AIRS

Frequently Asked Questions


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Q.  What is the impact of AIRS data on forecasting of weather disasters, and how are
weather and climate different?  

A.  AIRS data are ingested into the national weather forecasting centers worldwide
and have resulted in a significant increase in the accuracy of the medium range
forecasts. It is the function of the national centers to issue warnings of
severe weather as early as possible. They are caught on the horns of the
dilemma --- to issue a warning or not. A warning is a serious undertaking, for
it results in costly response activities which may also inconvience a large
population.

Severe weather phenomon are a common occurance on our dynamic planet. In
earlier times, areas in which these events occur were not heavily populated, and
so they went unremarked. Now, however, we have extended our settlements into
these danger zones, and the human and economic impact of the events is
magnified. With 24-hour news constantly on the lookout for stories with
emotional and visual impact, it may appear to the casual observer that
catastrophies are happening more often. There has been no detectable increase
in severe weather. Major, serious hurricanes have struck in the past (Florida
went through some very bad ones in the 1920s and 1930s), and there appears to be
periods of lesser and greater occurances that span decades. Huge tornado
outbreaks in the Midwest have also taken place in the past. Back in the 1950s
there were terrible typhoones in the Indian Ocean that caused major flooding and
death in Bangledesh and India. In the late 1950s there were terrible blizzards
in the West, so bad that aircraft were used to drop feed to starving cattle
trapped in the snowdrifts. There also appears to be a cycle of drought in the
Southwest that is of the order of 40 years in period. Do you remember he
stories from the mid-1970s from California, in which people were advised to
"flush their toilets once per day to conserve water"?

Weather is the day-to-day, highly variable environment in which we live.
Climate is a much longer term trendinging of the "average" weather. AIRS data
are being used to improve the weather forecasting and also to study the climate
over the lifetime of the mission. Weather fluctuates from day-to-day,
season-to-season, and even decade-to-decade. There have always been and will
continue to be frosts, droughts, floods, hurricanes, tornados, derechos,
baseball-sized hail, etc. It would be better if we avoided the most dangerous
localities for building, such as the flood plains of great rivers and barrier
islands (which move). Hopefully the information that we provide will be used in
urban and land use planning by civil authorities.

Weather can throw us a curve that causes economic impact severe enough that it
can last for a decade or two. Climate is a whole different kettle of fish. In
the past, climate change has moved whole populations, for it results in weather
patterns that persist for centuries or even millenia. Huge swaths of lands that
were once well-watered and fertile then become deserts. Forests become
grasslands, and dry area become wet. Really severe climate changes cause ice
ages. We are still technically in an ice age now, although the last major
incursion of glaciers occurred 10,000 years ago. The Earth has been much warmer
in the past.

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