With more than 70 percent of the Earth’s surface covered in water, studying ocean topography is vital to researchers who produce atmospheric models for forecasting hurricanes, optimizing commercial shipping routes, tracking floating debris and helping manage marine animal populations.
To measure the surface height of oceans, scientists at The Ohio State University ElectroScience Laboratory (ESL) analyze satellite altimeter data. While these instruments produce highly accurate measurements, small but important errors occur because waves are not symmetrical: wide, shallow wave troughs reflect electromagnetic energy more strongly than the narrow, sharp wave crests.
Joel Johnson, Ph.D., a professor of electrical and computer engineering, and Praphun Naenna, a graduate research assistant, have leveraged Ohio Supercomputer Center (OSC) resources to correct an “electromagnetic bias” that reports surface levels that are too low.
“Our study uses a method for hydrodynamic simulations that can better capture these effects than models previous studies employed,” said Johnson. “This method, however, comes with far more computational burden, so we use supercomputing resources at OSC to produce a deterministic set of sea surface profiles and the corresponding altimeter pulse returns.”
To this point, the development of EM bias simulation tools has been completed, and the numerical results have been verified.
“The focus is now on using these tools to investigate the impact of various physical effects on the EM bias, including variations with the wind speed and the radar frequency, and also the influence of short scale roughness,” said Naenna.
Project lead: Joel Johnson, The Ohio State University
Research title: Monte Carlo simulations of altimeter pulse returns and the electromagnetic bias
Funding source: The Ohio State University