Tropical Cyclone Heat Potential (TCHP) field in the Gulf of Mexico during
September 22, 2005. The path of Hurricane Rita is indicated with circles
spaced every 3 hours with their size and color representing intensity (see
legend). This hurricane intensified to category 5 as it traveled over the
Loop Current and a warm core ring (the finger of red and yellow). Rita
diminished to category 3 as its path went over a region of lower TCHP (and
cooler waters) outside the Loop Current and ring. The diamonds indicate
the National Hurricane Center predicted track and intensity as it makes
landfall, and are spaced by 24 hours. Altimeter data on NASA's Jason-1,
the US Navy's GFO, and the European Envisat satellites provide sea surface
height data used in generating the TCHP fields.
The Jason satellite carries a dual-frequency radar altimeter. This
instrument beams microwave pulses-at 13.6 and 5.3 Gigahertz,
respectively-downward toward the Earth. To determine the ocean's height,
the instrument precisely measures the time it takes for the microwave
pulses to bounce off the surface and return to the spacecraft. This
measure, multiplied by the speed of light, gives the range from the
satellite to the ocean surface.
The joint U.S.-French Topex/Poseidon mission is managed by the JPL for
NASA's Earth Science Enterprise, NASA Headquarters, Washington, D.C. JPL
is a division of the California Institute of Technology in Pasadena.
Research on Earth's oceans using Jason and other space-based capabilities
is conducted by NASA's Earth Science Enterprise to better understand and
protect our home planet. For more information on Topex/Poseidon, see
http://topex-www.jpl.nasa.gov.)
