AOPE Research Overview
The Department of Applied Ocean Physics & Engineering pursues excellence by recruiting high-quality personnel, supporting their work, and advancing their careers. Following are research descriptions for selected AOPE staff who achieved milestones in 2012.
Figure 1: Results of Andone Lavery’s research, including (a) broadband acoustic backscatter from turbulent salinity microstructure at the density interface in the salt-stratified Connecticut Estuary; (b) remote acoustical inference of the corresponding dissipation rate of salinity variance, a quantitative measure of turbulent mixing; and (c) and (d) ground-truthing of the acoustical measurements against in-situ (MAST) measurements.
Sound in the ocean is scattered by waves, stratified turbulence, sediments, organisms and bubbles. Andone Lavery studies the physics of sound scattering and uses the scattered sound for remote sensing of oceanographic phenomena. Departing from narrowband acoustics, her research develops broadband techniques, analogous to viewing the ocean in “color”, for classification and quantification of scattering sources. She has applied these techniques to biology and to turbulent mixing in stratified estuaries. Her recent work has remotely quantified estuarine mixing at unprecedented range and resolution (Figure 1) and has led to a new understanding of stratified turbulence in strong flows. Andone was promoted to Associate Scientist with Tenure on March 8, 2012.
Figure 2: Results of Ying-Tsong Lin’s research, including (a) simulation of ocean temperature near the Hudson Canyon (courtesy of Gordon Zhang, AOPE); (b) corresponding depth-integrated intensity, showing sound focusing owing to reflection from the concave canyon floor; (c) a vertical section of transmission loss (TL) along the canyon axis, showing strong focusing in a narrow duct; and (d) and (e) vertical sections of TL across the canyon showing the detailed focusing pattern.
Sound in the ocean is refracted and reflected by strong gradients in the acoustical properties of the water column and seabed, producing complex spatial patterns that are important in scientific, industrial and military applications. Ying-Tsong Lin has led the development and application of three-dimensional acoustical simulations in complex environments, and has elucidated the acoustical effects of oceanographic and geological variability. For example, in a train of internal waves, ducts form between the wave fronts because of the gradients of sound speed associated with the ocean temperature, so that sound is trapped within the narrow ducts over long distances. Reflection from concave canyon floors similarly causes strong focusing in narrow zones (Figure 2). Ying-Tsong was promoted to Associate Scientist on October 10, 2012.
Figure 3: Equipment used in Anna Michel’s research, including (a) QC laser (photo courtesy Claire Gmachl Research Group, Princeton University); (b) QC laser CO2 isotope sensor for gaseous measurements (photo courtesy Sentinel Photonics); and (c) spectrometer, SO2 filled gas cell, and deep UV LED, currently being used to develop a highly sensitive SO2 sensor.
Anna Michel uses novel light sources to design and build new oceanographic sensors. She is currently adapting quantum cascade (QC) lasers, tiny mid-infrared sources (Figure 3a), to measure air-sea transport of carbon dioxide (CO2) and carbon isotopes of CO2 in estuaries (Figure 3b). In collaboration with other AOPE engineers, Anna is designing an sulfur dioxide (SO2) sensor (Figure 3c), which capitalizes on deep ultraviolet (UV) light- emitting diodes (LEDs), and will be sufficiently compact, robust, field deployable, inexpensive, efficient, and sensitive for long-term high-quality ship- and buoy-based measurements. Anna was appointed to Assistant Scientist on September 20, 2012.
Figure 4: From Chip Breier’s research, a high temperature black smoker hydrothermal plume from the Piccard vent field, in the Mid-Cayman Rise of the Caribbean, being sampled as part of a study of plume chemistry and microbiology interactions. Samples are being collected by in situ pumping using custom sampling equipment mounted on the remotely operated vehicle Jason II.
Using instruments that he develops and deploys on remotely operated vehicles (Figure 4), Chip Breier studies the chemical and particle-forming reactions that occur within deep-sea hydrothermal plumes. His goal is to understand the role of hydrothermal discharge on macro- and micro-nutrient concentrations in the modern ocean and ultimately through geologic time. His current focus is the understudied rising portion of hydrothermal plumes where particle formation begins. His results from the East Pacific Rise, Lau Basin and Mid-Cayman Rise reveal that the particle formation process is kinetically limited, and that previous predictive approaches miss the dominant presence of amorphous mineral phases. These results also suggest important interactions with organic matter and microbiology. Chip was promoted to Associate Scientist on October 10, 2012.
Figure 5: From Mike Purcell’s work, three REMUS 6000 AUVS ready for launch at the start of the search for the Air France Flight 447 plane lost in the mid-Atlantic. Each AUV swims approximately 125 km in 20 hours and then returns to the ship for four hours to download data, replace batteries, and upload instructions for the next mission.
Mike Purcell’s work advances the capabilities and applications of autonomous underwater vehicles (AUVs). The REMUS AUVs (Figure 5), developed in AOPE, are used by Navy and commercial and scientific investigators to accomplish varied tasks that require excellent stability, navigation, terrain-following, and coverage. Recently Mike and his colleagues have participated in operations to map fish schools, locate and image ancient shipwrecks, measure water properties and currents under sea-ice, track great white sharks, conduct scallop surveys, map the RMS Titanic wreck site, and locate an Air France passenger plane lost in the mid-Atlantic. Current research is directed toward integrating advanced sensors, expanding data processing and decision-making, and increasing mission endurance from days to weeks. Mike was promoted to Principal Engineer on December 20, 2012.
John Kemp has established and leads one of the premiere groups worldwide that support seagoing operations for WHOI and the broader oceanographic community. In recent work at the Russian-led Ice Camp Barneo, at the North Pole (Figure 6), the team deployed an Ice Tethered Profiler, an Arctic Ocean Flux Buoy, and a Seasonal Ice Mass Balance Buoy. Once at the camp, the team boarded a Russian MI-8 helicopter and flew an additional 30 miles over the Pole to increase the deployment duration before the systems drifted out of the Arctic. The effort is part of the North Pole Environmental Observatory. John was advanced to Group Operations Leader on May 20, 2012.
In addition to celebrating the above career milestones, the AOPE Department records with sorrow the passing of Mark Grosenbaugh on July 26, 2012. Mark made important contributions to the theory and practice of oceanographic mooring designs and to understanding the hydrodynamics of swimming organisms. Deeply committed to education, he advised students and post-docs, developed and taught courses, and held leadership positions in the MIT-WHOI Joint Program in Applied Ocean Science & Engineering. Mark was loved and admired by his many colleagues and friends in the oceanographic community.
—John Trowbridge, Department Chair
Last updated: November 18, 2013