Fully-Coupled and Forced Ocean Sea-Ice Simulations Towards CESM2 (since mini-breck) Defining the Ocean Component of CESM2

Transcription

1 Fully-Coupled and Forced Ocean Sea-Ice Simulations Towards CESM2 (since mini-breck) Defining the Ocean Component of CESM2

2 OMWG PLAN FOR DEFINING THE CESM2 OCEAN COMPONENT Timeline 01 March April 2016: Finish individual evaluation of all developments; 29 April 2016: Combine promising developments together and start performing G- and B-compset simulations and re-tune, if needed; 03 June 2016: Finalize all simulations and assessments of model simulations; June 2016: Discuss what should be included in the CESM2 ocean component at the OMWG meeting at Breckenridge; 29 June 2016: Define the CESM2 ocean component for consideration of the CESM SSC.

3 OMWG PLAN FOR DEFINING THE CESM2 OCEAN COMPONENT 01 March 2016 New features 0. Community ocean Vertical Mixing (CVMix) framework, a. Langmuir mixing parameterization & WaveWatch III, b. Enhanced mesoscale eddy diffusivities at depth, c. Specification of mesoscale eddy diffusivities via steering level approach, d. Anisotropic mesoscale eddy diffusivities, e. Tidal mixing parameterizations, f. Estuary parameterization, g. Robert Asselin time filter (sub-daily coupling, e.g., every 2 hours). a. Salinity-dependent freezing point temperature (also in CICE5), b. Prognostic chlorophyll, c. Near-Inertial wave parameterization.

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5 Community ocean Vertical Mixing (CVMix) Framework Levy, Danabasoglu, & Large (NCAR); Griffies, Adcroft, & Hallberg (GFDL); Ringler & Jacobsen (LANL) CVMix is a software package that aims to provide transparent, robust, flexible, well-documented, and shared Fortran source codes for use in parameterizing vertical mixing processes in ocean models. CVMix modules are used in POP2, MPAS-O, and MOM6. In POP2, K-Profile Parameterization (KPP) is enabled via CVMix.

6 Langmuir Mixing (LM) Parameterization & WaveWatch III Li, Webb, & Fox-Kemper Brown University Craig, Danabasoglu, Large, & Vertenstein NCAR Enhanced mixing within the oceanic boundary layer through Langmuir turbulence Some restrictions

7 Annual-Mean Mixed Layer Depth Winter-Mean #36 - OBS m LM/WW3 - #36 Density change of kg m -3

8 Meridional Overturning Circulation Temperature at 50-m Depth LM LM - #36

9 Enhanced Mesoscale Eddy Diffusivities at Depth Improvements in Ocean Physics Parameterizations Reduce Denitrification, Improving the Global Ocean Nitrogen Balance #36 MP.3

10 Sub-Daily Coupling of Ocean (Every Two Hours) Mixed-Layer Depth (EXP - #36) Meridional Overturning Circulation m Current experiments w/ Leap-frog & time averaging RF is running w/ almost correct tracer budgets EXP - #36

11 Salinity Dependent Freezing Point Temperature (also in CICE5) T f = -1.8 o C T f = S / ( *S) where S in psu

12 Salinity Dependent Freezing Point Temperature (also in CICE5) T f = -1.8 o C T f = S / ( *S) where S in psu EXP #36 Meridional Overturning Circulation EXP EXP - #36

13 Prognostic Chlorophyll Better physics Expected to capture feedbacks in a changing climate (e.g., melting sea-ice)

14 Specification of Mesoscale Eddy Diffusivities via Steering Level (SL) Approach Ferrari & Nikurashin (2010, JPO) Bates, Tulloch, Marshall, & Ferrari (2014, JPO) Steering levels: Surfaces / regions at which the propagation speed of mesoscale eddies approach that of the mean flow; Maximum mixing occurs at the steering levels; Mixing is strongly suppressed away from the steering levels, e.g., in strong flows where the mean flow and propagation speed of eddies differ significantly; When the eddies propagate at a speed different from the mean flow, some of the tracer can be advected by the mean flow out of the eddy before it is fully mixed, i.e., there is not enough time for mixing and it is suppressed; In contrast, when the eddies move with the flow, mixing can be more effective, i.e., no suppression of mixing.

15 Global Zonal-Mean Diffusivity Distributions Global Zonal Average m 2 s -1

16 Anisotropic Mesoscale Eddy Diffusivities SST (AGM - #36) Mixed-Layer Depth (AGM - #36) m

17 Anisotropic Mesoscale Eddy Diffusivities Meridional Overturning Circulation #36 AGM

18 New Tidal Mixing Parameterizations / Approaches Implemented in POP2 New dissipation energy flux fields from the barotropic tides from Egbert & Ray (2003; EG03) and Green & Nycander (2013; GN13) current default is based on Jayne & St. Laurent (2001; JS01), Effects of subgrid-scale bathymetry in the energy flux field, following Schmittner & Egbert (2014; SE14), Separation of semi-diurnal and diurnal tides with different local dissipation efficiency, following SE14, Algebraic decay of dissipation energy, following Polzin (2009) à la Melet et al. (2013), Incorporation of the 18.6-year Lunar Nodal Cycle (LNC)

19 Updated from Whalen et al. (2012)

20 LNC and Kuril Strait

21 Merged Parameterization Simulation (MP.3) Atmosphere and Land from #36 Sea-ice from #36 + T f (S) Ocean Model: 0. Community ocean Vertical Mixing (CVMix) framework, a. Langmuir mixing parameterization & WaveWatch III, b. Enhanced mesoscale eddy diffusivities at depth, c. Specification of mesoscale eddy diffusivities via steering level approach, d. Anisotropic mesoscale eddy diffusivities, e. Tidal mixing parameterizations, f. Estuary parameterization, g. Robert Asselin time filter (sub-daily coupling, e.g., every 2 hours). a. Salinity-dependent freezing point temperature (also in CICE5), b. Prognostic chlorophyll, c. Near-Inertial wave parameterization.

22 Keith Lindsay

23 Time-Mean Boundary Layer Depth #79 MP.3 #79 - #36 MP.3 - #36

24 SST Differences from Observations LE #36 MP.3 #79

25 Sea Surface Salinity Differences from Observations LE #36 MP.3 #79

26 Global (top) and Atlantic (bottom) Meridional Overturning Circulations (Sv) LE #36 MP.3 #79

27 Ocean Model Features for CESM2 0. Community ocean Vertical Mixing (CVMix) framework, a. Langmuir mixing parameterization & WaveWatch III, b. Enhanced mesoscale eddy diffusivities at depth, c. Specification of mesoscale eddy diffusivities via steering level approach, d. Anisotropic mesoscale eddy diffusivities, e. Tidal mixing parameterizations, f. Estuary parameterization, g. Robert Asselin time filter (sub-daily coupling, e.g., every 2 hours). a. Salinity-dependent freezing point temperature (also in CICE5), b. Prognostic chlorophyll, c. Near-Inertial wave parameterization.

28 Near-Inertial Wave (NIW) Parameterization Jochum et al. (2013) Meridional Overturning Circulation Temperature at 50-m Depth NI W NIW - CONT

29 Estuary Parameterization Q out > Q R S out > 0 See Poster OMWG-8

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31 Equatorial Pacific Currents at 205 o E MP.3 #79

32 Mixed Layer Depth Annual-Mean Winter-Mean CONTROL - OBS SL - CONTROL m

33 CONTROL Meridional Overturning Circulation (Sv) SL Atlantic Northward Heat Transport SL CONTROL