Initialization (myTime .EQ. startTime in MITgcm) ===> Ocean Sends/ Ice Receives (fields that are sent only once) deltatimestep 1 Real*8 TimeIntervalTag grid dimensions (Nx,Ny) 2 Integer OceanGridsizeTag xC Nx*Ny Real*8 xCtag yC Nx*Ny Real*8 yCtag xG Nx*Ny Real*8 xGtag yG Nx*Ny Real*8 yGtag dxG Nx*Ny Real*8 dxGtag dyG Nx*Ny Real*8 dxGtag AngleCS Nx*Ny Real*8 aCStag AngleSN Nx*Ny Real*8 aSNtag hFacC Nx*Ny Real*8 hFacCtag ice area Nx*Ny Real*8 AreaTag ice thickness Nx*Ny Real*8 HeffTag ice salinity Nx*Ny Real*8 HsaltTag snow thickness Nx*Ny Real*8 HsnowTag ===================================== Each deltatimestep: ===> Ocean Sends/Ice Receives ocean model time 1 Real*8 OceanTimeTag boundary ice area 2*(Nx+Ny)-4 Real*8 AreaBcTag boundary ice thickness 2*(Nx+Ny)-4 Real*8 HeffBcTag boundary ice salinity 2*(Nx+Ny)-4 Real*8 HsaltBcTag boundary snow thickness 2*(Nx+Ny)-4 Real*8 HsnowBcTag boundary u ice 2*(Nx+Ny)-6 Real*8 UiceBcTag boundary v ice 2*(Nx+Ny)-6 Real*8 ViceBcTag u-wind velocity Nx*Ny Real*8 UwindTag v-wind velocity Nx*Ny Real*8 VwindTag downward longwave radiation Nx*Ny Real*8 LwDownTag downward shortwave radiation Nx*Ny Real*8 SwDownTag air temperature Nx*Ny Real*8 AtempTag humidity Nx*Ny Real*8 AqhTag precipitation Nx*Ny Real*8 PrecipTag ocean surface temperature Nx*Ny Real*8 SstTag ocean surface salinity Nx*Ny Real*8 SssTag surface u current Nx*Ny Real*8 UvelTag surface v current Nx*Ny Real*8 VvelTag ===> Ice Sends/Ocean Receives ice model time 1 Real*8 IceTimeTag ice area Nx*Ny Real*8 AreaTag ice thickness Nx*Ny Real*8 HeffTag ice salinity Nx*Ny Real*8 HsaltTag snow thickness Nx*Ny Real*8 HsnowTag u ice velocity Nx*Ny Real*8 UiceTag v ice velocity Nx*Ny Real*8 ViceTag u surface stress Nx*Ny Real*8 UstressTag v surface stress Nx*Ny Real*8 VstressTag residual shortwave Nx*Ny Real*8 SwResidTag heat flux Nx*Ny Real*8 HeatFluxTag freshwater flux Nx*Ny Real*8 WaterFluxTag salt flux Nx*Ny Real*8 SaltFluxTag ===================================== DETAILS: 1. start and initialize ocean + ice codes =========================================================== 2. ocean sends **** initial time step only ******************************* deltatimestep 1 Real*8 TimeIntervalTag grid dimensions (Nx,Ny) 2 Integer OceanGridsizeTag Some grid information - see MITgcm/model/inc/GRID.h for details: xC :: longitude East of center of grid cell yC ::latitude North of center of grid cell xG :: longitude East of SouthWest corner yG :: latitude North of SouthWest corner dxG :: distance in m between SouthWest and SouthEast corner dyG :: distance in m between SouthWest and NorthEast corner aCS :: cosine(alpha) relative to geographic direction at grid cell center aSN :: sine(alpha) relative to geographic direction at grid cell center alpha = angle of model uVel direction vs geographical East = angle of model vVel direction vs geographical North (AngleCS*uVelc - AngleSN*vVelc, AngleSN*uVelc + AngleCN*vVelc) rotates model velocity to geographical coordinates, where (uVelc,vVelc) is model velocity vector at center of grid cell Then on tracer grid: hFacC :: landmask of center of grid cell, 0 is land, >0 is ocean initial ice area (fractional: 0-1) at the tracer points C AREA - fractional ice-covered area in m^2/m^2 C at center of grid, i.e., tracer point C 0 is no cover, 1 is 100% cover initial ice thickness (mean thickness in the grid box in m) actual thickness for single-class ice would be thickness/area at the tracer points C HEFF - effective ice thickness in m C at center of grid, i.e., tracer point C note: for non-zero AREA, actual ice C thickness is HEFF / AREA initial ice salinity at the tracer points