image: In this example of an Advanced Synthetic Aperture Radar image the gap winds and wind shadows, as well as filaments of strong winds extending seaward are visible. Vortices coming off the northern tip of Mindoro, Philippines, can also be observed. view more
Credit: Envisat/CSTARS at University of Miami
VIRGINIA KEY, Fla. — The Office of Naval Research (ONR) recently awarded a $3.75 million grant to support satellite based research studies on internal waves and typhoons in the western Pacific Ocean. As chairman of the University of Miami's (UM's) Division of Applied Marine Physics, and co-director of the Center of Southeastern Tropical Advanced Remote Sensing (CSTARS), Dr. Hans Graber will lead this effort and help to make substantial headway toward a better understanding of upper ocean dynamics, coastal processes, and electromagnetic and acoustic remote sensing of the ocean.
"We have a great deal of knowledge and data regarding hurricanes in the Atlantic Ocean and Caribbean Basin, so we're trying to translate that knowledge to typhoon prediction and observation," said Graber. "By looking into how typhoons react when they encounter major ocean currents, larger waves, topography of islands and archipelagos in the Western Pacific Ocean, and how these factors influence the strengthening of typhoons, we hope to be able to provide the support and resources necessary to advance current methods of storm modeling and disaster mitigation."
Administered over a period of three years, the ONR grant is helping to fund greater utilization of satellite data for a wide variety of projects; a crucial factor in understanding the generation mechanism and evolution of internal waves. Several experiments in southeast Asia are being conducted by scientists at UM's Rosenstiel School of Marine and Atmospheric Science, in collaboration with Taiwanese universities, to help to develop algorithms to more accurately specify the wind and wave fields in typhoons, and better characterize the morphology of super typhoons.
The project, entitled: Satellite SAR Exploitation and Imaging and Measurement of Oceanic Phenomena complements several ongoing projects within the Rosenstiel School involving Graber and co-investigators, including Drs. Michael Caruso, William Drennan, Roland Romeiser and Neil Williams, who are studying different aspects of cyclogenesis, air-sea interactions and internal wave properties. One goal of the new ONR project is to use CSTARS' unique capabilities to acquire global satellite data from a variety of satellite sensors and apply it to challenging issues of detection and characterization of internal waves, as well as their dynamics in straits and remote archipelagos where the deployment of in situ sensors may not be feasible.
"Internal waves in straits are generated by the interaction of tidal currents with sills in straits when the water is stratified by temperature and salinity, "said Graber. "When the wave trough of the internal tide travels faster than the crest, the wave steepens and transforms into an internal bore, which finally evolves into large solitary-wave packets some distance away. These wave packets are readily visible by satellite from space. Our ultimate goal is to assist in determining where these internal waves are generated and at what frequency and intensity so we can better predict the propagation and scattering of sound in these complicated geographic regions.
Another portion focuses on the uncertainty in observations and predictions of the propagation of sound in littoral regions, the vast area stretching from the coast out to areas of permanently submerged shoreline. Satellite observations can cover large areas with high enough resolution to characterize the presence and changes of a cold water dome forming northeast of Taiwan and the location of the Kuroshio Current which like the Gulf Stream has its own dynamics and generates eddies and intrusions of water onto the shelf. Together with the field observations satellite data will be used to directly assess the uncertainty relative to model predictions.
Graber and other scientists will also participate in ONR's newest research initiative on an improved understanding of the impact of typhoons on the Western Pacific Oceans. Using funding from a Defense University Research Instrumentation Program (DURIP) award the Rosenstiel team will be building two more air-sea interaction spar (ASIS) buoys for deployment in the path of typhoons. The ASIS buoys will be paired with Drennan's extreme air-sea interaction (EASI) buoy to measure ocean waves and the turbulence properties of surface and near-surface atmospheric and oceanic properties during the passage of typhoons and describe fluxes in and out of the water. These measured fluxes and sea state are critical parameters for numerical weather forecast and ocean wave models and help to improve prediction of tropical cyclone intensities.
About the University of Miami's Rosenstiel School
Founded in the 1940's, the University of Miami's Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life. For more information, please visit www.rsmas.miami.edu