Assessment of the relationship between the combined solar cycle/ENSO forcings and the tropopause temperature

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• 作者：Alfred M. Powell Jr.^a ; ^{Al.Powell@noaa.gov} ; Jianjun Xu^b ; ^{Jianjun.xu@noaa.gov}
• 关键词：Tropopause temperature ; Solar cycle ; ENSO
• 刊名：Journal of Atmospheric and Solar-Terrestrial Physics
• 出版年：2012
• 期刊代码：41_13646826
• 类别：ear
• 出版时间：May, 2012
• 卷：80
• 期：Complete
• 页码：21-27
• 文件大小：628 K

摘要

The tropopause region of the atmosphere shows large variability over time and by region. The complex changes near the tropopause are not fully understood, especially in terms of interdecadal and interannual forcings. The purpose of this paper is to investigate forcings in the tropopause region by using microwave sounder observations and comparing the results to previous analyses.

On the basis of the satellite retrieved temperatures from the Microwave Sounding Unit (MSU) Channel 3 (CH3) measurements which began in 1981 and continue to the current time, this analysis will assess the solar forcing and the El Nino Southern Oscillation (ENSO) forcing within the tropopause layer (300-100 hPa). The temperature variability from the combined 鈥渄ownward鈥?solar forcing and the 鈥渦pward鈥?ENSO forcing have been investigated using wavelet, multiple linear regression and lag correlation analyses.

The results show that the temperature variability within the tropopause layer was dominated by 3.5-7 and 14-28 year oscillations. The temperature responses to the two forcings apparently depend on the location, season and time scale of the measurements.

The temperature response to solar forcing can be found over the Arctic and Antarctic zones in winter. On the interdecadal time scale, the temperature response to solar forcing was markedly amplified with a lag of 1-2 years or 5-7 years and was out of phase between the Arctic, and all other latitudes. Interestingly, the statistically significant response to solar forcing was only identified over the tropical central and western Pacific in summer.

The temperature response to the ENSO forcing is much stronger than the solar forcing based on the magnitude of the regression coefficients. A significant positive response occurs over most of the tropical ocean areas in winter and a negative temperature response is confined to the tropical western Pacific in summer. On the interannual time scale, the temperature response is observed within the tropical areas and reaches a positive maximum 4-5 months later, and can be identified up to 10 months later with statistically significant values. After 10 months, the response is negative.