GFS Three-layer Thermodynomics Sea-Ice Scheme Module

This is three-layer thermodynomics sea-ice model based on Winton (2000) [178]. More...

Detailed Description

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
kice	ice_vertical_dimension	vertical loop extent for ice levels, start at 1	count	integer	()		in	False
sbc	stefan_boltzmann_constant	Stefan-Boltzmann constant	W m-2 K-4	real	()	kind_phys	in	False
hvap	latent_heat_of_vaporization_of_water_at_0C	latent heat of evaporation/sublimation	J kg-1	real	()	kind_phys	in	False
tgice	freezing_point_temperature_of_seawater	freezing point temperature of seawater	K	real	()	kind_phys	in	False
cp	specific_heat_of_dry_air_at_constant_pressure	specific heat of dry air at constant pressure	J kg-1 K-1	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
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
grav	gravitational_acceleration	gravitational acceleration	m s-2	real	()	kind_phys	in	False
t0c	temperature_at_zero_celsius	temperature at 0 degree Celsius	K	real	()	kind_phys	in	False
rd	gas_constant_dry_air	ideal gas constant for dry air	J kg-1 K-1	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	surface layer mean temperature	K	real	(horizontal_dimension)	kind_phys	in	False
q1	water_vapor_specific_humidity_at_lowest_model_layer	surface layer mean specific humidity	kg kg-1	real	(horizontal_dimension)	kind_phys	in	False
delt	time_step_for_dynamics	time step	s	real	()	kind_phys	in	False
sfcemis	surface_longwave_emissivity_over_ice_interstitial	surface lw emissivity in fraction over ice (temporary use as interstitial)	frac	real	(horizontal_dimension)	kind_phys	in	False
dlwflx	surface_downwelling_longwave_flux_absorbed_by_ground_over_ice	total sky surface downward longwave flux absorbed by the ground over ice	W m-2	real	(horizontal_dimension)	kind_phys	in	False
sfcnsw	surface_net_downwelling_shortwave_flux	total sky sfc netsw flx into ground	W m-2	real	(horizontal_dimension)	kind_phys	in	False
sfcdsw	surface_downwelling_shortwave_flux	total sky sfc downward sw flux	W m-2	real	(horizontal_dimension)	kind_phys	in	False
srflag	flag_for_precipitation_type	snow/rain flag for precipitation	flag	real	(horizontal_dimension)	kind_phys	in	False
cm	surface_drag_coefficient_for_momentum_in_air_over_ice	surface exchange coeff for momentum over ice	none	real	(horizontal_dimension)	kind_phys	in	False
ch	surface_drag_coefficient_for_heat_and_moisture_in_air_over_ice	surface exchange coeff heat & moisture over ice	none	real	(horizontal_dimension)	kind_phys	in	False
prsl1	air_pressure_at_lowest_model_layer	surface layer 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
wind	wind_speed_at_lowest_model_layer	wind speed at lowest model level	m s-1	real	(horizontal_dimension)	kind_phys	in	False
flag_iter	flag_for_iteration	flag for iteration	flag	logical	(horizontal_dimension)		in	False
lprnt	flag_print	switch for printing sample column to stdout	flag	logical	()		in	False
ipr	horizontal_index_of_printed_column	horizontal index of printed column	index	integer	()		in	False
hice	sea_ice_thickness	sea-ice thickness	m	real	(horizontal_dimension)	kind_phys	inout	False
fice	sea_ice_concentration	sea-ice concentration [0,1]	frac	real	(horizontal_dimension)	kind_phys	inout	False
tice	sea_ice_temperature_interstitial	sea-ice surface temperature use as interstitial	K	real	(horizontal_dimension)	kind_phys	inout	False
weasd	water_equivalent_accumulated_snow_depth_over_ice	water equiv of acc snow depth over ice	mm	real	(horizontal_dimension)	kind_phys	inout	False
tskin	surface_skin_temperature_over_ice_interstitial	surface skin temperature over ice (temporary use as interstitial)	K	real	(horizontal_dimension)	kind_phys	inout	False
tprcp	nonnegative_lwe_thickness_of_precipitation_amount_on_dynamics_timestep_over_ice	total precipitation amount in each time step over ice	m	real	(horizontal_dimension)	kind_phys	inout	False
tiice	internal_ice_temperature	sea ice internal temperature	K	real	(horizontal_dimension, ice_vertical_dimension)	kind_phys	inout	False
ep	surface_upward_potential_latent_heat_flux_over_ice	surface upward potential latent heat flux over ice	W m-2	real	(horizontal_dimension)	kind_phys	inout	False
snwdph	surface_snow_thickness_water_equivalent_over_ice	water equivalent snow depth over ice	mm	real	(horizontal_dimension)	kind_phys	inout	False
qsurf	surface_specific_humidity_over_ice	surface air saturation specific humidity over ice	kg kg-1	real	(horizontal_dimension)	kind_phys	inout	False
snowmt	surface_snow_melt	snow melt during timestep	m	real	(horizontal_dimension)	kind_phys	inout	False
gflux	upward_heat_flux_in_soil_over_ice	soil heat flux over ice	W m-2	real	(horizontal_dimension)	kind_phys	inout	False
cmm	surface_drag_wind_speed_for_momentum_in_air_over_ice	momentum exchange coefficient over ice	m s-1	real	(horizontal_dimension)	kind_phys	inout	False
chh	surface_drag_mass_flux_for_heat_and_moisture_in_air_over_ice	thermal exchange coefficient over ice	kg m-2 s-1	real	(horizontal_dimension)	kind_phys	inout	False
evap	kinematic_surface_upward_latent_heat_flux_over_ice	kinematic surface upward latent heat flux over ice	kg kg-1 m s-1	real	(horizontal_dimension)	kind_phys	inout	False
hflx	kinematic_surface_upward_sensible_heat_flux_over_ice	kinematic surface upward sensible heat flux over ice	K m s-1	real	(horizontal_dimension)	kind_phys	inout	False
frac_grid	flag_for_fractional_grid	flag for fractional grid	flag	logical	()		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
islmsk_cice	sea_land_ice_mask_cice	sea/land/ice mask cice (=0/1/2)	flag	integer	(horizontal_dimension)		in	False
min_lakeice	lake_ice_minimum	minimum lake ice value	frac	real	()	kind_phys	in	False
min_seaice	sea_ice_minimum	minimum sea ice value	frac	real	()	kind_phys	in	False
oceanfrac	sea_area_fraction	fraction of horizontal grid area occupied by ocean	frac	real	(horizontal_dimension)	kind_phys	in	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 Sea Ice Driver General Algorithm

