roms in alaska waters kate hedstrom, arsc/uaf enrique curchitser, imcs/rutgers august, 2007
TRANSCRIPT
ROMS in Alaska Waters
Kate Hedstrom, ARSC/UAFEnrique Curchitser, IMCS/Rutgers
August, 2007
Overview
• GLOBEC and related modeling– NEP runs so far– Forcing– Plans– Tides
• CCSM connection– CORE forcing, POP global ocean for
boundaries– 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 Simulation
• 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 Danielson
• We started with the 4 km Bering Sea domain in 2-d with four tidal constituents
• 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
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
Conclusions
• 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 ROMS