Tuesday, 15 May 2001: 9:30 AM
Presentation PDF (2.3 MB)
Satellite-mounted radar scatterometers designed by NASA to quantify
surface winds over the ocean actually measure the relative motion
between the air and the ocean surface. Estimates of the wind stress
from conventional surface wind measurements are usually derived
neglecting ocean currents. However, when the relative motion is used,
the differences in the estimated stress can be as large as 50% near
the equator and may even reverse sign during an El Nino. This
assertion is supported by the strong relationship between the surface
currents measured by the Tropical Atmosphere-Ocean (TAO) array in the
Pacific Ocean and the differences between the winds estimated from
scatterometer data and those measured by TAO anemometers. The fact
that the scatterometer measures relative motion, and not wind alone,
makes scatterometer-derived stress a more accurate representation of
the boundary condition needed for both atmospheric and oceanic models
than stress fields derived neglecting ocean currents.
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