Tuesday, September 29, 2009

Storm killers: Earth scan lab tracks cold water upwellings in Gulf of Mexico

Science Daily: Complex interactions between the ocean and overlying atmosphere cause hurricanes to form, and also have a tremendous amount of influence on the path, intensity and duration of a hurricane or tropical weather event. As researchers develop new ways to better understand and predict the nature of individual storms, a largely unstudied phenomenon has caught the attention of scientists at LSU’s Earth Scan Laboratory, or ESL. Cool water upwellings occurring within ocean cyclones following alongside and behind hurricanes are sometimes strong enough to reduce the strength of hurricanes as they cross paths.

“Ocean cyclones are areas of upwelling, meaning that cold water is not far from the surface as compared to the water surrounding it,” said Nan Walker, ESL director. “The Gulf of Mexico is full of ocean cyclones, or cold water eddies, many of which move rapidly around the margin of Gulf’s Loop Current, which is the main source of water for the Gulf Stream.”

While the upwelling is important to Gulf fisheries because it delivers nutrients into the surface waters, causing algal blooms and attracting marine life to the areas, oceanographers have recently begun to realize that these cyclones intensify currents near the surface and along the bottom of the ocean in areas of gas and oil exploration.

“Now,” Walker added, “our research has shown that ocean cyclones also provide temperatures cold enough to reduce the intensity of large Gulf of Mexico hurricanes.”…“Cool wakes are most beneficial when the storm occurs later in the season because the Gulf doesn’t warm as rapidly in fall and may not have time to warm back up,” said Walker….

Ivan (2004) in the Gulf of Mexico. At this point it was a tropical storm