Soon, hand-held devices that scientists are working on may detect the presence of aerosols in air above oceans. It works by measuring how light scatters as it strikes the particles.
The portable photometers have been developed by Alexander Smirnov, an AERONET (Aerosol Robotic Network) project scientist at NASA's Goddard Space Flight Center, Greenbelt, Maryland, and his team.
Aerosols, the tiny atmospheric particles that can have an outsized impact on the climate, are just as likely to be found in the air above the oceans as they are over land.
Yet, aerosols are scarcely measured over the oceans.
Now, Smirnov, who is leading a new effort called the Maritime Aerosol Network (MAN), will send researchers with portable photometers on oceanographic research cruises.
The hand-held devices can detect the presence of aerosols in air by measuring how light scatters as it strikes the particles.
Taking the measurements is relatively easy.
Several times a day, a researcher stands on a ship's deck when the sun is fully visible, points the instrument at the sun, and pushes a button. The photometer performs a series of scans within a few seconds.
Smirnov has arranged to have the have handheld photometers carried aboard more than 50 vessels, both commercial and research, from 12 countries since November 2006.
Initial results show that data from the portable photometers correspond well with permanent AERONET stations on select islands.
The initial efforts have produced a tantalizing observation.
"Aerosol concentrations over the oceans at the high latitudes are not as high as satellite measurements suggest they should be," said Smirnov. "We need to figure out why we're seeing this difference," he added.