Our weather system is chaotic, meaning that small uncertainties or
errors in initial weather observations grow over time to make the forecast
completely unpredictable. Chaos is a major reason why predicting the
weather a week from now is less accurate than predicting the weather
on the next day.
In efforts to improve weather forecasting, a multidisciplinary team
of physicists, meteorologists, and computer scientists has concluded
that the degree of chaos is different throughout the weather map at any given time. The
above figure shows a 36 hour forecast from March 5, 2000. According
to their analysis, the red areas are chaos "hotspots" in which
small changes in conditions are believed to magnify most quickly into
large perturbations in the weather. Making more meteorological observations
in these hotspots can help reduce forecasting errors, the researchers believe.
Average locations of chaos hotspots in forecasts from February 10,
2000 to July 30, 2000. Red denotes regions in which the hotspots tend
to appear. In the hotspot regions, good initial observations become
most crucial for reducing forecasting errors.
Reported by: D. J. Patil, Brian R. Hunt, Eugenia Kalnay, James A. Yorke,
and Edward Ott in the 25 June issue of Physical Review Letters.
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