gravity and ocean currents

* * *

New View of Gravity Could
Unlock Secrets of Ocean Circulation

PASADENA, California, July
23, 2003 (ENS) - The first science project from the Gravity Recovery and

Climate Experiment (Grace)
mission - a joint project of the U.S. National Aeronautics and Space
Administration (NASA) and
the German Aerospace Center - has produced the most accurate map yet of
Earth's gravity field.

The data are expected to
significantly improve the ability to understand ocean circulation, which
strongly
influences weather and
climate, and this initial model is "a feast for oceanographers,"
according to Dr. Byron
Tapley, Grace principal
investigator at the University of Texas' Center for Space Research.

"This initial model
represents a major advancement in our knowledge of Earth's gravity
field," Tapley said.
"Pre-Grace models contained
such large errors many important features were obscured. Grace brings
the true
state of the oceans into
much sharper focus, so we can better see ocean phenomenon that have a
strong impact
on atmospheric weather
patterns, fisheries and global climate change."

The preliminary model was
created with 111 days of selected Grace data to help calibrate and
validate the
mission's instruments and
improves knowledge of the gravity field so much it is being released to
oceanographers now, months
in advance of the scheduled start of routine Grace science operations,
scientists
say.

Grace is the newest tool for
scientists working to unlock secrets of ocean circulation and its
effects on climate
and is providing a more
precise definition of Earth's geoid, an imaginary surface defined only
by Earth's
gravity field, upon which
the planet's ocean surfaces would lie if not disturbed by other forces
such as ocean
currents, winds and tides.

The geoid height varies
around the world by up to 200 meters (650 feet). Grace will allow
scientists to know
the exact geoid height with
centimeter-like precision, which will allow scientists to separate out
gravitational
effects on the ocean's
surface and improve the accuracy of satellite tools that measure sea
surface height,
ocean heat storage and
global ocean circulation.

Grace senses minute
variations in gravitational pull from local changes in Earth's mass by
precisely
measuring, to a tenth of the
width of a human hair, changes in the separation of two identical
spacecraft
following the same orbit
some 220 kilometers (137 miles) apart.

It will map the variations
from month to month, following changes imposed by the seasons, weather
patterns
and short term climate
change.

*
-- -Kraig Grady
North American Embassy of Anaphoria Island
http://www.anaphoria.com
The Wandering Medicine Show
KXLU 88.9 FM WED 8-9PM PST