JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. D8, 10.1029/2000JD000298, 2002
Evolution of El Niño - Southern Oscillation and global atmospheric
surface temperatures
Kevin E. Trenberth, Julie M. Caron, David P. Stepaniak, and Steve Worley
National Center for Atmospheric Research, Boulder, Colorado, USA
Received 27 December 2000; revised 29 August 2001; accepted 10 September 2001; published 24 April 2002.
The origins of the delayed increases in global surface temperature accompanying El Niño
events and the implications for the role of diabatic processes in El Niño-Southern Oscillation
(ENSO) are explored. The evolution of global mean surface temperatures, zonal means and fields of
sea surface temperatures, land surface temperatures, precipitation, outgoing longwave radiation,
vertically integrated diabatic heating and divergence of atmospheric energy transports, and
ocean heat content in the Pacific is documented using correlation and regression analysis. For
1950-1998, ENSO linearly accounts for 0.06olsiC of global surface temperature increase. Warming
events peak 3 months after SSTs in the Niño 3.4 region, somewhat less than is found in
previous studies. Warming at the surface progressively extends to about ±30o latitude with lags of
several months. While the development of ocean heat content anomalies resembles that of the
delayed oscillator paradigm, the damping of anomalies through heat fluxes into the atmosphere
introduces a substantial diabatic component to the discharge and recharge of the ocean heat content.
However, most of the delayed warming outside of the tropical Pacific comes from persistent
changes in atmospheric circulation forced from the tropical Pacific. A major part of the ocean heat
loss to the atmosphere is through evaporation and thus is realized in the atmosphere as latent
heating in precipitation, which drives teleconnections. Reduced precipitation and increased solar
radiation in Australia, Southeast Asia, parts of Africa, and northern South America contribute to
surface warming that peaks several months after the El Niño event. Teleconnections contribute to
the extensive warming over Alaska and western Canada through a deeper Aleutian low and stronger
southerly flow into these regions 0-12 months later. The 1976/1977 climate shift and the effects
of two major volcanic eruptions in the past 2 decades are reflected in different evolution of ENSO
events. At the surface, for 1979-1998 the warming in the central equatorial Pacific develops
from the west and progresses eastward, while for 1950-1978 the anomalous warming begins along
the coast of South America and spreads westward. The eastern Pacific south of the equator warms
4-8 months later for 1979-1998 but cools from 1950 to 1978.
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Hongjun Zhang:
zhangho@ucar.edu