ISSN 1006-9895

CN 11-1768/O4

ENSO Signals in the Tropospheric and Stratospheric Temperatures: A Comparison among Different Datasets
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    Abstract:

    Signals of global tropospheric and stratospheric temperature anomalies associated with ENSO events in boreal winter during the period of 1980-1999 are investigated by using the Microwave Sounding Unit (MSU) data. Results derived from five reanalysis datasets (ERA40, JRA25, NCEP1, NCEP2, and MERRA) are compared with the MSU data. The symmetric and asymmetric components of temperature anomalies associated with warm and cold episodes of ENSO are revealed. The MSU data are taken as a benchmark to evaluate the veracity of ENSO signals described by different reanalysis datasets. The results show that, in the middle troposphere, the symmetrical components of temperature anomalies associated with ENSO feature a dumbbell-shaped pattern in the eastern Pacific, while the wave structures are evident, stretching from the Pacific to North America, with 3℃ maximum located in the eastern Pacific and northern North America; on the contrary, negative values turn up in the North Pacific, South Asia, and the South Pacific, with the minimum of -3.2℃ centered in southwestern China. The asymmetrical components are only evident in most of the high latitudes of the Northern Hemisphere. In the lower stratosphere, the symmetrical components of ENSO-related temperature anomalies are negative in the eastern Pacific, Greenland, and the North Atlantic, with the minimum -7℃ located in the North Atlantic. The positive values occupies the region north of 30°N during 70°W-70°E, with the maximum 6℃ centered in northeastern Russia. The asymmetrical components are obvious in the high latitudes of the Northern Hemisphere, and the maximum is 5.7℃. The reverse signals between the middle troposphere and the lower stratosphere are found in the equatorial eastern Pacific, the South Pacific, the North Pacific, southern China, Greenland, and some areas of the North Atlantic, while northern North America sees the same signals. Further studies indicate that temperatures averaged over 850-300hPa and 100-30hPa can well represent the ENSO-related signals in the middle troposphere and the lower stratosphere respectively.

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  • Received:
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  • Online: November 30,2011
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