C HSALT - effective sea ice salinity in g/m^2 C at center of grid, i.e., tracer point initial snow thickness (mean thickness, m) at the tracer points C HSNOW - effective snow thickness in m C at center of grid, i.e., tracer point C note: for non-zero AREA, actual snow C thickness is HSNOW / AREA **** every time step ************************************** ocean model time "myTime" (s) boundary ice area 2*(Nx+Ny)-4 Real*8 AreaBcTag boundary ice thickness 2*(Nx+Ny)-4 Real*8 HeffBcTag boundary ice salinity 2*(Nx+Ny)-4 Real*8 HsaltBcTag boundary snow thickness 2*(Nx+Ny)-4 Real*8 HsnowBcTag open boundary u-ice velocity specified at the inside edge of the outer grid cells southwest C-grid locations for normal component and at the southwest C-grid locations for tangential C UICE - zonal ice velocity in m/s at South-West C-grid U point C >0 from West to East open boundary v-ice velocity specified at the inside edge of the outer grid cells southwest C-grid locations for normal component and at the southwest C-grid locations for tangential C VICE - meridional ice velocity in m/s at South-West C-grid V point C >0 from South to North 10-m u-wind at the tracer points c uwind :: Surface (10-m) zonal wind velocity in m/s c > 0 for increase in uVel, which is west to c east for cartesian and spherical polar grids c Typical range: -10 < uwind < 10 c Input or input/output field 10-m v-wind at the tracer points c vwind :: Surface (10-m) meridional wind velocity in m/s c > 0 for increase in vVel, which is south to c north for cartesian and spherical polar grids c Typical range: -10 < vwind < 10 c Input or input/output field downward longwave at the tracer points c lwdown :: Downward longwave radiation in W/m^2 c > 0 for increase in theta (ocean warming) c Typical range: 50 < lwdown < 450 c Input/output field downward shortwave at the tracer points c swdown :: Downward shortwave radiation in W/m^2 c > 0 for increase in theta (ocean warming) c Typical range: 0 < swdown < 450 c Input/output field 2-m air temperature at the tracer points c atemp :: Surface (2-m) air temperature in deg K c Typical range: 200 < atemp < 300 c Input or input/output field 2-m humidity at the tracer points c aqh :: Surface (2m) specific humidity in kg/kg c Typical range: 0 < aqh < 0.02 c Input or input/output field precipitation at the tracer points c precip :: Precipitation in m/s c > 0 for decrease in salt (ocean salinity) c Typical range: 0 < precip < 5e-7 c Input or input/output field sea surface temperature at the tracer points C theta - potential temperature (oC, held at pressure/tracer point) sea surface u-vel C uVel - zonal velocity (m/s, i=1 held at western face) at southwest c-grid locations sea surface v-vel C vVel - meridional velocity (m/s, j=1 held at southern face) at southwest c-grid locations =========================================================== 3. ice receives 2., computes initial ice conditions and sends on tracer grid ice model time (s) ice area at tracer point C AREA :: fractional ice-covered area in m^2/m^2 C at center of grid, i.e., tracer point C 0 is no cover, 1 is 100% cover ice thickness at tracer point C HEFF :: effective ice thickness in m C at center of grid, i.e., tracer point C note: for non-zero AREA, C actual ice thickness is HEFF / AREA ice salinity at tracer point C HSALT :: effective sea ice salinity in g/m^2 C at center of grid, i.e., tracer point snow thickness at tracer point C HSNOW :: effective snow thickness in m C at center of grid, i.e., tracer point C note: for non-zero AREA, actual snow thickness is HSNOW / AREA u ice velocity at southwest c-grid locations C UICE - zonal ice velocity in m/s at South-West C-grid U point C >0 from West to East v ice velocity at southwest c-grid locations C VICE - meridional ice velocity in m/s at South-West C-grid V point C >0 from South to North u-stress under ice at southwest c-grid locations C fu :: Zonal surface wind stress in N/m^2 C > 0 for increase in uVel, which is west to C east for cartesian and spherical polar grids C Typical range: -0.5 < fu < 0.5 C Southwest C-grid U point v-stress under ice at southwest c-grid locations C fv :: Meridional surface wind stress in N/m^2 C > 0 for increase in vVel, which is south to C north for cartesian and spherical polar grids C Typical range: -0.5 < fv < 0.5 C Southwest C-grid V point residual shortwave under ice at tracer point C Qsw :: Net upward shortwave radiation in W/m^2 C Qsw = - ( downward - ice and snow absorption - reflected ) C > 0 for decrease in theta (ocean cooling) C Typical range: -350 < Qsw < 0 C Southwest C-grid tracer point heat flux (less shortwave) at tracer point C HeatFlux C :: Upward surface heat flux (excluding shortwave) in W/m^2 C HeatFlux = latent + sensible + net longwave C > 0 for decrease in theta (ocean cooling) C Typical range: -250 < HeatFlux < 950 C Southwest C-grid tracer point freshwater flux at tracer point C EmPmR :: Net upward freshwater flux in kg/m2/s C EmPmR = Evaporation - precipitation - runoff C > 0 for increase in salt (ocean salinity) C Typical range: -1e-4 < EmPmR < 1e-4 C Southwest C-grid tracer point C NOTE: for backward compatibility EmPmRfile is specified in C m/s when using external_fields_load.F. It is converted C to kg/m2/s by multiplying by rhoConstFresh. salt flux at tracer point C saltFlux :: Net upward salt flux in psu.kg/m^2/s C flux of Salt taken out of the ocean per time unit (second). C Note: a) only used when salty sea-ice forms or melts. C b) units: when salinity (unit= psu) is expressed C in g/kg, saltFlux unit becomes g/m^2/s. C > 0 for decrease in SSS. C Southwest C-grid tracer point =========================================================== 4a. ice model steps forward by deltatimestep initially hardwired to 20 minutes 4b. ocean model receives 3. and steps forward by deltatimestep initially hardwired to 20 minutes =========================================================== 5a. ocean sends on tracer grid timestep open boundary ice area at tracer point open boundary ice thickness at tracer point open boundary snow thickness at tracer point open boundary ice salinity at tracer point open boundary u-ice velocity (see 2.) open boundary v-ice velocity (see 2.) 10-m u-wind (see 2.) 10-m v-wind (see 2.) downward longwave (see 2.) downward shortwave (see 2.) 2-m air temperature (see 2.) 2-m humidity (see 2.) precipitation (see 2.) sea surface temperature (see 2.) sea surface u-vel (see 2.) sea surface v-vel (see 2.) =========================================================== 5b. ice sends on tracer grid ice model time (s) ice area at tracer point ice thickness at tracer point ice salinity at tracer point snow thickness at tracer point u-stress under ice at southwest b-grid locations v-stress under ice at southwest b-grid locations residual shortwave under ice at tracer point heat flux (less shortwave) at tracer point freshwater flux at tracer point salt flux at tracer point =========================================================== 6a. ocean model receives 5b. and steps forward by deltatimestep initially hardwired to 20 minutes 6b. ice model receives 5a. steps forward by deltatimestep initially hardwired to 20 minutes =========================================================== LOOP to 5a. and 5b.