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February 10, 2003
NASA Goes On-Line With Extra-Tropical Storm Tracks
If you're a weather fanatic, or if you?ve just ever wondered how stormy
it was around the world on the day you were born, you can now find out.
Scientists working with NASA have created a free on-line atlas that shows
extra-tropical storm tracks between 1961 and 1998.
"Although the atlas was originally developed for use by climatologists
investigating the impact of global warming on storms, the images and
data have also been used by fisheries, foreign meteorological services,
researchers tracking historic storms, and by teachers and students," said
Mark Chandler, a Columbia University geologist at NASA?s Goddard Institute
for Space Studies (GISS), New York City.
The on-line "Atlas of Extra-Tropical Cyclones 1961-1998" plots storm
paths and statistics by tracking atmospheric low-pressure centers at
sea level. The sea level pressures are calculated using data provided
by the National Centers for Environmental Prediction and the National
Center for Atmospheric Research (NCEP/NCAR) Reanalysis Project.
Fundamental information available about extra-tropical storm systems
includes maps of storm frequency and intensity as well as plots of individual
storms paths. In addition to the average intensity of storms over time,
maps of the "most severe" storms are also calculated.
The global maps include individual monthly and seasonal averages for
the years 1961 through 1998 and all frequency and intensity maps are
available as either rectangular maps or polar projections (which provides
a view of the tracks from both north and south poles). If a user chooses
to download "Tracks," a grayscale image of the world is presented showing
the tracks of all storms for the entire period selected. Together, the
images presented in this atlas describe the state of the mid- and high-latitude
storm tracks during much of the latter half of the 20th century.
In addition to images, the data is also available for download, along
with an associated FORTRAN computer program. The program can be used
to extract subsets of the database and places the information into report
form. The reports identify how long a storm lasted, the latitude and
longitude positions of storms at 12-hour intervals, the atmospheric pressure
at the storm center (low pressure suggests a storm), as well as the day,
month, year and time (Greenwich Mean Time).
Currently, NASA is working to update the Atlas to include data through
the year 2001 as well as data for the years 1950 through 1960. A CD-ROM
is also available, which includes GIF images of all frequency and intensity
maps, and higher resolution postscript images of the grayscale "tracks" maps.
Send requests to: Dr. Mark Chandler, NASA/GISS-CCSR, 2880 Broadway, New
York, NY 10025, email: mchandler@giss.nasa.gov.
To access the NASA/GISS storm tracks database:
http://www.gsfc.nasa.gov/topstory/2003/0211tropstorm.html
For more information and images, see:
http://www.gsfc.nasa.gov/topstory/2003/0211tropstorm.html
The NCEP/NCAR Reanalysis Project:
http://wesley.wwb.noaa.gov/reanalysis.html
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Contacts:
Rob Gutro
AMS Newsroom
(Phone: 562/628-8204)
NASA Goddard Space Flight Center
(Phone: 301/286-4044)
Stephanie Kenitzer
American Meteorological Society
Phone: 425/432-2192
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 The Frequency of Storms
During the Winter of 1982
In this image the greatest frequency of extra-tropical
storms (reds) can be seen to occur along the path of warm ocean currents
that follow the eastern seaboards of North America and Asia. These warm,
poleward-moving currents create a large temperature contrast with the
cold winter-time continents and supply energy that helps generate and
strengthen storm systems. Note that a similar pattern of storms circumnavigates
the cold continent of Antarctica. The scale used for the frequency plots
represents the percent of time that a low pressure center (i.e. a storm)
was found over a give location during the period of examination - in
this case the 90 days from December 1, 1981 to February 28, 1982. CREDIT:
NASA Goddard Institute for Space Studies
 The Mean (Average) and
Most Severe Storm Intensity of the 1982 Winter
The intensity of storms in the atlas is defined by the
central pressure level of the cyclone - lower pressures represent more
intense storms. The "mean intensity" plots show the average central pressure
of all storms that pass over a region during the time period, whereas
the "most severe storm" plots show the lowest central pressure of any
storm that crossed a region. In these maps (shown as polar projections)
the plots show that the strongest storms (red-purple) follow the warm
ocean currents along the continental margins. In the Northern Hemisphere
the storms tend to increase in severity as they traverse poleward, picking
up energy as they go, until finally dissipating over the cold high latitudes.
In general, the winter has more intense extra-tropical storms, because
larger temperature contrasts exist between the continents and oceans
during winter. CREDIT: NASA Goddard Institute for Space Studies
 Storm Tracks During the
Winter of 1982
This image shows the individual paths of all storms
between December 1, 1982 and February 28, 1982. Each dot represents the
position of a low pressure cell (area) at midnight or noon (Greenwich
Mean Time) and the lines connecting the dots indicate the projected path
of the storm. Storms lasting less than 36 hours (3 segments) are not
plotted. Looking at the U.S., most of the storms develop on the lee side
of the Rocky Mountains, where cool dry air from Canada mixes with warm
moist air from the Gulf of Mexico. CREDIT: NASA Goddard Institute for
Space Studies
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