DOI: 10.1007/s00382-015-2835-3
Scopus记录号: 2-s2.0-84942064178
论文题名: Mechanisms rectifying the annual mean response of tropical Atlantic rainfall to precessional forcing
作者: Tigchelaar M. ; Timmermann A.
刊名: Climate Dynamics
ISSN: 9307575
出版年: 2016
卷: 47, 期: 2017-01-02 起始页码: 271
结束页码: 293
语种: 英语
英文关键词: Atlantic ITCZ
; Nonlinear rectification
; Orbital forcing
; Precession
; Tropical precipitation
英文摘要: Numerous reconstructions of tropical hydroclimate in the Pleistocene display substantial variability on precessional timescales. Precessionally-induced insolation variations, with a mean period of ∼ 21 , 000 years, affect the strength of the seasonal cycle, but not annual mean insolation. The existence of variations in annual mean climate on precessional timescales therefore hints at the existence of nonlinear mechanisms that rectify the zero annual mean forcing into a non-zero annual mean response. The aim of this study is to identify these nonlinear rectification mechanisms. The traditional view of precessionally-forced precipitation changes is that tropical precipitation increases with summer insolation. By comparing two simulations with an earth system model (CESM1.0.3) we find that this paradigm is true for continental but not for oceanic changes in precipitation. Focusing on the Atlantic intertropical convergence zone (ITCZ), we find that the continental temperature and precipitation response to precessional forcing are key rectifiers of annual mean precipitation over the ocean. A boundary layer response to temperature changes over northern Africa affects the meridional position of the ITCZ over the North Atlantic in boreal spring and summer, but not in fall and winter. Over the equatorial and South Atlantic, the intensity of precipitation is strongly impacted by diabatic forcing from the continents through an adjustment of the full troposphere. Although the top of atmosphere insolation forcing is seasonally symmetric, continental precipitation changes are largest in boreal summer, thus skewing the annual mean response. These results show that it is important to take into account the seasonality of climatic forcings, even when studying annual mean climate change. © 2015, The Author(s). Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/53639
Appears in Collections: 过去全球变化的重建
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作者单位: Department of Oceanography, University of Hawaii at Manoa, Honolulu, HI, United States; International Pacific Research Center, University of Hawaii at Manoa, Honolulu, HI, United States
Recommended Citation:
Tigchelaar M.,Timmermann A.. Mechanisms rectifying the annual mean response of tropical Atlantic rainfall to precessional forcing[J]. Climate Dynamics,2016-01-01,47(2017-01-02)