However, actual observations from SRA are essential because "they tell us how the wave field - the height, length and direction of waves in a given area – actually varies with a hurricane's wind speed, size, and forward motion so that we can improve the performance of the models that disaster managers and structural engineers rely on for guidance," said C. These computer models allow wave behavior to be predicted at times and places where there are no observations. While the flight portion of the SRA hurricane research program concluded with the 2005 hurricane season, the data gathered continue to help researchers develop and improve ocean wave computer models that simulate hurricane-generated ocean wave height, dominant wavelength, and wave direction. As shown here, large storms contribute significantly to an island's landward migration, a process also known as "barrier island rollover." Increased water levels, large waves and strong flows remove sand from the beach and then deposit it on the bay-side of the island. For more information on these images visit United States Geological Survey (USGS) Credit: USGS/NASA EAARL ProjectĪnimation above: This animation includes 3-D views of island topography (images A-C), and a post-Katrina aerial photograph (image D). High Resolution of Image A, High Resolution of Image B, High Resolution of Image C, High Resolution Image of D. Images Above: Three-dimensional views of island topography (A-C), post-Katrina oblique aerial photograph (D) Those distances are then subtracted from the aircraft altitude to produce a sea-surface elevation map that is displayed on a monitor in the aircraft. The SRA measures waves by sweeping a radar beam across the ocean and measuring the distance to the sea at many points. Strong storms like Hurricane Bonnie in August 1998 - the first to be monitored by SRA - were found to produce severe ocean waves and dramatic changes in wave height and complexity over small distances. It captured unprecedented details on wave behavior that are helping improve sea height forecasts. The NASA Scanning Radar Altimeter (SRA), designed to take measurements of the changing wave height and structure in and around hurricanes, flew through many storms on a National Oceanic and Atmospheric Administration (NOAA) WP-3D aircraft from 1998-2005. Credit: USGSĪs part of its activities to better understand Earth’s dynamic climate, NASA research is helping to increase knowledge about the behavior of hurricane waves. The storm surge submerged the islands, stripped sand from the beaches, and eroded large sections of the marsh. The second image is of the same area on August 31, 2005, two days after Hurricane Katrina made landfall. The first image, taken in July 2001, shows narrow beaches, vegetated dunes, and marshes. Image right: The Chandeleur Islands, a north-south oriented chain of low-lying islands located east of New Orleans, were severely damaged by recent hurricanes.
And through storm surges of up to 30 feet the storms can demolish shoreline structures, erode beaches and wash out coastal roads. These storms also create enormous ocean waves that are hazardous to ships. A hurricane's fury can be relentless, from frightening winds, to torrential rains and flooding.
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