The instrumental record of ENSO: 1840s to 2000

Todd Mitchell
JISAO, University of Washington

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Abstract

ENSO variability in the tropics from the late 19th century onward is documented, making use of three indices: sea surface temperature averaged over the central and eastern equatorial Pacific minus global-mean sea surface temperature; the sea-level pressure anomaly averaged over the eastern Indian Ocean; and a multivariate index constructed from sea-level pressure, surface winds, and rainfall anomalies over the tropics. These three ENSO indices vary synchronously on seasonal to annual time scales from 1870 onward, and on decadal time scales from the 1890 s onward. With few minor exceptions (largely in the extratropics) the structure of ENSO-related anomalies in global wind, temperature and precipitation fields has changed very little since the late 19th century. Nor is there convincing visual evidence of secular trends or changes in the frequency or amplitude of warm or cold episodes of the ENSO cycle.

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1 Feb, 2002
2 PM/ DSRC 1D 403
(Coffee at 1:50 PM)
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