1995-3, RELEASE: January 24, 1995 Contact: Joan Vandiver Frisch NCAR Media Relations (303) 497-8607; Fax 303-497-8610 E-mail: jfrisch@ncar.ucar.edu Dial-an-Expert and Topic Summary on Current El Ni–o Events BOULDERÑAtmospheric scientists with the National Center for Atmospheric Research (NCAR) in Boulder and the National Meteorological Center in Washington, D.C., agree that current weather conditions in parts of the United States, western South America and some Pacific Islands signal that another El Ni–o event is now in a mature stage. This has resulted in major drought in AustraliaÑalthough rain recently returnedÑand is probably a major factor in the recent California rains and floods. The El Ni–o/Southern Oscillation (ENSO), caused by the broadly understood interaction between the atmospheric circulation and the ocean over the Pacific, is one of NCAR's principal research topics. The El Ni–o events develop every few years and involve a Pacific basin- scale ocean warming of 1 to 2 degrees Celsius, which typically extends from the Peruvian coast to the International Date Line, spanning about 100 degrees of longitude, or one-quarter of the earth's surface. The changes in sea temperatures alter tropical weather patterns and can influence short-term climate over the globe through changes in the atmospheric circulation. These periodic changes are known as the Southern Oscillation. El Ni–o events have led to droughts in Australia, Indonesia, the Philippines, northeast Brazil and southern Africa, while causing excessive rainfall in Peru, Ecuador and the central Pacific. So far meteorologists have noted three types of weather anomalies over North America that characteristically accompany an El Ni–o episode: (1) above-normal rainfall in the southeastern United States and Gulf Coast, (2) above-normal temperatures in the Pacific Northwest, Alaska and western Canada, and (3) below-normal temperatures in the southeastern United States. Major ENSO events during the winters of 1940-41, 1982-83, 1992-93 and now 1994-95 have produced exceptionally wet weather along the West Coast and in the Southwest of the United States. But in more moderate ENSO events (e.g., the winters of 1986-87, 1987-88), very dry conditions have been the rule, contributing to the current five-year drought in California. During strong El Ni–os, sea-surface temperatures and tropical convection increase in the central Pacific east of the International Date Line and carry the jet stream in midlatitudes farther east than normal, so that the jet stream and associated storm tracks often extend to California. Learning to recognize El Ni–o signals is one of the special research areas at NCAR, a number of universities in the United States and Canada, and the National Weather Service's National Meteorological Center. Additional in-depth information on ENSO for filing stories is available by contacting the experts listed below. NCAR is managed by the University Corporation for Atmospheric Research under sponsorship of the National Science Foundation. ----El Ni–o experts at NCAR---- Kevin Trenberth (tel. 303-497-1318, e-mail trenbert@ncar.ucar.edu) and James Hurrell (tel. 303-497-1383, e-mail jhurrell@ncar.ucar.edu), NCAR; mechanisms and evolution of ENSO events over the past 100 years Michael Glantz, (tel. 303-497-8119, e-mail glantz@ncar.ucar.edu), NCAR; societal aspects of ENSO events, including the use of ENSO information in decision-making Gerald Meehl (tel. 303-497-1331, e-mail meehl@ncar.ucar.edu), NCAR; climate model simulation of ENSO El Ni–o experts at other institutions Timothy Barnett (tel. 619-534-3223, e-mail tbarnett@ucsd.edu), Climate Research Group, Scripps Institution of Oceanography, University of California, San Diego; forecasts of ENSO Mark Cane (tel. 914-365-8344, e-mail mcane@lamont.columbia.edu), and Stephen Zebiak (tel. 914-365-8597, e-mail steve@lamont.columbia.edu), Columbia University's Lamont-Doherty Geological Laboratory, Palisades, N.Y.; forecasts and modeling of ENSO Clara Deser (tel. 303-492-8522), Cooperative Institute for Research in the Environmental Sciences; historical description of ENSO Vernon Kousky (tel. 301-763-8227, e-mail wd52vk@sgi46.wwb.noaa.gov) and Gerald Bell (tel. 301-763-8227, e-mail wd52gb@sgi46.wwb.noaa.gov), Climate Analysis Center/National Meteorological Center, National Weather Service/National Oceanic and Atmospheric Administration, Washington, D.C.; up-to-date information and near real-time ocean models and climate forecasts of El Ni–o events James O'Brien (tel. 904-644-4581, e-mail obrien@coaps.fsu.edu), Department of Meteorology, Florida State University; forecasts and modeling of ENSO Eugene Rasmussen (tel. 301-405-5376, e-mail erasmu@atmos.umd.edu), Department of Meteorology, University of Maryland, and the Cooperative Institute for Climate Studies; climate forecasts of El Ni–o J. Michael Wallace (tel. 206-543-7390, e-mail wallace@atmos.washington.edu), Department of Atmospheric Sciences, University of Washington; analysis of El Ni–o observations during the last 100 years -The End-