Embargoed until 2 p.m. EST
NSF PR 02-29 - April 25, 2002
Satellite Data to Predict Plankton Blooms by Analyzing
Ocean Color
Scientists analyzing satellite data on ocean color
are gaining new insights into ocean productivity and
climate.
A green ocean is a productive ocean; the light from
the sun fuels the "bloom" of phytoplankton, tiny ocean
plants that turn the sea's surface a light green each
spring. This production in turn drives ocean food
webs. New research, published in the journal Science
on April 26, assesses the color of the ocean and finds
that it may yield clues about the relation between
marine ecosystems and the climate system. The research
was funded by the National Science Foundation (NSF).
David Siegel, a scientist at the University of California,
Santa Barbara, and colleagues analyzed ocean color
data from the satellite Sea-viewing Wide Field of
view Sensor (called "Sea WiFS") to address the factors
regulating the spring bloom of phytoplankton in the
north Atlantic Ocean. "The productivity of the ocean
[from blooms] is well established," said Siegel. "What
we don't know is how it gets recycled. We're trying
to get at how the ocean's biological pump works."
The biological pump is the mechanism by which carbon
dioxide is exported from the surface ocean into the
deep ocean via sinking particles, like the remains
of phytoplankton as they die off after blooms. It
is a critical factor in understanding global climate
change.
From the satellite is information Siegel and colleagues
were able to deduce the conditions required to start
a spring bloom: appropriate amounts of light reaching
down into the water column, a condition that occurs
when ocean waters "turn over" or mix, in spring.
"When viewed from space, the north Atlantic spring
bloom is among the largest mass greenings observed
on the Earth's surface," said Siegel. The blooming
progresses at speeds of 20 kilometers per day, leaving
a green wake in its path.
Jim Yoder, a co-author of the paper, on leave from
the University of Rhode Island Graduate School of
Oceanography and currently division director of ocean
sciences at the National Science Foundation said,
"We used satellite and other data to observe the start
of the phytoplankton growth period in the north Atlantic
Ocean, and we were able to explain the timing of the
spring growth period in the entire north Atlantic."
Previous research on spring blooms was done at sea
with microscopes and other tools. But by using satellites,
Siegel and Yoder were able to evaluate the process
using tens of thousands of data points, rather than
just a few.
One advantage provided by satellite ocean color data
is measurements that cover the entire north Atlantic
during all seasons and years. Such measurements, if
correctly interpreted, are a tool for studying natural
phytoplankton variability - an important characteristic
of marine ecosystems. The results of the present study
illustrate an approach for using satellite measurements
to study the year-to-year ecosystem variability associated
with changes to the climate system and to the location
and strength of ocean currents.
The research was also funded by NASA.
|