HR: 14:00h
AN: OS52G-01 INVITED     [PDF]
TI: Modeling the Summertime Heat Budget of Southeast New England Shelf Waters
AU: * Wilkin, J
EM: jwilkin@rutgers.edu
AF: John Wilkin, IMCS Rutgers University 71 Dudley Road, New Brunswick, NJ 08901 United States
AU: Lanerolle, L
EM: lanerolle@marine.rutgers.edu
AF: John Wilkin, IMCS Rutgers University 71 Dudley Road, New Brunswick, NJ 08901 United States
AB: The Regional Ocean Modeling System (ROMS) has been configured for the southeast New England shelf encompassing the Coupled Boundary Layers and Air-Sea Transfer study area. CBLAST observations of air-sea fluxes and ocean vertical mixing, velocity, and stratification are well suited to evaluating components of a coupled ocean-atmosphere modeling system. The model configuration was designed to capture the essential features of the heat budget on diurnal to weekly time scales, and space scales of a few kilometers. The model has 1 km grid spacing, accurate bathymetry, and inflow/outflow open boundaries incorporating tides and a bi-monthly climatology of circulation. Air-sea fluxes are computed using bulk formulae applied to the model temperature and marine boundary layer conditions from a high-resolution atmospheric forecast. One objective of the modeling study is to quantify the role of lateral transport and coastal mesoscale heterogeneity in the depth-integrated heat budget, thereby identifying an important unobserved term in analyses of the observational data. Summer 2002 simulations show the influences of winds and tides compete; wind-driven eastward circulation opposes a mean current that branches from tidal rectified anti-cyclonic flow encircling the Nantucket Shoals. On the flank of the shoals, tides mix the water column maintaining perpetually cold surface temperatures. Mean air-sea flux is greatest east of Nantucket Sound in the region of cool SST, and is balanced by horizontal divergence. During July, heat storage is largest south of the Islands where surface heating is still warming the water, whereas shallower waters have reached summer equilibrium. In the environs of the Martha's Vineyard Coastal Observatory, half the air-sea flux goes to warming the water column while half is removed by horizontal divergence. In the model, tidal eddies exiting Nantucket Sound pass through the MVCO region, producing an eddy heat divergence. Further south of the Vineyard, there is an approximate 1-D vertical heat balance. A second objective is evaluation of the suite of vertical turbulence parameterizations implemented in ROMS: the k-profile parameterization, Mellor-Yamada, and multiple options within the Generic Length Scale scheme. Temperature and velocity profiles from moorings throughout the region are available to validate the sensitivity of the modeled stratification and circulation to turbulence closure. The model ran operationally for the 2003 observing period using hourly 3-km resolution atmospheric forcing from the multiple-nested US Navy COAMPS forecast system. Initial analysis shows significant differences in predicted stratification and air-sea heat flux for different closure options. Future analysis will compare parameterized and observed vertical mixing processes.
UR: http://marine.rutgers.edu/~wilkin/wip/cblast/cblast2003.htm
DE: 4255 Numerical modeling
DE: 4504 Air/sea interactions (0312)
DE: 4568 Turbulence, diffusion, and mixing processes
SC: Ocean Sciences [OS]
MN: 2004 Ocean Sciences Meeting