SAN FRANCISCO - Typhoons,
the violent storms that are the bane of life across much of Asia, are a
boon for life at sea, where the cyclones stir up the nutrients that
microscopic algae crave, scientists said Saturday.
Scientists in Taiwan and the United States recently used a trio of
NASA satellites to observe how the passage of even moderate typhoons
over the South China Sea can generate upwellings of nutrient-rich water
from deeper in the ocean and spark massive blooms of phytoplankton.
"It's a natural hazard, it destroys life, but what I am showing is
it also enhances life," said Timothy Liu, a senior research scientist
at the National Aeronautics and Space Administration's Jet Propulsion
Laboratory in Pasadena.
Through photosynthesis, the algae absorb carbon dioxide from the
atmosphere and convert it to oxygen, offsetting emissions of carbon
dioxide from the burning of fossil fuels. The algae are also an
important food source for marine life.
Liu, working with research scientist I-I Lin of Taiwan's National
Center for Ocean Research in Taipei, combined data culled from three
satellites to show the positive effects of storms on marine life. They
presented their results Saturday at the fall meeting of the American
"Typhoons were completely neglected before, because it was impossible to quantify" their effect on the algae, Lin said.
Typhoon Kai-Tak passed over the South China Sea on July 5, 2000,
lingering for four days before traveling northward over Taiwan, based
on data acquired from NASA's Quikscat, a satellite that measures wind
speeds over water.
In its aftermath, sea surface temperature measurements made by the
joint U.S.-Japanese Tropical Rainfall Measuring Mission satellite
showed a 16-degree Fahrenheit drop in the area where the
counterclockwise-spinning storm had been parked. Colder water, drawn
upward by the typhoon, caused the drop, Lin said.
By July 12, 2000, four days after the typhoon had moved on, a third
satellite, the Sea Viewing Wide-Field-of-View Sensor, began to measure
a dramatic change in the ocean color that matched in extent the
previously observed cold spot. A 300-fold increase in ocean
chlorophyll, contained in the algae, accounted for the color change,
The bloom persisted for a month.
Liu and Lin said they tracked about 20 typhoons that swept the South
China Sea over the course of 2000 using the novel three-satellite
"The hypothesis was there, but there was no evidence to tie it together," Liu said of the typhoon-phytoplankton connection.
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