Conservation quantities and calculations: This document explains the identities that should be observed in the model as a check of water mass, energy and salt conservation. Note that these identities may be affected by round-off errors in the PRT tables. Also, due to the 5 hour default timestep for the radiation, the average radiation diagnostics will not be exact unless the number of hours run is divisible by 5 (=NRAD). Similarly, conservation quantities may not be exact unless nda5s and nda5d are set to 1 (accumulation at every time step). First side of equations come from "Conservation Quantities". Second side of equations come from "Budgets". The budget quantities sometimes need to be scaled by the fractional area for each particular type: OOfrac = open ocean fraction (~ 0.65) OIfrac = ocean ice fraction (~ 0.04) OCfrac = ocean fraction (~ 0.70) LKOfrac = open lake fraction (~ 0.002) LKIfrac = lake ice fraction (~ 0.003) LKfrac = lake fraction (~ 0.006) LIfrac = land ice fraction (~ 0.03) GRfrac = ground/earth fraction (~ 0.25) These fractions will depend on the land mask and climate and so must be checked against the "SURF TYPE FRAC" diagnostic. Conservation of Salt -------------------- Ocean Ice salt: SUM OF CHANGES OF OICE SLT (10^-12 kg/s/m^2) = Oceans: [Salt Run + Salt Melt] * OOfrac / 0.0000864 For coupled models: Ocean Ice salt: SUM OF CHANGES OF OICE SLT (10^-12 kg/s/m^2) = Ocean salt: SUM OF CHANGES OF OCN SALT (10^-9 kg/s/m^2) * 0.001 Conservation of Water mass fluxes --------------------------------- 0 = Global: [RIVER DISCH - DWN IMP WT FLX] Excess river discharge is due to parameterisation of iceberg calving of excess water from ice sheet accumulation. 0 = Global: WATER RUNOFF Conservation of Water Vapor in Atmosphere ----------------------------------------- Atmosphere: Change of ATM WAT by DYNAMICS (10^-8 kg/s*m^2) = 0 Atmosphere: Change of ATM WAT by CONDENSATN (10^-8 kg/s*m^2) = Global: - [Precip] / .000864 Atmosphere: Change of ATM WAT by SURFACE (10^-8 kg/s*m^2) = Global: - [Evapor] / .000864 Conservation of Water in Ground ------------------------------- Ground: Change of GRND WAT by EARTH (10^-9 kg/s*m^2) = LAND: [Precip - Evap - Water Runoff - Dwn Imp] * GRfrac / .0000864 Implicit flux accounts for excess snow accumulation correction. Conservation of Glacial Ice --------------------------- LAND ICE: SUM OF CHANGES (10**-9 KG/SM^2) = Glacial Ic: [Precip - Evap - Water Runoff - Dwn Imp] * LIfrac / .0000864 Conservation of Ice over OCEANS and LAKES ----------------------------------------- For either Ocean or Lake ice: Ice: SUM CHANGES OF ICE MASS (10^-9 kg/s*m^2) = ( Ice covered: [Precip - Evap] * - total Oceans/Lakes: [Ice Melt + Dwn Impl Wt Flx] * ) / 0.0000864 Ocean Ice: CHANGE OF OICE MASS BY ADVECT (10^-8 kg/s*m^2) = 0 Conservation of Water in Lakes ------------------------------ Note: lake variables are in in J/m^2, kg/^2 over the whole globe. Lakes: Change of LAK MASS by RIVERS (10^-9 kg/s/m^2) * 0.0000864 = Lakes: [Rvr Disch] * LKfrac = - Oceans: [Rvr Disch] * OCfrac Lakes: SUM Changes of LAK MASS (10^-9 kg/s/m^2) * 0.0000864 = ( Open Lake: [Precip - Evap] * LKOfrac + Lakes: [-Water Runoff + Ice Melt + Rvr Disch] * LKfrac ) Conservation of Liquid Ocean Mass (coupled models) -------------------------------------------------- 1) Qflux model: Ocean: [Precip + Rvr Disch - Evap - Dwn Imp] = 0. 2) Russell coupled model: Ocean: Change of OCN MASS by OCN PHYS (10^-8 kg/s*m^2) = 0 Ocean: Change of OCN MASS by OCN DYNAM (10^-8 kg/s*m^2) = 0 Ocean: Sum of Changes of OCN MASS (10^-8 kg/s*m^2) = ( Open Ocean: [Precip - Evap] * OOfrac + Total Ocean: [Rvr Disch + Ice melt] * OCfrac)/ .000864 Land Water Budget ----------------- SUM OF CHANGES (10^-9 kg/m^2/s) [ LKICE MS + LAK MS + GRND WTR + LAND ICE ] * 0.0000864 = Land: [Precip-Evap] * GRfrac + Lakes: [Precip-Evap] * LKfrac + Land Ice: [Precip-Evap - Dwn Imp Wt Flx] * LIfrac - Oceans: [Rvr Disch] * OCfrac - Global: [Rvr Disch] Global river discharge takes into account the glacial calving flux - in a perfect world Land Ice: [Dwn Imp Wt Flx] * LIfrac would equal Global: [Rvr Disch]. Total Water Budget ------------------ Note if H2ObyCH4 is turned on, there is a small additional water source (H2O BY CH4(x1M)) but it is at least 3 orders of magnitude smaller than the next greatest term and so gets lost in the round off error. 