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For 11 days in January 2002, the Conrad Blucher Institute for Surveying and Science, Texas A&M University-Corpus Christi, in collaboration with the College of Marine Science, University of South Florida, deployed a pair of 25-MHz CODAR Ocean Systems HF-radars on the West Florida Shelf over an array of six acoustic Doppler current profilers. The radar footprint had a maximum range of 60 km offshore, and it included mooring locations between the 10 m to 30 m isobaths. We examine, using a variety of metrics, the correlation between the surface currents measured remotely by the HF-radar and the subsurface currents measured by the ADCPs, which were either bottom- or surface buoy-mounted. Qualitative comparisons are generally good for this inner-shelf environment where the wind-driven current magnitudes were less than about 40 cm/s. The scalar regression analysis shows correlation coefficients (R) of 0.8 to 0.9 for the alongshelf components but 0.6 or less for the cross-shelf components. Complex vector correlation produces correlation values of 0.76 to 0.90 and a consistently clockwise veering from the radar-measured currents to the ADCP-measured ones ranging from 1.3 to 5.2 . The alongshelf surface currents measured by the radar are about 30% larger than those of the ADCPs measured 2 to 3 m below the surface according to standard deviations and linear regression slopes.

[1] Atmosphere model-derived flux fields are used to force coastal ocean models. Coarse resolution and incomplete boundary layer dynamics limit the accuracy of these forcing fields and hence the performance of the ocean models. We address this limitation for the west Florida shelf using optimal interpolation to blend winds measured in situ with winds produced by model analyses. By improving the coastal wind field we improve the fidelity between currents modeled and currents observed. Comparisons between momentum analyses performed independently from the model and the data demonstrate the fidelity to be of a correct dynamical basis. We conclude that the primary limitation to coastal ocean model performance lies with the boundary conditions.

[1] Clouds are problematic in using Advanced Very High Resolution Radiometer (AVHRR) imagery for describing sea surface temperature (SST). The Tropical Rainfall Measuring Mission Microwave Imager (TMI) observes SST through clouds, providing daily, 1/4° maps under all weather conditions excepting rain. A TMI limitation, however, is coarse resolution. Optimal interpolation (OI) is used to generate a cloud-free, 5-km, daily SST analysis for the West Florida Shelf (WFS) by merging the high-resolution (cloud-covered) AVHRR with the coarse-resolution (cloud-free) TMI SST products. Comparisons with in-situ data show good agreements. Given large spatial gradients by coastal ocean processes, this regional analysis has advantage over the global, weekly, 1° Reynolds SST. A 5-year (1998–2002) OI SST analysis is diagnosed using Empirical Orthogonal Functions. The first two modes represent annual cycles, one by surface heat flux and another by shelf circulation dynamics.

[1] We have combined a circulation model with one of colored dissolved organic matter (CDOM) photolysis to describe the fate of terrestrial CDOM on the West Florida shelf (WFS). Our results for summer 1998 suggest that a near shore plume of CDOM became entrained in a coastal jet extending south from the Suwannee River (Big Bend) region of the WFS towards the Florida Keys—a feature also evident in satellite ocean color imagery. The coupled models suggest that photochemical losses of CDOM were significant, but provided only a minimal nitrogen source for phytoplankton growth on the WFS.

[1] Material property distributions on continental shelves result from the mixing and modifications of estuarine and deep-ocean source waters. How this occurs depends on the momentum and buoyancy that are input either locally on the shelf or from the deep-ocean at the shelf break. We address this question of local versus deep-ocean forcing for the West Florida Shelf (WFS) using in situ data and a numerical circulation model. The spring and summer seasons of 1998 and 1999 show distinctively different water properties on the shelf and at the shelf break. We account for these differences by a combination of local forcing, independent of the adjacent Gulf of Mexico Loop Current, and interactions of the Loop Current with the shelf. The primary role of the deep ocean is to set the height of material isopleths along the shelf slope. Whether or not these material isopleths broach the shelf break is then a consequence of local, shelf-wide wind and buoyancy forcing. The subsequent along- and across-shelf distributions are accomplished through a combination of local and deep-ocean effects, with the bottom Ekman layer being the major conduit for the across-shelf transport of ecologically important materials.

