ROMS in Alaska Waters
Kate Hedstrom, ARSC/UAF
Enrique Curchitser, IMCS/Rutgers
August, 2007
• GLOBEC and related modeling
– NEP runs so far
– Forcing
– Plans
– Tides
• CCSM connection
– CORE forcing, POP global ocean for
– Coupling underway at NCAR
The Model
• ROMS ocean
– Coupled ecosystem models
– Now with an adjoint and tangent linear for
data assimilation
• Ice model from Paul Budgell
– EVP dynamics (Arakawa C grid)
– Mellor-Kantha thermodynamics
– Oceanic molecular sublayer under the ice
for improved behavior
NEP Implementation
• 10 km average horizontal resolution
• Run1:
30 vertical layers
IC’s and BC’s from NPac
Daily fluxes from NCEP hindcast (modified)
1996-2002, 1960-1970
• Run2:
– 42 vertical layers
– Six-hourly fluxes from Common Ocean-ice Reference
Experiments (CORE) reanalysis
– IC’s and BC’s from CCSM (POP) forced by CORE
– 1958-2004
Evaluation of Latest
• We are much happier with the heat
fluxes from CORE
• Ice area seems quite realistic
• Still could do better:
– Not enough fresh water input at the coast
– Stratification in general isn’t quite right, will
perhaps be improved by tidal mixing
– We want a shallower minimum depth
• We also need to add an ecosystem
model for GLOBEC, plus need to test
the new NEMURO implementation
Ice Area and Volume
Zoom In
Tides in the Bering Sea
• We have an effort underway to
evaluate the tides in the model
with Zigmunt Kowalik and Seth
• We started with the 4 km Bering
Sea domain in 2-d with four tidal
• We are ultimately interested in
the complex 3-d structure
CCSM Coupling
• Thanks to the CORE group’s products,
we no longer need to run the large NPAC
domain (proof of one-way coupling)
• The CCSM model does fine for its
resolution, but fails in regions needing
more resolution (coastal upwelling)
• The idea is to couple ROMS to CCSM,
where ROMS is part of a “composite
ocean” providing a better sea surface
temperature to the atmosphere
CCSM Strategy
• The coupling interval is one day, with
the atmosphere running ahead
• The composite ocean will receive
hourly winds, etc. and interpolate to
ROMS grid(s)
• POP runs for that day, sends “curtains”
out for ROMS nests
• ROMS runs for that day
• Composite ocean merges SST from POP
and ROMS for CAM
• We are excited about this opportunity
to work with the CCSM group
• A similar effort is underway to add
WRF as a regional atmospheric model
• One of the people we’ve been
working with is on the ESMF team at
NCAR and wants to make a
standalone ESMF-ready version of

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