Research Modeling

Modeling efforts have focused on developing the Regional Ocean Modeling System (ROMS) for the northeastern Gulf of Mexico and conducting a modeling study on the impacts of the Apalachicola River on the marine ecosystems of the region. The ROMS physical ocean model will become the backbone for a multidisciplinary coupled physical - biogeochemical - atmospheric modeling system with real-time capability. The purpose of the modeling system is to support and utilize NGI observational efforts in the region, and to provide a tool for integrated multidisciplinary research efforts for the local marine system. The modeling system will also serve as a laboratory for air-sea interaction studies, data assimilation studies, and algorithm development.

Accomplishments for the project are:

  1. ROMS has been ported to COAPS and FSU supercomputing facilities and configured for a realistic 30-arcsec (approximately 900 m) resolution northeastern Gulf of Mexico domain (Fig. 4) with representation of major estuaries and fifteen river sources.
  2. The model topography and coastline geometry has been carefully hand-edited to provide for representation of major estuaries and fifteen river sources have been implemented.
  3. Scripting tools have been developed to acquire and process real-time atmospheric model data for the ocean simulation.
  4. Data processing tools have been developed for automation of river gauge raw data acquisition, quality control, and detiding for use as real-time forcing for the ocean model.
  5. Forced simulations have been run to investigate appropriate model numerical options and methods for coupling to the larger scale HYCOM model.
  6. The northeastern Gulf of Mexico ROMS simulation has been nested within a 1/25° HYCOM southeastern United States ocean model to provide for real-time boundary conditions.
  7. The Advanced Research WRF (ARW) atmospheric modeling system has been configured for the BBR using a nesting approach and is being used to investigate land-sea breeze circulation and cold air outbreaks over the region.
  8. A journal paper has been submitted showing mechanisms for connecting variability in terrestrial precipitation and flow in the Apalachicola River with physical and biological variability offshore over the northern West Florida Shelf using numerical model simulations and observational data analysis (Morey et al., 2007).

As a first interdisciplinary modeling and data analysis project, Morey et al. (2008) demonstrated linkage between interannual variability of precipitation over the Apalachicola River watershed and offshore marine bio-optical properties. This work concluded that during winter and spring months when interannual precipitation variability is greatest, intermittent bursts of upwelling-favorable winds associated with cold frontal passages transport low salinity - high nutrient water from the Apalachicola River plume offshore in jet-like features. Thus variability in the water properties within the plume induced by varying river discharge becomes connected to the offshore region, over known spawning areas for regionally important finfish. This project is a first step in better understanding the connections between the physics and biology of the region, as well as terrestrial and coastal properties with offshore fisheries habitats.

Cold frontal passages occurring during cold air outbreaks (CAOs) have been shown in our modeling efforts to influence the movement ofhigh nutrient water further offshore, as well as increasing mixing and upwelling along the coast. An analysis of roughly 30 years of NCEP North AmericanReanalysis model results have shown that in addition to this effect, over 60% of the heat loss during the winter and early spring occurs during these events. There is strong interannual variability in the number of these events, but much less variability in the amount of total cooling that they generate. The reasons for this are unknown. We have also determined that there is a substantial difference in wind speeds and cooling between the western and eastern parts of the basin, for reasons that are still unknown. Given the importance of these events in maintaining the physical and ecological structure of the coastal waters, we will continue to evaluate the air-sea coupling of these events using our higher-resolution model. We will evaluate the model's response with respect to changes in the ocean and atmospheric boundary layers during these events by comparisons with available buoy data and the invaluable fluxes from the instrumented towers. We will then investigate whether these east/west and interannual differences are due to larger-scale climate patterns or air-sea coupling, perhaps through variability in the location/strength of the Loop Current.