The elusive swirl of breezes called the Catalina Eddy,
responsible for helping cool the Los Angeles basin, is
captured in a new animation of sea-surface winds measured by
the SeaWinds instrument on NASA’s QuikScat satellite. During
the hot, dry summer months these gentle winds are welcomed
because they direct the offshore marine layer toward the Los
Angeles basin. Because the flow is more onshore than normal,
this cooling oceanic influence of the eddy has been described
as nature’s purifier or air-conditioner for Los Angeles. The
animation is online at:

Beta-SP copies of the video are available for
broadcasters by calling Xaviant Ford at (818) 353-4484.

While the Catalina Eddy, an atmospheric vortex or eddy
with a counter-clockwise rotation pattern, can occur in the
California Bight (the open ocean bay formed by the bend in the
coast between Point Conception to the north and San Diego to
the south) at any time of the year, it is most often seen
during May and June. It can develop when the winds from the
northwest along the Southern California coast are stronger
than normal and interact with the local coastal and land
topography, turning inland and creating a vortex.

Only about 200 kilometers (120 miles) in diameter, the
Catalina Eddy has not been well measured by scientists. The
eddy is actually too small to appear in current weather
forecast models and is sometimes too shallow to have a strong
influence on the cloud structure viewed by weather satellites.
But in this animation, the high-resolution capability of the
SeaWinds instrument has visualized its complete circulation.
This capability allows scientists to study these smaller-scale
wind events that can have such a profound impact on local

The SeaWinds on QuikScat project is managed for NASA’s Earth
Science Enterprise by NASA’s Jet Propulsion Laboratory, Pasadena,
Calif. More information about SeaWinds is available online at .

JPL is a division of the California Institute of
Technology in Pasadena.