Impacts of ENSO events on cloud radiative effects in preindustrial conditions: Changes in cloud fraction and their dependence on interactive aerosol emissions and concentrations

详细信息    查看全文

• 作者：Yang Yang ; Lynn M. Russell ; Li Xu ; Sijia Lou ; Maryam A. Lamjiri ; Richard C. J. Somerville ; Arthur J. Miller ; Daniel R. Cayan ; Michael J. DeFlorio ; Steven J. Ghan ; et al
• 刊名：Journal of Geophysical Research: Atmospheres
• 出版年：2016
• 出版时间：16 June 2016
• 年：2016
• 卷：121
• 期：11
• 页码：6321-6335
• 全文大小：9.5MB
• ISSN：2169-8996

文摘

We use three 150 year preindustrial simulations of the Community Earth System Model to quantify the impacts of El Niño–Southern Oscillation (ENSO) events on shortwave and longwave cloud radiative effects (CRE_SW and CRE_LW). Compared to recent observations from the Clouds and the Earth's Radiant Energy System data set, the model simulation successfully reproduces larger variations of CRE_SW and CRE_LW over the tropics. The ENSO cycle is found to dominate interannual variations of cloud radiative effects. Simulated cooling (warming) effects from CRE_SW (CRE_LW) are strongest over the tropical western and central Pacific Ocean during warm ENSO events, with the largest difference between 20 and 60 W m⁻², with weaker effects of 10–40 W m⁻² over Indonesian regions and the subtropical Pacific Ocean. Sensitivity tests show that variations of cloud radiative effects are mainly driven by ENSO-related changes in cloud fraction. The variations in midlevel and high cloud fractions each account for approximately 20–50% of the interannual variations of CRE_SW over the tropics and almost all of the variations of CRE_LW between 60°S and 60°N. The variation of low cloud fraction contributes to most of the variations of CRE_SW over the midlatitude oceans. Variations in natural aerosol concentrations explained 10–30% of the variations of both CRE_SW and CRE_LW over the tropical Pacific, Indonesian regions, and the tropical Indian Ocean. Changes in natural aerosol emissions and concentrations enhance 3–5% and 1–3% of the variations of cloud radiative effects averaged over the tropics.