity_function_for_heat_at_2m_over_ice	Monin-Obukhov similarity parameter for heat at 2m over ice	none	real	(horizontal_dimension)	kind_phys	inout	False
errmsg	ccpp_error_message	error message for error handling in CCPP	none	character	()	len=*	out	False
errflg	ccpp_error_flag	error flag for error handling in CCPP	flag	integer	()		out	False

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) [188]).
• 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.(2009) [190]). Zheng et al. (2009) [190] 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.

Functions/Subroutines
subroutine, public	sfc_diff::sfc_diff_run (im, rvrdm1, eps, epsm1, grav, ps, t1, q1, z1, wind, prsl1, prslki, prsik1, prslk1, sigmaf, vegtype, shdmax, ivegsrc, z0pert, ztpert, flag_iter, redrag, u10m, v10m, sfc_z0_type, wet, dry, icy, tskin_wat, tskin_lnd, tskin_ice, tsurf_wat, tsurf_lnd, tsurf_ice, snwdph_wat, snwdph_lnd, snwdph_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, errmsg, errflg)
subroutine	sfc_diff::stability