1) Fixed SST models SUM OF CHANGES (10^-9 kg/m^2/s) [ ATM WAT *10 + LKICE MS + LAK MS + OICE MAS - OICE SLT/1000 + GRND WTR + LAND ICE ] * 0.0000864 = Global: [Rvr Disch] - Open Ocean: [Precip-Evap] * OOfrac - Oceans: [Dwn Imp Wt Flux + Rvr Disch + Ice Melt - Salt Melt/1000] * OCfrac - Land Ice: [Dwn Imp Mass] * LIfrac The implicit water flux term for the oceans compensates for the ice melt/formation flux that has nothing to do with the atmospheric cycle. The residual is the flux of snow into the ocean. 2) Qflux models SUM OF CHANGES (10^-9 kg/m^2/s) [ ATM WAT *10 + LKICE MS + LAK MS + OICE MAS - OICE SLT/1000 + GRND WTR + LAND ICE] * 0.0000864 = Global: [Rvr Disch] - Oceans: [Dwn Imp Wt Flx] * OCfrac - Land Ice: [Dwn Imp Mass] * LIfrac Conservation of Energy fluxes ----------------------------- 0 = Global: HEAT RUNOFF Note that the dynamics by itself does not guarantee that the energy lost from total potential energy is gained by the kinetic energy. There is a fix to put in this energy term (calculated a posteriori) at the end of DYNAM. Similarly, dissipation of KE is added in locally after surface friction, dry convection, atmopsheric turbulence and moist convection. There is similar coding in the FILTER, SDRAG and GWDRAG. If all of these energy changes are in place, then the total energy (KE+TPE+ENRG WAT) should be conserved. Conservation of Total Potential/Latent Energy in Atmosphere ----------------------------------------------------------- Atmosphere: Change of TPE by Dynamics (10^-2 W/m^2) / 100 + Atmosphere: Change of KE by Dynamics (10^-3 W/m^2) / 1000 = 0. Atmosphere: Change of TPE by Radiation (10^-2 W/m^2) / 100 = Global: [SW ABS BY ATMOS + NET LW AT P1 - NET LW AT Z0 + SW ABS BELOW P1 - SW ABS BELOW P0 + LW TO L1] = Global: [NET RAD AT P1 - NET RAD AT Z0 + LW TO L1] Atmosphere: Change of TPE by SURF+TURB (10^-2 W/m^2) / 100 = Global: - [SENSBL HEAT FLX + LW TO L1] Atmosphere: Change of TPE by CONDENSATN (10^-2 W/m^2) / 100 + Atmosphere: Change of ENRG WAT by CONDENSAT (10^-2 W/m^2) / 100 = Global: - [PRECIP HEAT FLX] Atmosphere: Change of TPE by KE DISSIP (10^-2 W/m^2) / 100 + Atmosphere: Change of KE by MOIST CONVEC (10^-3 W/m^2) / 1000 + Atmosphere: Change of KE by SURF +DC/TURB (10^-3 W/m^2) / 1000 = 0. Atmosphere: Sum changes of (TPE + KE + ENRG WAT) (10^-2 W/m^2) / 100 = Global: NET RAD AT P1 - NET HEAT AT Z0 Conservation of Energy in Ground -------------------------------- Ground: Change of GRND ENRG by EARTH (10^-3 W/m^2) = Ground: NET HT CNV GRND * GRfrac * 1000 Conservation of Energy in Lakes ------------------------------- Lakes: Change of LAK ENRG by RIVERS (10^-3 W/M^2) * 0.001 = Lakes: [Ht Rvr Disch] * LKfrac = - Oceans: [Ht Rvr Disch] * OCfrac + Global: [Ht Rvr Disch] (need global correction to account for net potential energy added - not used currently) Lakes: SUM Changes of LAK ENRG (10^8 W) * 0.01 / Area = Open Lake: [Net Heat at Z0] * LKOfrac + Lakes: [Ht Rvr Disch - Ht Runoff + Ht Ice Melt] * LKfrac Conservation of Potential Enthalpy by Liquid Ocean (coupled model) ------------------------------------------------------------------ Ocean: Change of OCN HEAT by OCN DYNAM = 0. Ocean: Change of OCN HEAT by Precipitation (10^-2 W/m^2) / 100 = Open Ocean: [Precip Heat Flx] * OOfrac Ocean: Change of OCN HEAT by SURF OCN FLX (10^-2 W/m^2) / 100 = Open Ocean: [Net Heat At Z0] * OOfrac + Ocean: [Ht Rvr Disch + Ht Ice Melt ] * OCfrac Conservation of Ocean/Lake Ice Energy ------------------------------------- Ocean Ice: Change of OICE ENRG by ADVEC (10^-3 W/m^2) = 0 In fixed SST models: Lake/Ocean Ice: SUM CHANGES OF ICE ENRG (10^-3 W/m^2) / 1000 = ( Ice covered: [Net Heat At Z0] * - total Oceans/Lakes: [Ht Ice Melt + Dwn Impl Ht Flx] * ) In coupled oceans: Lake/Ocean Ice: SUM CHANGES OF ICE ENRG (10^-3 W/m^2) / 1000 = ( Ice covered: [Net Heat At Z0] * - total Oceans/Lakes: [Ht Ice Melt] * ) As long as no ice crosses the equator, these conservation properties should also work for individual hemispheres. Total Energy Budget ------------------- 1) Fixed SST models SUM OF CHANGES (10-3 W/m^2) [ (TPE + ENRG WAT)*10 + KE + OICE ENR + LKICE EN + LAK ENRG + LNDI ENR ] /1000 = Global: [Net Rad at P0 - Dwn Imp Ht Flx] - Open Ocean: [Net Heat at Z0] * OOfrac - Oceans: [Ht Rvr Disch + Ht Ice Melt ] * OCfrac 2) Qflux models SUM OF CHANGES (10-3 W/m^2) [ (TPE + ENRG WAT)*10 + KE + OICE ENR + LKICE EN + LAK ENRG + LNDI ENR + OCN HEAT] /1000 = Global: [Net Rad at P0 - Dwn Imp Ht Flx]