Research Topics

Research in my group focuses on boundary, coastal, and equatorial current systems. We primarily use autonomous underwater gliders (http://gliders.whoi.edu) to collect long-duration, high-resolution observations that are then analyzed to understand upper ocean dynamics in these regions. We work in a variety of temperate and tropical locations around the world.

Gulf Stream

The Gulf Stream is the mid-latitude western boundary current of the North Atlantic and plays a key role in the Earth’s climate system as it transports heat from the tropics to mid-latitudes. Despite its proximity to the US East Coast, the Gulf Stream has been chronically under sampled. We are using Spray gliders to collect high-resolution transects across the Gulf Stream as it flows along the US East Coast between Florida and New England, filling a critical gap in long-duration, subsurface observations of this important current. This work has been funded by NSF, ONR, NOAA, Eastman Chemical, and WHOI. For more on our Gulf Stream work, please go here.

Cape Hatteras (PEACH)

Offshore of Cape Hatteras, NC, coastal waters from the Middle Atlantic Bight and South Atlantic Bight converge in close proximity to the Gulf Stream as it separates from the continental margin. The NSF-funded ‘Processes driving Exchange At Cape Hatteras (PEACH)’ program aims to understand the dynamics controlling exchange between the continental shelf and deep ocean in this highly variable area. Observations from a variety of observation platforms, including gliders operators by our group, are being combined with numerical models to understand the drivers of exchange. Information on the entire PEACH program is available here. Details of our work in support of PEACH are here.

Equatorial Indian Ocean (NASCar and MISO-BOB)

Circulation in the equatorial and tropical Indian ocean is strongly influenced by the Asian monsoon, which has large-scale winds switching directions twice per year. As part of two ONR-funded DRIs, ‘Northern Arabian Sea Circulation–autonomous research (NASCar)’ and ‘Oceanic Control of Monsoon Intra-seasonal Oscillations in the Tropical Indian Ocean and the Bay of Bengal (MISO-BOB)’, we are conducting glider surveys in the western equatorial Indian Ocean and the Bay of Bengal. For more information on our Indian Ocean work, please go here.

Middle Atlantic Bight (TEMPESTS and Pioneer)

The continental shelf circulation over the Middle Atlantic Bight is strongly influenced¬†by both offshore forcing (e.g., Gulf Stream rings) and passing weather systems (e.g., Nor’easters and Tropical Storms/Hurricanes).

California Current System (CUGN)

 

Equatorial Pacific Ocean (ROGER)

 

 

Doppler Current Profilers on Autonomous Underwater Gliders

With colleagues in the Instrument Development Group at Scripps, we have led efforts to use small acoustic Doppler current profilers (ADCPs) to estimate absolute horizontal velocities from gliders. Unlike geostrophic current estimates that are routinely made using glider observations of temperature, salinity, and depth averaged currents, ADCP-derived current estimates are available for each glider dive and in both horizontal directions. In equatorial regions, ADCPs on gliders allow us to measure the vertical structure of currents where the geostrophic estimates cannot be used due to the vanishing of the Coriolis parameter. We have also shown that ADCP measurements can be used to correct for the effects of biofouling-induced drag on glider-based estimates of depth averaged currents. Results from this work have been published in Todd et al. (2011, J. Geophys. Res.; 2017, J. Atmos. Oceanic Technol.).


 

Research in our group has been generously supported by the Office of Naval Research (ONR), National Science Foundation (NSF), National Oceanic and Atmospheric Administration (NOAA), Eastman Chemical Co., and WHOI.