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Satellite shows El Niño water vapor in atmosphere
January 27, 1998
(Top image - P49502)
This image shows differences in atmospheric water vapor relative
to a normal (average) year in the Earth's upper troposphere about
10 kilometers (6 miles) above the surface. The measurements were
taken by the Microwave Limb Sounder (MLS) instrument aboard
NASA's Upper Atmosphere Research Satellite (UARS). These data,
collected in late December 1997, show higher than normal levels
of water vapor (red) over the central and eastern Pacific which
indicate the presence of an El Nino condition. At the same time,
the western Pacific (blue) is much drier than normal. The
unusually moist air above the central and eastern Pacific is a
consequence of the much warmer than normal ocean waters which
occur during El Nino. Warmer water evaporates at a higher rate
and the resulting warm moist air rises and forms tall cloud
towers. In the tropics, the warm water and the resulting tall
cloud towers typically produce large amounts of rain. These data
show significant increases in the amount of atmospheric moisture
off the coast of Peru and Ecuador since measurements were made in
November 1997. The maximum water temperature in the eastern
tropical Pacific, as measured by the National Oceanic and
Atmospheric Administration (NOAA), is still higher than normal
and these high ocean temperatures are likely responsible for an
increase in evaporation and the subsequent rise in humidity.
(Bottom image - P49503)
This series of six images shows the movement of atmospheric water
vapor over the Pacific Ocean during the formation of the 1997 El
NiÒo condition. Higher than normal ocean water temperatures
increase the rate of evaporation and the resulting warm moist air
rises into the atmosphere altering global weather patterns. Data
obtained by the Microwave Limb Sounder (MLS) on NASA's Upper
Atmosphere Research Satellite (UARS), from late February 1997 to
late December 1997, show the movement from the western Pacific to
the eastern Pacific of high levels of water vapor (red) at 10
kilometers (6 miles) above the surface. Areas of unusually drier
air (blue) appear over Indonesia. December 1997 data also show a
rapid increase of water vapor off the coast of South America, the
result of very high water temperatures in that region.
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