WASHINGTON - A change in the color of ocean waters could have a drastic effect on the prevalence of hurricanes, new research indicates. In a simulation of such a change in one region of the North Pacific, the study finds that hurricane formation decreases by 70 percent. That would be a big drop for a region that accounts for more than half the world's reported hurricane-force winds.
It turns out that the formation of typhoons as hurricanes are known in the region is heavily mediated by the presence of chlorophyll, a green pigment that helps the tiny single-celled organisms known as phytoplankton convert sunlight into food for the rest of the marine ecosystem. Chlorophyll contributes to the ocean's color.
"We think of the oceans as blue, but the oceans aren't really blue, they're actually a sort of greenish color," said Anand Gnanadesikan, a researcher with the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey. "The fact that [the oceans] are not blue has a [direct] impact on the distribution of tropical cyclones."
In the study, to be published in an upcoming issue of Geophysical Research Letters, a journal of the American Geophysical Union, Gnanadesikan's team describes how a drop in chlorophyll concentration, and the corresponding reduction in ocean color, could cause a decrease in the formation of hurricanes in the color-depleted zone. Although the study looks at the effects of a simulated drop in the phytoplankton population (and therefore in the ocean's green tint), recently-published research argued that global phytoplankton populations have been steadily declining over the last century.
Gnanadesikan compared hurricane formation rates in a computer model under two scenarios. For the first, he modeled real conditions using chlorophyll concentrations in the North Pacific observed by satellites. He then compared that to a scenario where the chlorophyll
|Contact: Colin Schultz|
American Geophysical Union