Research


Measuring the TKE budget and turbulent momentum flux beneath breaking waves using an autonomous underwater vehicle

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Field Testing of Hydroid-Kongsberg 600 AUV, Callinectes, instrumented with turbulence array 

Collaborators: N. Nidzieko (UCSB)

Surface gravity waves are the principal pathway through which momentum and mechanical energy are transferred from the atmosphere to the ocean and so play a key role in structuring turbulent mixing beneath the water surface. While considerable advances have been made in understanding wave-driven turbulent mixing in recent years, much is still unknown about the specific nature of momentum and energy exchange near the ocean surface. The COAST Lab has received an NSF grant to study wave-driven turbulence using a Hydroid Kongsberg 600 AUV instrumented with an array of fast-sampling turbulent sensors to characterize the specific nature of wave-driven mixing in the coastal ocean. We are currently gearing up for field work to begin in early 2019.

 


AUV observations of turbulent mixing in the far-field of the Chesapeake Bay outflow plume

 

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Fisher et al published in Geophysical Research Letters!

Collaborators: N. Nidzieko (UCSB), M. Scully (WHOI), R. Chant (Rutgers), P. Mazzini (SFSU)

The impact of a river plume on coastal ecosystems depends on the entrainment of ambient seawater through turbulent mixing; so detailed observations of the rates and mechanisms of mixing are essential to understanding the fate of river-borne materials on coastal shelves. We investigated turbulent exchange within the far-field of the Chesapeake Bay outflow plume during the transition to upwelling using turbulent microstructure measurements collected by a Hydroid-Kongsberg REMUS 600 autonomous underwater vehicle. These novel measurements illustrate the complexity of scalar mixing in the plume during the transition to upwelling and represent some of the most detailed observations to-date of a far-field plume.

 


Surface wave effects on air-sea momentum transfer and vertical mixing in the Chesapeake Bay, USA

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Deployment of turbulence tower in the Chesapeake Bay (photo credit Larry Sanford)

Collaborators: L. Sanford (UMCES-HPL), M. Scully (WHOI), W. Boicourt (UMCES-HPL), M. Li (UMCES-HPL), and C. Friedrichs (VIMS)buoy

As part of a collaborative investigation of wind-driven estuarine physics, my doctoral research, with L. Sanford at the University of Maryland Center for Environmental Science Horn Point Laboratory, focused on the effects of surface gravity waves on turbulent air-sea momentum transfer and vertical mixing in the Chesapeake Bay. An instrumented turbulence tower deployed in the middle reaches of the bay enabled a direct investigation of the local air-sea momentum budget, characterization of wind stress spatiotemporal variability and wave-dependence, and the specific nature of turbulent diffusive transport beneath breaking waves.

 


Biological-Physical Interactions in Estuaries: the role of wind in ecological functioning

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R/V Hugh R. Sharp

In addition to my core physical interests, I have been fortunate to contribute to interdisciplinary work that focused on the role of wind in controlling greenhouse gas exchange and hypoxia development in coastal systems. Specifically, winds play an important role in regulating the hypoxic volume in the Chesapeake Bay and in triggering nitrous oxide production through episodic injection of oxygenated water into the hypoxic zone.

 

 


Methods for Filling Gaps in Hydrological Data collected in Complex Terrain

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Columbia Icefield – Jasper, Alberta, Canada.

Collaborators: J. Lundquist (UW), B. Henn (UW), and M. Raleigh (UW).

Missing data are a common problem in meteorological and hydrological observational records, due to interruptions in transmission or instrument failure. Data gaps can have significant consequences for hydrological analysis and forecasting, especially when used as forcing conditions in numerical simulations. As an undergraduate researcher and member of the Mountain Hydrology Group at the University of Washington, I contributed to an investigation of methods used for filling spatiotemporal gaps in air temperature records collected in the complex terrain of the Sierra Nevada.