Anthropogenic sulfate aerosol and the southward shift of tropical precipitation in the late 20th century

Abstract

[1] In this paper, we demonstrate a global scale southward shift of the tropical rain belt during the latter half of the 20th century in observations and global climate models (GCMs). In rain gauge data, the southward shift maximizes in the 1980s and is associated with signals in Africa, Asia, and South America. A southward shift exists at a similar time in nearly all CMIP3 and CMIP5 historical simulations, and occurs on both land and ocean, although in most models the shifts are significantly less than in observations. Utilizing a theoretical framework based on atmospheric energetics, we perform an attribution of the zonal mean southward shift of precipitation across a large suite of CMIP3 and CMIP5 GCMs. Our results suggest that anthropogenic aerosol cooling of the Northern Hemisphere is the primary cause of the consistent southward shift across GCMs, although other processes affecting the atmospheric energy budget also contribute to the model-to-model spread.

A review of droughts on the African continent: a geospatial and long-term perspective

“…Some of them also focus on anthropogenic factors, such as climate change, aerosol emissions, land use practices and resulting land-atmosphere interactions, contributing to drought inducing mechanisms (e.g. Dai, 2011Dai, , 2013Hwang et al, 2013;Lebel et al, 2009;Zeng, 2003). The review of these studies revealed that there are a number of factors contributing to inducing drought conditions.…”

Preferred response of the East Asian summer monsoon to local and non-local anthropogenic sulphur dioxide emissions

“…Subsequently, however, this cold and dry anomaly is advected into Asia, where it induces atmospheric and surface feedbacks over Asia and the Western North Pacific (WNP), which also weaken the EASM. In spite of very different perturbations to the local aerosol burden in response to Asian and European sulphur dioxide 1 3 , decadal changes in sensible heat flux over the Tibetan Plateau (Ding et al 2009;Duan et al 2013), anthropogenic aerosol (Xu 2001;Menon et al 2002;Huang et al 2007;Liu et al 2009Liu et al , 2011Chen et al 2012;Zhang et al 2012;Guo et al 2013;Hwang et al 2013;Jiang et al 2013;Ye et al 2013;Wang et al 2013;Zhou et al 2013;Polson et al 2014;Song et al 2014), and natural decadal variability (Lei et al 2011).…”

Land–Ocean Shifts in Tropical Precipitation Linked to Surface Temperature and Humidity Change

“…We concentrate on meridional mean change because a substantial literature on zonal mean change and its relationship to aerosol forcing and interhemispheric energy budget imbalance already exists (e.g., Yoshimori and Broccoli 2008;Scheff and Frierson 2012;Chiang et al 2013;Hwang et al 2013) and because GCM-simulated response is more obviously connected with asymmetries in surface properties caused by zonal variations in land fraction than in the zonal mean case. (We do make zonal mean results and maps available in the online supplemental information for reference.)…”