NASA satellites zoom in on hurricanes
- News Release: 2003-121
September 10, 2003
NASA Satellites Sample Hurricane 'Ingredients' to Help Forecasters
Every year, from June 1 to November 30, the Atlantic Ocean becomes a
meteorological mixing bowl, replete with all the needed ingredients
for a hurricane recipe. Forecasters who seek to monitor and
understand hurricanes are increasingly turning to a cadre of NASA
satellites and instruments, including several from NASA's Jet
Propulsion Laboratory, Pasadena, Calif., that serve up a feast of
information on these awesome storms.
Typically, during the peak of hurricane season, from late August to
mid-September, tropical cyclones of interest to U.S. coastal regions
form around the Cape Verde Islands off Africa. NASA satellites are
critical for helping forecasters determine if all of the ingredients
are coming together to create a hurricane. If a hurricane forms, it is
critical to know how strong it may be, and which coastal communities
or sea lanes will be at risk.
NASA provides researchers and forecasters with space-based
observations, data assimilation and computer climate modeling.
NASA-sponsored measurements and modeling of global sea surface
temperature, precipitation, winds and sea surface height have also
improved understanding of El Niño and La Niña events, which
respectively tend to suppress and enhance Atlantic and Gulf hurricane
Thirty years ago, meteorologists were unable to see the factors in
hurricane formation and could only spot a hurricane with still
pictures from the Television Infrared Operational Satellite -
Next-generation (Tiros-N) spacecraft. Over the past 10 years, visible
and infrared satellite sensors were the workhorses for monitoring
hurricanes. Today, multiple NASA satellites exploit everything from
radar pulses to microwaves for the purpose of enhancing forecasts,
providing data to researchers several times a day.
The first ingredient in the hurricane recipe is a sea surface
temperature of at least 27.8 degrees Celsius (82 degrees Fahrenheit).
Unlike traditional infrared satellite instruments, the Aqua
satellite's Advanced Microwave Scanning Radiometer E and the Tropical
Rainfall Measuring Mission's microwave imager can detect sea surface
temperatures through clouds. This valuable information can help
determine if a tropical cyclone is likely to strengthen or weaken.
The joint U.S.-French Jason-1 satellite altimeter, managed by JPL,
provides data on sea surface height, a key measurement of ocean energy
available to encourage and sustain hurricanes.
Another necessary ingredient is rotating winds over the ocean's
surface, precursors to tropical cyclone development. The
NASA-provided and JPL-built and managed SeaWinds instruments aboard
Japan's Midori 2, and NASA's Quick Scatterometer (QuikScat) satellites
can detect these winds before other instruments, providing even
earlier notice of developing storms to forecasters and scientists.
Air temperature and humidity are also important factors. The
JPL-managed Atmospheric Infrared Sounder experiment suite aboard the
Aqua satellite obtains measurements of global temperature and humidity
throughout the atmosphere. This may lead to improved weather
forecasts, improved determination of cyclone intensity, location and
tracks, and the severe weather associated with storms, such as
Rainfall intensity is the final ingredient, and the precipitation
radar provided by Japan for the Tropical Rainfall Measuring Mission
satellite provides computed tomography (CAT) scan-like views of
rainfall in the massive thunderstorms of hurricanes. The mission's
instruments probe young tropical systems for rainfall intensity and
the likelihood of storm development. The mission also sees "hot
towers" or vertical columns of rapidly rising air that indicate very
strong thunderstorms. These towers are like powerful pistons that
convert energy from water vapor into a powerful wind- and
rain-producing engine. Once a storm develops, the mission provides an
inside view of how organized and tightly spiraled rain bands are, key
indicators of storm intensity.
The Tropical Rainfall Measuring Mission provides tropical cyclone
intensity information from the safe distance of space, allowing the
National Oceanic and Atmospheric Administration's National Hurricane
Center and the Department of Defense Joint Typhoon Warning Center to
turn to it, QuikScat and other NASA satellites for early assessment of
storms in the open ocean.
The hurricane monitoring capabilities enabled by these satellites are
funded by NASA's Earth Science Enterprise, which is dedicated to
understanding Earth as an integrated system and applying Earth system
science to improve prediction of climate, weather and natural hazards
using the unique vantage point of space.
For more information and images on the Internet, visit:
http://www.gsfc.nasa.gov/topstory/2003/0909hurricane.html . The
California Institute of Technology in Pasadena manages JPL for NASA.