Marine Ecosystem Dynamics Modeling Laboratory

Mount Hope Bay Natural Laboratory (MHBNL)


The Mt. Hope Bay Natural Laboratory (MHBNL) developed through three major phases: 1) designing the framework, 2) developing a model system, and 3) conducting the field surveys to validate the model system.  Phase I covered the time period from July 2001 to June 2003, with a focus on a) assessing, assembling, and synthesizing historical field and modeling works accomplished in the Mt. Hope Bay region and b) designing the framework for formulating the laboratory. Phase 2 covered a time period from July 2003 to June 2004, with focus on a) the development of an integrated Mt. Hope Bay model system tool and b) the simulation of the realistic hydrodynamic field in the bay. Phase III started in July 2004 and continues to present, with a focus on the field measurement for the purpose of the model validation and assessment of the relative impact of natural (climate-warming) and anthropogenic (thermal plume) factors on  the bay environment.

The initial plan of MHBNL was to develop a model system by building a model system network with existing hydrographic models in this region. A careful assessment on existing models was made in phase I and process-oriented study showed that the hydrodynamic system in the Mt Hope Bay is controlled by strong tidal flushing through narrow straits linking to Narragansett Bay and Sakonnet River, multi-river discharges, cooling water outflow, and variable meteorological forcing. Due to the limitation in geometric fitting and horizontal resolution, none of existing models are capable to resolve the complex circulation system in the Mt. Hope Bay. Instead of the initial plan, we introduced an unstructured grid, finite-volume coastal ocean model (FVCOM) to the Mt. Hope Bay and used it as a framework to build a high resolution integrated atmospheric-ocean-ecosystem model system for this bay. This is the first inner bay model system that is capable of resolving irregular geometric structure and strongly tidal flushing and eddy shedding in Massachusetts and Rhode Island. Mass conservative unstructured grid finite-volume numerical technology used in this system leads this field of coastal and estuarine modeling and the accuracy and reality produced by this system make it capable to be used as a reliable environmental assessment and monitoring tool.

A model-validation field survey was carried by a multi-institutional cooperative effort of UMASSD and Woods Hole Oceanographic Institution (WHOI) in August 2005. This field work was led by Dr. Liuzhi Zhao with assistance from Drs. Changsheng Chen, Geoffrey Cowles and Don MacDonald (UMASSD) and Jim Churchill (WHOI). The measurement was focused on mapping the hot-water plume and locating tidal flushing-induced eddies. In the mapping survey, a high-resolution tow-yo CTD/ADCP measurement was made repeatedly in a tracking array covering an area from the exit of the hot-water discharge channel to the plume boundary in MHB. Two satellite-tracking surface drifters, operated by Jim Churchill at WHOI and Dr. Geoffrey Cowles at UMASSD, were released at the exit of the hot-water discharge during the cruise to mapping the recirculation cells due to the lateral shear instability of the jet current.  In the eddy survey, a CTD/ADCP measurement was made at pre-designed stations and repeatedly continuous tracks in an area where the eddy formed. Two satellite-tracking surface drifters were released in the NB/MHB channel during the flood tide to determine the current separation due to strong tidal flushing. A broad-scale coverage of MHB area made in the third survey provides an unique high resolution data for the model system validation.

The MHBNL is operated by a team effort of scientists at SMAST through collaboration with scientists at WHOI (for the field measurement). Brian Rothschild is Principal Investigator. The members of the model team include Dr. Changhsheng Chen (in charge of the modeling management). Dr. Liuzhi Zhao (Research Scientist in charge of the model development, numerical experiments and field measurement/data processing) and Dr. Geoffery Cowles (Research Scientist in charge of the code parallelization).


Posted on January 14, 2014