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[1] The biogeochemistry of continental shelf systems plays an important role in the global elemental cycling of nitrogen and carbon, but remains poorly quantified. We have developed a high-resolution physical-biological model for the U.S. east coast continental shelf and adjacent deep ocean that is nested within a basin-wide North Atlantic circulation model in order to estimate nitrogen fluxes in the shelf area of the Middle Atlantic Bight (MAB). Our biological model is a relatively simple representation of nitrogen cycling processes in the water column and organic matter remineralization at the water-sediment interface that explicitly accounts for sediment denitrification. Climatological and regionally integrated means of nitrate, ammonium, and surface chlorophyll are compared with its model equivalents and were found to agree within 1 standard deviation. We also present regional means of primary production and denitrification, and statistical measures of chlorophyll pattern variability. A nitrogen budget for the MAB shows that the sediment denitrification flux is quantitatively important in determining the availability of fixed nitrogen and shelf primary production (it was found to remove 90% of all the nitrogen entering the MAB). Extrapolation of nitrogen fluxes estimated for the MAB to the North Atlantic basin suggests that shelf denitrification removes 2.3 Â 10 12 mol N annually; this estimate exceeds estimates of N 2 fixation by up to an order of magnitude. Our results emphasize the importance of representing shelf processes in biogeochemical models.

A new four-dimensional ocean interpolation system based on locally weighted least squares fitting is presented. A loess filter is used to interpolate irregularly spaced data onto a uniform grid. This involves projecting the data onto quadratic functions of latitude and longitude while simultaneously fitting annual and semiannual harmonics by weighted least squares. The smoothness scale of the mapping method adapts to match the data density, thus producing gridded estimates with maximum resolution. The filter has a vertical dimension, such that the data on adjacent levels are included in the computation. This greatly reduces the effects of discontinuities in data distributions between adjacent levels, since the estimates at each level are no longer independent. The loess scheme has been further modified so that the weighting of data points is adjusted to allow for the influence of both bathymetry and land barriers. This allows the bathymetry to influence the mapped fields in a natural way, reduces leakage of structure between deep and shallow regions and produces far more realistic coastal gradients. The flexibility of the loess approach has allowed further adjustments to compensate for irregularities in spatial and temporal sampling. The mapping is shown to be statistically consistent with an objective measure of the a priori noise of the dataset. Departures of the mapped fields from independent surface temperature climatologies and mean vertical sections derived from withheld expendable bathythermograph (XBT) data are within error limits. The method is applied to the major seas around Australia, New Zealand, Papua New Guinea, and Indonesia (50ЊS-10ЊN, 100ЊE;-180Њ) to form a high-resolution seasonal climatology of temperature, salinity, oxygen, nitrate, phosphate, and silicate, referred to as the CSIRO (Commonwealth Scientific and Industrial Research Organisation) Atlas of Regional Seas (CARS). Stringent quality control procedures have been applied to a comprehensive dataset assembled from all known sources. The resulting maps successfully resolve both the large-scale structure and narrow coastal features and illustrate how the bathymetry influences the property distributions.

B y E r i c P. c h a s s i g N E t, h a r l E y E . h u r l B u r t, E . J o s E P h M E t z g E r , o l E M a r t i N s M E d s ta d , J a M E s a . c u M M i N g s ,g E o r g E r . h a l l i w E l l , r a i N E r B l E c k , r E M y B a r a i l l E , The partnership represents a broad spectrum of the oceanographic community, bringing together academia, federal agencies, and industry/commercial entities, and spanning modeling, data assimilation, data management and serving, observational capabilities, and application of HYCOM prediction system outputs. In addition to providing real-time, eddy-resolving global-and basin-scale ocean prediction systems for the US Navy and NOAA, this project also offered an outstanding opportunity for NOAA-Navy collaboration and cooperation, ranging from research to the operational level. This paper provides an overview of the global HYCOM ocean prediction system and highlights some of its achievements. An important outcome of this effort is the capability of the global system to provide boundary conditions to even higherresolution regional and coastal models.Oceanography Vol. In addition to operational eddyresolving global-and basin-scale ocean prediction systems for the US Navy and NOAA, respectively, this project offered an outstanding opportunity for NOAA-Navy collaboration and cooperation ranging from research to the operational level.

[1] The contribution of coastal oceans to the global air-sea CO 2 flux is poorly quantified due to insufficient availability of observations and inherent variability of physical, biological and chemical processes. We present simulated air-sea CO 2 fluxes from a high-resolution biogeochemical model for the North American east coast continental shelves, a region characterized by significant sediment denitrification. Decreased availability of fixed nitrogen due to denitrification reduces primary production and incorporation of inorganic carbon into organic matter, which leads to an increase in seawater pCO 2 , but also increases alkalinity, which leads to an opposing decrease in seawater pCO 2 . Comparison of simulations with different numerical treatments of denitrification and alkalinity allow us to separate and quantify the contributions of sediment denitrification to air-sea CO 2 flux. The effective alkalinity flux resulting from denitrification is large compared to estimates of anthropogenically driven coastal acidification.