Coupling ROMS and CSIM in the Okhotsk Sea

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Coupling ROMS and CSIM in the Okhotsk Sea

• Rebecca Zanzig
• University of Washington
• November 7, 2006

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Outline

• Motivation
• ROMS Configuration
• CSIM Model Specifications
• Coupling Between Models
• Heat and Freshwater Fluxes
• Surface stresses
• Preliminary Results
• Future Work

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Motivation

• To couple a terrain-following regional ocean
  model (ROMS) with a state-of-the-art ice model
  (CSIM).
• Apply this new model configuration to the Sea of
  Okhotsk, which is the formation region for North
  Pacific Intermediate Water.
• Investigate the deep water formation in the
  region and the impact of sea ice on it.
• Investigate the impact of tides on sea ice.

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Grid Setup

• Resolution
• 43-63 N, 135-165 E
• 16-23 km resolution
• 20 vertical levels
• ETOPO5 Bathymetry
• 3000 meter maximum depth
• East, South and West open boundaries

Open boundary forcing thanks to the North
Pacific model by Al Hermann and Liz Dobbins at
PMEL
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CPP Options

• LMD interior mixing
• KPP surface and bottom boundary layer mixing
• Splines
• Third-order upstream bias horizontal advection of
  tracers
• Surface salinity flux correction
• Open Boundaries (East, South and West)
• Chapman free-surface condition
• Flather 2D-momentum condition
• Radiation condition for 3D-momentum and tracers

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Forcing Data

• Coordinated Ocean-ice Reference Experiments
  (CORE) dataset
• 6 hourly
• Winds
• Relative Humidity
• Sea level pressure
• Sea level air temperature
• Daily
• Incoming shortwave radiation
• Incoming longwave radiation
• Monthly
• Precipitation (Rain and Snow)
• World Ocean Atlas

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Community Climate System Sea Ice Model (CSIM)

• Dynamic and Thermodynamic ice model
• Elastic- Viscous- Plastic Dynamics
• Supports Multiple ice types
• Used in CCSM- global climate model
• Modified to run in regional applications
• Capable of computing fluxes over both ice and the
  open ocean

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ROMS CSIM Coupling
ROMS
CSIM
Freshwater Fluxes
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Downward Flux Incoming (1 aice)
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TerrainFollowing Issues Frzmlt
level at_hmin at_hmax 20 0.000
0.000 19 -0.500 -2.855
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TerrainFollowing Issues Frzmlt
Temp lt -1.8 ºC
Temp gt -1.8 ºC
Temp gt -1.8 ºC
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TerrainFollowing Issues Frzmlt
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Results SST Surface Currents
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Results - Ice Thickness
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Results - Percent Ice Coverage
3 year mean
30 year mean
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Scherbina et al (2004)

• Data along northwestern shelf from 2 bottom
  moorings and a hydrographic survey in September
  1999
• Factors thought to be important to dense water
  formation
• Location of the tidal mixing front
• Baroclinic instability could stop dense water
  formation

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Bottom Temperature
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Density Section
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Temperature Section
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Future Work

• Add tides to the simulation
• Refine resolution
• Interannual variability (not just climatological
  forcing)
• Examine ventilation and deep water formation
• Include the Amur River in simulation

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