The Atlantic Ocean becomes a meteorological mixing bowl
from June 1 to November 30, replete with all needed
ingredients for a hurricane recipe. NASA turns to its cadre
of satellites to serve up a feast of information to the
forecasters who seek to monitor and understand 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, 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 Nino and La
Nina events, which respectively tend to suppress and enhance
Atlantic and Gulf hurricane development.
Thirty years ago, meteorologists were unable to see the
factors in hurricane formation and could only spot a
hurricane with still pictures from the TIROS-N satellite.
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 to enhance forecasts, providing data to
researchers several times a day.
The first ingredient in the hurricane recipe is sea surface
temperature of at least 82 F. Unlike traditional infrared
satellite instruments, the Aqua satellite’s Advanced
Microwave Scanning Radiometer (AMSR-E) and the Tropical
Rainfall Measuring Mission’s (TRMM) 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 Jason-1 satellite
altimeter 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 SeaWinds instruments aboard Japan’s Midori
2 and NASA’s 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
Atmospheric Infrared Sounder (AIRS) experiment suite aboard
the Aqua satellite obtains measurements of global temperature
and humidity throughout the atmosphere. This may lead to
improve weather forecasts, improved determination of cyclone
intensity, location and tracks, and the severe weather
associated with storms, such as damaging winds.
Rainfall intensity is the final ingredient, and the
Precipitation Radar provided by Japan for the TRMM satellite
provides CAT scan-like views of rainfall in the massive
thunderstorms of hurricanes. TRMM instruments probe young
tropical systems for rainfall intensity and the likelihood of
storm development. TRMM 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, TRMM provides
an inside view of how organized and tightly spiraled rain
bands are, key indicators of storm intensity.
TRMM provides tropical cyclone intensity information from the
safe distance of space allowing the National Oceanic and
Atmospheric Administration’s (NOAA) National Hurricane Center
and the Department of Defense Joint Typhoon Warning Center to
turn to TRMM, 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 the 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.
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