The ocean is an equal if not dominant partner with the atmosphere in determining global climate. It modulates climate through heat storage and transport and through water mass modifications. Quantification of the ocean's role in climate through these processes requires a characterization of the complete spectrum of ocean velocity -- from large-scale mean flows that transport heat to small-scale intermittent turbulence that is the agent for mixed layer entrainment. Until quite recently, our picture of ocean currents came from the geostrophic calculation -- an indirect method that infers currents from density, as well as from a handful of measurements by direct techniques: current meters, surface drifters, and subsurface floats.
The World Ocean Circulation Experiment (WOCE) coincided with an exciting period for the development of direct current measurement technology. In particular, the widespread use of acoustic Doppler current profilers (ADCPs) represents a breakthrough in the measurement of ocean currents and a major advance in our capability to test hypotheses of dynamic processes occurring in the ocean. ADCPs have revolutionized the field of ocean current measurement in much the same way that CTDs revolutionized hydrography; instead of point samples, one obtains profiles of ocean currents. The shipboard ADCP measures profiles in the upper ocean from a ship underway; the lowered ADCP (LADCP) descends on the CTD package for a full ocean depth profile. This unique coverage in space and time, together with the vast dataset begun under the auspices of WOCE and continued under the Climate Varability (CliVar) program, means that there is now an unprecedented and growing database of ocean velocity measurements.
How will these measurements change our view of ocean circulation? What can we learn about flows not described by geostrophy: frictional boundary currents, internal waves, the wind-driven surface layer? Addressing these questions is the longterm goal of my research, and the ADCP is my primary tool. Follow the links under research interests or click on an image to see results from recent work.
Although I do not develop instruments, I enjoy the technical aspects of observational oceanography, and I find that a detailed understanding of the instrumentation is essential in interpreting the observations. The key challenge in making ocean observations is to design experiments for an extreme environment with only limited resources. For me, exploiting both ocean physics and measurement technique in order to formulate an experiment that can address a scientific hypothesis is both the most challenging and most rewarding aspect of being a sea-going physical oceanographer.