[1] Previous hypotheses had suggested that upwelled intrusions of nutrient-rich Gulf of Mexico slope water onto the West Florida Shelf (WFS) led to formation of red tides of Karenia brevis. However, coupled biophysical models of (1) wind- and buoyancy-driven circulation, (2) three phytoplankton groups (diatoms, K. brevis, and microflagellates), (3) these slope water supplies of nitrate and silicate, and (4) selective grazing stress by copepods and protozoans found that diatoms won in one 1998 case of no light limitation by colored dissolved organic matter (CDOM). The diatoms lost to K. brevis during another CDOM case of the models. In the real world, field data confirmed that diatoms were indeed the dominant phytoplankton after massive upwelling in 1998, when only a small red tide of K. brevis was observed. Over a 7-month period of the CDOM-free scenario the simulated total primary production of the phytoplankton community was ∼1.8 g C m−2 d−1 along the 40-m isobath of the northern WFS, with the largest accumulation of biomass on the Florida Middle Ground (FMG). Despite such photosynthesis, these models of the WFS yielded a net source of CO2 to the atmosphere during spring and summer and suggested a small sink in the fall. With diatom losses of 90% of their daily carbon fixation to herbivores the simulation supported earlier impressions of a short, diatom-based food web on the FMG, where organic carbon content of the surficial sediments is tenfold those of the surrounding seabeds. Farther south, the simulated near-bottom pools of ammonium were highest in summer, when silicon regeneration was minimal, leading to temporary Si limitation of the diatoms. Termination of these upwelled pulses of production by diatoms and nonsiliceous microflagellates mainly resulted from nitrate exhaustion in the model, however, mimicking most del15PON observations in the field. Yet, the CDOM-free case of the models failed to replicate the observed small red tide in December 1998, tagged with the del15N signature of nitrogen fixation. A large red tide of K. brevis did form in the CDOM-rich case, when estuarine supplies of CDOM favored the growth of the shade-adapted, ungrazed dinoflagellates. The usual formation of large harmful algal blooms of >1 ug chl L−1 (105 cells L−1) in the southern part of the WFS, between Tampa Bay and Charlotte Harbor, must instead depend upon local aeolian and estuarine supplies of nutrients and CDOM sun screen, not those from the shelf break. In the absence of slope water supplies, local upwelling instead focuses nitrate-poor innocula of co-occurring K. brevis and nitrogen fixers at coastal fronts for both aggregation and transfer of nutrients between these phytoplankton groups.

Mid-latitude continental shelves undergo a spring transition as the net surface heat flux changes from cooling to warming. Using in-situ data and a numerical circulation model we investigate the circulation and temperature budget on the West Florida Continental Shelf (WFS) for the spring transition of 1999. The model is a regional adaptation of the primitive equation, Princeton Ocean Model forced by NCEP re-analysis wind and heat flux fields and by river inflows. Based on agreements between the modeled and observed fields we use the model to draw inferences on how the surface momentum and heat fluxes affect the seasonal and synoptic scale variability, We account for a strong southeastward current at mid-shelf by the baroclinic response to combined wind and buoyancy forcing, and we show how this local forcing leads to annually occurring cold and low salinity tongues. Through term-by-term analyses of the temperature budget we describe the WFS temperature evolution in spring. Heat flux largely controls the seasonal transition, whereas ocean circulation largely controls the synoptic scale variability. Rivers contribute to the local hydrography and are important ecologically. Along with upwelling, river inflows facilitate frontal aggregation of nutrients and the spring formation of a high concentration chlorophyll plume near the shelf break (the so-called 'Green River'), coinciding with the cold, low salinity tongues. These features originate by local, shelf-wide forcing; the Loop Current is not an essential ingredient for spring transition of 1999.

Ocean gliders are a powerful platform for collecting large-scale data on the distribution of sound-producing animals while also collecting environmental data that may influence their distribution. Since 2009, we have performed extensive mapping on the West Florida Shelf with ocean gliders equipped with passive acoustic recorders. These missions have revealed the distribution of red grouper as well as identified several unknown sounds likely produced by fishes. In March 2014, we ran a mission along the shelf edge from Cape Canaveral, FL to North Carolina to map fish sound production. The Gulf Stream and its strong currents necessitated a team effort with ocean modeling to guide the glider successfully to two marine protected areas. This mission also revealed large distributions of unknown sounds, especially on the shallower portions of the shelf. Gliders provide valuable spatial coverage, but because they are moving and most fish have strong diurnal sound production patterns, data analysis on presence and absence must be made carefully. In many of these cases, it is best to use a combination of platforms, including fixed recorders and ocean profilers to measure temporal patterns of sound production.

The main objective is to use the HYbrid Coordinate Ocean Model (HYCOM) with data assimilation in an eddy-resolving, fully global ocean prediction system with transition to the Naval Oceanographic Office (NAVOCEANO) at .08 deg equatorial (~7 km mid-latitude) resolution in 2007 and .04 deg resolution by 2011. The model will include shallow water to a minimum depth of 5 m and provide boundary conditions to finer resolution coastal and regional models that may use HYCOM or a different model. In addition, HYCOM will be coupled to atmospheric, ice and bio-chemical models, with transition to the Fleet Numerical Meteorology and Oceanography Center (FNMOC) for the coupled ocean-atmosphere prediction. Basin-scale configurations will also form the backbone of the NOAA/NCEP/MMAB Ocean Forecast System. All the systems will be transitioned with assimilation of sea surface height (SSH) from satellite altimeters, sea surface temperature (SST) and temperature (T)/salinity (S) profiles, including profiles from ARGO floats. In addition, 30-day forecasts are planned once a week. The global system will include two-way coupling to an ice model and a version with two-way coupling to an atmospheric model for transition to FNMOC. The project will ensure that an accurate and generalized ocean model nesting capability is in place to support regional and littoral applications when global HYCOM becomes operational. This will include the capability to provide boundary conditions to nested models with fixed depth z-level coordinates, terrain following coordinates, generalized coordinates (HYCOM), and unstructured grids. To facilitate this goal, HYCOM will be developed into a full-featured coastal ocean model in collaboration with a partnering project. The project will participate in the multinational Global Ocean Data Assimilation Experiment (GODAE) and international GODAE-related ocean prediction system intercomparison projects.