This is three-layer thermodynomics sea-ice model based on [84]. More...

Detailed Description

Argument Table

local_name	standard_name	long_name	units	rank	type	kind	intent	optional
im	horizontal_loop_extent	horizontal loop extent	count	0	integer		in	F
km	soil_vertical_dimension	vertical loop extent for soil levels, start at 1	count	0	integer		in	F
ps	surface_air_pressure	surface pressure	Pa	1	real	kind_phys	in	F
u1	x_wind_at_lowest_model_layer	u component of surface layer wind	m s-1	1	real	kind_phys	in	F
v1	y_wind_at_lowest_model_layer	v component of surface layer wind	m s-1	1	real	kind_phys	in	F
t1	air_temperature_at_lowest_model_layer	surface layer mean temperature	K	1	real	kind_phys	in	F
q1	specific_humidity_at_lowest_model_layer	surface layer mean specific humidity	kg kg-1	1	real	kind_phys	in	F
delt	time_step_for_dynamics	time step	s	0	real	kind_phys	in	F
sfcemis	surface_longwave_emissivity	sfc lw emissivity	frac	1	real	kind_phys	in	F
dlwflx	surface_downwelling_longwave_flux_absorbed_by_ground	total sky surface downward longwave flux absorbed by the ground	W m-2	1	real	kind_phys	in	F
sfcnsw	surface_net_downwelling_shortwave_flux	total sky sfc netsw flx into ground	W m-2	1	real	kind_phys	in	F
sfcdsw	surface_downwelling_shortwave_flux	total sky sfc downward sw flux	W m-2	1	real	kind_phys	in	F
srflag	flag_for_precipitation_type	snow/rain flag for precipitation	flag	1	real	kind_phys	in	F
cm	surface_drag_coefficient_for_momentum_in_air	surface exchange coeff for momentum	none	1	real	kind_phys	in	F
ch	surface_drag_coefficient_for_heat_and_moisture_in_air	surface exchange coeff heat & moisture	none	1	real	kind_phys	in	F
prsl1	air_pressure_at_lowest_model_layer	surface layer mean pressure	Pa	1	real	kind_phys	in	F
prslki	ratio_of_exner_function_between_midlayer_and_interface_at_lowest_model_layer	Exner function ratio bt midlayer and interface at 1st layer	ratio	1	real	kind_phys	in	F
islimsk	sea_land_ice_mask	sea/land/ice mask (=0/1/2)	flag	1	integer		in	F
ddvel	surface_wind_enhancement_due_to_convection	wind enhancement due to convection	m s-1	1	real	kind_phys	in	F
flag_iter	flag_for_iteration	flag for iteration	flag	1	logical		in	F
mom4ice	flag_for_mom4_coupling	flag for Mom4 coupling	flag	0	logical		in	F
lsm	flag_for_land_surface_scheme	flag for land sfc scheme =0: osu; =1: noah	flag	0	integer		in	F
lprnt	flag_print	switch for printing sample column to stdout	flag	0	logical		in	F
ipr	horizontal_index_of_printed_column	horizontal index of printed column	index	0	integer		in	F
hice	sea_ice_thickness_for_physics	sea-ice thickness	m	1	real	kind_phys	inout	F
fice	sea_ice_concentration_for_physics	sea-ice concentration [0,1]	frac	1	real	kind_phys	inout	F
tice	sea_ice_temperature_for_physics	sea-ice surface temperature	K	1	real	kind_phys	inout	F
weasd	water_equivalent_accumulated_snow_depth	water equivalent accumulated snow depth	mm	1	real	kind_phys	inout	F
tskin	surface_skin_temperature	ground surface skin temperature	K	1	real	kind_phys	inout	F
tprcp	nonnegative_lwe_thickness_of_precipitation_amount_on_dynamics_timestep	nonnegative precipitation amount in one dynamics time step	m	1	real	kind_phys	inout	F
stc	soil_temperature	soil temp	K	2	real	kind_phys	inout	F
ep	surface_upward_potential_latent_heat_flux	potential evaporation	W m-2	1	real	kind_phys	inout	F
snwdph	surface_snow_thickness_water_equivalent	water equivalent snow depth	mm	1	real	kind_phys	inout	F
qsurf	surface_specific_humidity	sfc air saturation specific humidity	kg kg-1	1	real	kind_phys	inout	F
snowmt	surface_snow_melt	snow melt during timestep	m	1	real	kind_phys	inout	F
gflux	upward_heat_flux_in_soil	soil heat flux	W m-2	1	real	kind_phys	inout	F
cmm	surface_drag_wind_speed_for_momentum_in_air	surf mom exch coef time mean surf wind	m s-1	1	real	kind_phys	inout	F
chh	surface_drag_mass_flux_for_heat_and_moisture_in_air	surf h&m exch coef time surf wind & density	kg m-2 s-1	1	real	kind_phys	inout	F
evap	kinematic_surface_upward_latent_heat_flux	evaporative latent heat flux	kg kg-1 m s-1	1	real	kind_phys	inout	F
hflx	kinematic_surface_upward_sensible_heat_flux	kinematic sensible heat flux	K m s-1	1	real	kind_phys	inout	F
errmsg	error_message	error message for error handling in CCPP	none	0	character	len=*	out	F
errflg	error_flag	error flag for error handling in CCPP	flag	0	integer		out	F

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.

