TEMPERATURE RANGE NARROWING BETWEEN DAYTIME HIGHS AND NIGHTTIME LOWS, N
OAA REPOR
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--- NOAA 97-41
CONTACT: Patricia Viets FOR RELEASE 7/17/97
The temperature range between daytime high temperatures and nighttime low temperatures is decreasing for most parts of the world, a team of scientists reports in the July 18 edition of Science magazine.
The scientists, led by David R. Easterling of the National Oceanic and Atmospheric Administration's National Climatic Data Center in Asheville, N.C., studied data from 5400 observing stations around the world. The data cover 54 percent of the world's total land area; this is 17 percent more than available for previous studies.
The scientists report that maximum temperatures have increased over most areas with the exception of eastern Canada, the southern United States, portions of eastern Europe, southern China, and parts of southern South America. Minimum temperatures, however, increased almost everywhere except eastern Canada and small areas of eastern Europe and the Middle East. The gap between the highs and lows decreased in most areas, except over middle Canada, and parts of southern Africa, southwest Asia, Europe, interior Australia, and the western tropical Pacific Islands.
Seasonally, the strongest changes in the temperature gap were in the Northern Hemisphere winter; the smallest changes were in the Northern Hemisphere summer. These facts suggest that there is an element of a seasonal cycle in the changes.
The authors note that minimum temperatures in the Southern Hemisphere increased and postulate that increased cloudiness is contributing to this. They also note that urban effects on the narrowing temperature gap are negligible, and circulation variations in parts of the Northern Hemisphere appear to be related to the narrowing gap.
In addition to Easterling, the authors are: Thomas C. Peterson, Thomas R. Karl, both of the National Climatic Data Center; Philip D. Jones of the University of East Anglian, U.K.; Briony Horton, David E. Parker, Christopher K. Folland, of the Hadley Center, Meteorological Office, Berkshire, U.K.; M. James Salinger of the National Institute of Water and Atmospheric Research, Auckland, New Zealand; Vyacheslav Razuvayev, of the All-Russian Research Institute of Hydrometeorological Information, Obninsk, Russia; Neil Plummer of the National Climate Center, Bureau of Meteorology, Melbourne, Australia; and Paul Jamason of DynTel, Inc., National Climatic Data Center.
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