The model has four prognostic variables: the snow layer thickness \(h_s\), the ice layer thickness \(h_i\), the upper and lower ice layer temperatures located at the midpoints of the layers \(h_i/4\) and \(3h_i/4\) below the ice surface, respectively \(T_1\) and \(T_2\). The temperature of the bottom of the ice is fixed at \(T_f\), the freezing temperature of seawater. The temperature of the top of the ice or snow, \(T_s\), is determined from the surface energy balance. The model consists of a zero-heat-capacity snow layer overlying two equally thick sea ice layers (Figure 1). The upper ice layer has a variable heat capacity to represent brine pockets.

Fig.1 Schematic representation of the three-layer model

The ice model main program ice3lay() performs two functions:

• Calculation of ice temperature
  The surface temperature is determined from the diagnostic balance between the upward conduction of heat through snow and/or ice and upward flux of heat from the surface.
• Calculation of ice and snow changes
  In addition to calculating ice temperature changes, the ice model must also readjust the sizes of the snow and ice layers 1) to accommodate mass fluxes at the upper and lower surfaces, 2) to convert snow below the water line to ice, and 3) to equalize the thickness of the two ice layers.

GFS Sea Ice Driver Detailed Algorithm

Functions/Subroutines
subroutine	sfc_sice::sfc_sice_run (im, kice, sbc, hvap, tgice, cp, eps, epsm1, rvrdm1, grav, t0c, rd, ps, t1, q1, delt, sfcemis, dlwflx, sfcnsw, sfcdsw, srflag, cm, ch, prsl1, prslki, prsik1, prslk1, wind, flag_iter, lprnt, ipr, hice, fice, tice, weasd, tskin, tprcp, tiice, ep, snwdph, qsurf, snowmt, gflux, cmm, chh, evap, hflx, frac_grid, icy, islmsk_cice, min_lakeice, min_seaice, oceanfrac, errmsg, errflg
subroutine	ice3lay
	This subroutine is the entity of three-layer sea ice vertical thermodynamics based on Winton(2000) [178] . More...