BANE LAB RESEARCH
SABSOON, SABLAM and SEACOOS
(Harvey Seim, Cisco Werner, Brian Blanton and John Bane)
The South Atlantic Bight Synoptic Offshore Observational Network (SABSOON) was initiated in 1998 as a government/academia partnership to develop ocean observatory capabilities off the Georgia coast (Seim, 2000). The focus of the program was to instrument Navy-owned platforms with oceanographic and meteorological sensors to provide real-time information of the coastal ocean state. The program is entering its sixth year and continues to expand. A number of multi-year datasets now document shelf conditions throughout the year, and are revealing the nature of seasonal and interannual variability and a range of processes on the shelf including internal tides, benthic resuspension events and coherent offshore transport events.
The South Atlantic Bight Limited Area Modeling program was a NOPP-funded follow-on program to the initial SABSOON program that sought to develop a coastal ocean nowcast/forecast system that utilized the real-time SABSOON observations through data assimilation. It has significantly advanced our understanding of the tidal dynamics in the South Atlantic Bight and begun to clarify the importance (Blanton et al, 2003) and variability of density field on the shelf.
The SEACOOS program is an ONR-funded effort to plan and serve as a pilot regional coastal ocean observing system (Seim et al., 2003). It involves the simultaneous development of observing, modeling, data management and outreach/education activities in a coordinated fashion to enable a real-time information system for a significant portion of the US coastal ocean. The SABSOON and SABLAM programs were precursors to the SEACOOS regional activity and allowed the program to ramp up quickly. SEACOOS has a broader extent and includes new observing capabilities along the NC coastline (e.g., Stearns et al., 2004) as well as off the east and west coasts of Florida. Funding is provided by ONR and NASA; collaborators include Nelson, Jahnke, (SABSOON); and Lynch, McGuillicuddy and Welsh (SABLAM).
Observation and modeling of circulation, air-sea interaction and meteorological processes
Observational and modeling approaches have been used to study circulation, air-sea interaction and meteorological processes in shelf and slope regions along both coasts of the U.S. since the 1970s. These programs have used moored instrumentation, detailed ship surveys, rapid aircraft missions, and satellite data to obtain views of the time-varying, three-dimensional structure of the ocean and atmosphere. The development of techniques to provide synoptic looks at the environment has been emphasized. Another focus has been to obtain simultaneous observations of the ocean and atmosphere to aid in the study of how the systems interact. An example is the 3-D view of the coastal upwelling system off Oregon (Figure 3.33), which was obtained with one aircraft mission lasting < 8 hours. These results are from the NSF-funded CoOP study entitled COAST (Coastal Ocean Advances in Shelf Transport), which has more than a dozen co-principal investigators. Aircraft survey approaches yield reliable “snapshots” of the fluid environment. A series of such views can help visualize the system’s temporal evolution. Such surveys are particularly powerful when combined with slower but more detailed ship surveys, time series from moored instrumentation that give the temporal context of the aircraft measurements, and large-area views from satellites. Off the southeast U.S. coast, several flights were made during SABSOON (collaboration with H. Seim) to determine shelf and Gulf Stream thermal structure and variability, and to assess how their signatures are observed at fixed observatory sites.
Improvements in our understanding of the Oregon coastal upwelling system resulting from the combined use of these observational approaches include: (i) recognition of a stable internal boundary layer in the atmosphere immediately above the cool upwelled water that changes the wind stress pattern on the ocean, and thus the upwelling pattern, and (ii) the discovery of how intraseasonal oscillations in the jet stream over the NE Pacific cause wind fluctuations with periods around 20 days that set the dominant temporal scale in the coastal primary and secondary production fields.
Interactions between the ocean and the atmosphere during winter storms over U.S. east coast and Gulf Stream waters have been a topic of both observational and modeling efforts for the past several years. Collaborations with H. Xue, (Univ. Maine) have developed a hierarchy of models culminating in a three-dimensional, coupled atmosphere-ocean model of these processes. The results delineate the development of the atmospheric boundary layer and upper ocean during the passage of a winter cyclone. Of particular interest are: i) that the secondary circulations in the leading edge of the storm’s cold front are driven by ocean-to-atmosphere heat flux which in turn more strongly forces the ocean, and ii) that vertical circulation cells in the Gulf Stream are due to coupling between cooling, wind stress, and the larger-scale ocean current field.
Using the aircraft observing system, measurements of primary production and harmful algal concentrations have been made in coastal regions off North Carolina and Oregon. Repeated, detailed surveys off Oregon have shown how the water mass structure can be categorized into four types, based on its color and chlorophyll content. Working over North Carolina inshore and shelf waters, a new hyperspectral sensor that detects the UV band was flown to measure certain harmful algae. These efforts were funded by NASA-WFF and NSF, with ground-truth information collected by the NOAA Southeast Fisheries Center (Beaufort, NC).
Airborne Observing System for Shelf and Inshore Waters
(John Bane) (ONR, NOAA, NSF, NASA)
An instrumentation system has been developed to observe the oceanographic and meteorological processes in the coastal zone (Figure 3.34). The system is flown onboard a light, general aviation, twin-engine aircraft, and it provides measurements of atmospheric temperature, humidity, pressure and wind (onboard, in-situ sensors); sea surface temperature (remotely sensed), subsurface ocean temperature (deployed AXBTs), upper ocean color (remotely sensed) and upper ocean UV (remotely sensed). The system has been used in several projects during the past eleven years to study southerly surges in the summertime marine atmosphere off the US west coat, oceanic and atmospheric conditions off the southwestern US coast during the 1997-98 El Niño, Gulf Stream and continental shelf temperature structure and variability in the South Atlantic Bight, and wind-driven coastal upwelling off the northwestern US. It has also been used for instrumentation development in partnership with NASA Wallops, in a project that flew several missions over Pamlico Sound and the coastal waters out to the Gulf Stream off Cape Lookout. The new sensors are hyperspectral UV spectrometers that promise to give fast, remote sensing of harmful algal blooms in the coastal environment.
Figure 3.34. A schematic showing sensors used in the aircraft observing system developed by J. Bane for oceanic and atmospheric research. The Ocean Color Radiometer is a NASA-designed hyperspectral instrument that can determine several constituents in the surface waters below the aircraft. The inset shows the light, twin-engine aircraft used since 1994 in several research programs.
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