The NASA aircraft in flight over the Alabama study
region. Click the image for more information about it.
story to find out more.
Earth's Water Cycle From Space To Improve Weather Forecasting
By Don Comis
March 1, 2004
Tom Jackson, a hydrologist with the
Agricultural Research Service's Hydrology and Remote Sensing Laboratory
in Beltsville, Md., is the lead scientist for validation of the data to be
collected by Hydros, a new satellite being developed by the National
Aeronautics and Space Administration (NASA).
By 2010, Hydros should be orbiting the Earth daily and providing an
unprecedented monitoring of the planet's water cycle.
Data from Hydros will feed into weather and climate models that currently
predict soil moisture for daily forecasts based on precipitation and other,
indirect measurements. In the future, these models will have real-time, direct
measurements of soil moisture from satellite sensors.
Soil moisture is among the top terrestrial environment measurements needed
by the U.S. Departments of Agriculture,
Transportation. Changes in soil moisture
drive the atmospheric circulation that spawns storms that bring rain to
farmers--and hazards to military and civilian aircraft and to land
vehicles--along with more general hazards, like flooding.
For more than a decade, ARS, NASA and other agencies have been testing soil
moisture sensors in Oklahoma for use on Hydros. They started in Oklahoma partly
because it has the easiest land to monitor from space: mostly bare in spring
and summer, and covered with only grass or wheat in winter.
In 2002, Jackson and colleagues began a series of annual Soil Moisture
Experiments (SMEX), starting with Iowa corn and soybean fields, where plant
cover is a little harder to see through.
SMEX03 focused on the most difficult land of all--forests--in Alabama,
Georgia, Oklahoma and Brazil. That campaign was typical of those conducted over
the years. The scientists tested sensors on satellites and airplanes and
compared sensor data to ground-level readings of moisture in plant leaves and
soil, as well as to readings from a permanent network of monitoring towers.
Read more about the SMEX03 campaign in the
March issue of
Agricultural Research magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.