Detailed Algorithm

Functions/Subroutines
subroutine	sfc_sice::sfc_sice_run (im, km, ps, u1, v1, t1, q1, delt, sfcemis, dlwflx, sfcnsw, sfcdsw, srflag, cm, ch, prsl1, prslki, islimsk, ddvel, flag_iter, mom4ice, lsm, lprnt, ipr, hice, fice, tice, weasd, tskin, tprcp, stc, ep, snwdph, qsurf, snowmt, gflux, cmm, chh, evap, hflx, errmsg, errflg

subroutine	ice3lay
	This subroutine is the entity of three-layer sea ice vertical thermodynamics based on [84] . More...

Function/Subroutine Documentation

subroutine sfc_sice_run::ice3lay ( )

Three-layer Thermodynamics Sea Ice Model General Algorithm

Ice temperature calculation.
- Calculate the effective conductive coupling of the snow-ice layer between the surface and the upper layer ice temperature \(h_i/4\) beneath the snow-ice interface (see eq.(5) in [84]).
- Calculate the conductive coupling between the two ice temperature points (see eq.(10) in [84]).
- Calculate the new upper ice temperature following eq.(21) in [84].
- If the surface temperature is greater than the freezing temperature of snow (when there is snow over) or sea ice (when there is none), the surface temperature is fixed at the melting temperature of snow or sea ice, respectively, and the upper ice temperature is recomputed from eq.(21) using the coefficients given by eqs. (19),(20), and (18). An energy flux eq.(22) is applied toward surface melting thereby balancing the surface energy budget.
- Calculate the new lower ice temperature following eq.(15) in [84].
- Calculate the energy for bottom melting (or freezing, if negative) following eq.(23), which serves to balance the difference between the oceanic heat flux to the ice bottom and the conductive flux of heat upward from the bottom.
Calculation of ice and snow mass changes.
- Calculate the top layer thickness.
- When the energy for bottem melting \(M_b\) is negative (i.e., freezing is happening),calculate the bottom layer thickness \(h_2\) and the new lower layer temperature (see eqs.(24)-(26)).
- If ice remains, even up 2 layers, else, pass negative energy back in snow. Calculate the new upper layer temperature (see eq.(38)).

Referenced by sfc_sice::sfc_sice_run().

subroutine sfc_sice::sfc_sice_run	(	integer, intent(in)	im,
		integer, intent(in)	km,
		real (kind=kind_phys), dimension(im), intent(in)	ps,
		real (kind=kind_phys), dimension(im), intent(in)	u1,
		real (kind=kind_phys), dimension(im), intent(in)	v1,
		real (kind=kind_phys), dimension(im), intent(in)	t1,
		real (kind=kind_phys), dimension(im), intent(in)	q1,
		real (kind=kind_phys), intent(in)	delt,
		real (kind=kind_phys), dimension(im), intent(in)	sfcemis,
		real (kind=kind_phys), dimension(im), intent(in)	dlwflx,
		real (kind=kind_phys), dimension(im), intent(in)	sfcnsw,
		real (kind=kind_phys), dimension(im), intent(in)	sfcdsw,
		real (kind=kind_phys), dimension(im), intent(in)	srflag,
		real (kind=kind_phys), dimension(im), intent(in)	cm,
		real (kind=kind_phys), dimension(im), intent(in)	ch,
		real (kind=kind_phys), dimension(im), intent(in)	prsl1,
		real (kind=kind_phys), dimension(im), intent(in)	prslki,
		integer, dimension(im), intent(in)	islimsk,
		real (kind=kind_phys), dimension(im), intent(in)	ddvel,
		logical, dimension(im), intent(in)	flag_iter,
		logical, intent(in)	mom4ice,
		integer, intent(in)	lsm,
		logical, intent(in)	lprnt,
		integer, intent(in)	ipr,
		real (kind=kind_phys), dimension(im), intent(inout)	hice,
		real (kind=kind_phys), dimension(im), intent(inout)	fice,
		real (kind=kind_phys), dimension(im), intent(inout)	tice,
		real (kind=kind_phys), dimension(im), intent(inout)	weasd,
		real (kind=kind_phys), dimension(im), intent(inout)	tskin,
		real (kind=kind_phys), dimension(im), intent(inout)	tprcp,
		real (kind=kind_phys), dimension(im,km), intent(inout)	stc,
		real (kind=kind_phys), dimension(im), intent(inout)	ep,
		real (kind=kind_phys), dimension(im), intent(inout)	snwdph,
		real (kind=kind_phys), dimension(im), intent(inout)	qsurf,
		real (kind=kind_phys), dimension(im), intent(inout)	snowmt,
		real (kind=kind_phys), dimension(im), intent(inout)	gflux,
		real (kind=kind_phys), dimension(im), intent(inout)	cmm,
		real (kind=kind_phys), dimension(im), intent(inout)	chh,
		real (kind=kind_phys), dimension(im), intent(inout)	evap,
		real (kind=kind_phys), dimension(im), intent(inout)	hflx,
		character(len=*), intent(out)	errmsg,
		integer, intent(out)	errflg
	)

Set flag for sea-ice.
Update/read sea ice temperature from soil temperature and initialize variables.
Convert snow depth in water equivalent from mm to m unit.
Calculate sensible and latent heat flux over open water & sea ice.
Calculate net solar incoming at top sneti.
Calculate net non-solar and upir heat flux @ ice surface hfi.
Calculate heat flux derivative at surface hfd.
Assigin heat flux from ocean focn and snowfall rate as constants, which should be from ocean model and other physics.
Initialize snow depth snowd.
Call the three-layer thermodynamics sea ice model ice3lay().

References ice3lay().