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Analysis of the ENSO signal in tropospheric and stratospheric temperatures observed by MSU, 1979-2000

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Calvo Fernández, Natalia and García, Rolando R. and García Herrera, Ricardo and Gallego Puyol, David and Gimeno Presa, Luis and Hernández Martín, Emiliano and Ribera Rodríguez, Pedro (2004) Analysis of the ENSO signal in tropospheric and stratospheric temperatures observed by MSU, 1979-2000. Journal of climate, 17 (20). pp. 3934-3946. ISSN 0894-8755

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Official URL: http://dx.doi.org/10.1175/1520-0442(2004)017<3934:AOTESI>2.0.CO;2


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Abstract

The El Niño-Southern Oscillation (ENSO) signal in the troposphere and lower stratosphere was investigated using Microwave Sounding Unit (MSU) data for the period 1979-2000. Empirical orthogonal functions (EOFs) were computed separately for zonal-mean and eddy temperatures in the Tropics and shown to provide a compact, physically intuitive description of ENSO that captures many of the details of its inception and evolution. Regressions of the MSU data on the principal components (PCs) of the tropical EOFs were then used to estimate the global signal of ENSO. The results show that ENSO accounts for over two-thirds of the temperature variability in the tropical troposphere, where its signature is composed of distinct zonal-mean and eddy patterns whose evolution is not simultaneous. In the tropical stratosphere, and outside the Tropics, ENSO explains a much smaller fraction of the variance (similar to10%), and manifests itself purely in the form of eddy anomaly patterns. The PCs of the eddy EOFs of the tropical stratosphere are almost perfectly correlated with those of the troposphere, suggesting that together the EOFs describe the vertical structure of equatorial waves. Volcanic eruptions and the quasi-biennial oscillation (QBO) are responsible for most of the variability (similar to87%) of the tropical lower stratosphere, and this variability is uncorrelated with ENSO; in the tropical troposphere, the effect of volcanic eruptions is detectable but small, accounting for about 3% of the variance.


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Additional Information:

© 2004 American Meteorological Society. The National Center for Atmospheric Research is sponsored by the National Science Foundation. We thank Jon Eischeid for his help in obtaining the MSU data used in this paper, and Henry Diaz, Dan Marsh, Bill Randel, and Anne Smith for discussions and suggestions on the original manuscript.

Uncontrolled Keywords:Sea-surface temperature; Quasi-biennial oscillation; Niño southern-oscillation; Northern-hemisphere; El-niño; Interannual variability; Circulation; Atmosphere; Anomalies; Pacific
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
Sciences > Physics > Atmospheric physics
ID Code:25665
Deposited On:04 Jun 2014 08:16
Last Modified:10 Dec 2018 15:05

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