摘要
中东作为世界第二大沙尘源区,其沙尘的排放影响了从北美到南亚的众多人口稠密地区.在过去20年中,中东地区的沙尘活动呈现出明显的趋势转变,即在2010年左右,其趋势由增长变为下降.而目前造成这种趋势转变的原因尚不清楚.本研究结合多源数据分析和全球气候模式模拟,揭示了中东沙尘的年代际趋势转变与热带北大西洋海表面温度的变化密切相关.具体而言,偏暖的热带北大西洋产生了异常的局地纬向环流,促进了气流在热带北大西洋的上升和在中东的下沉.由此产生的地表高压和北部更强的沙马尔风为中东创造了炎热和干燥的环境,这都有利于沙尘的排放和运输.因此,2010年前后热带北大西洋趋势由正转负是中东沙尘趋势变化的主要原因.该机制对预测中东地区的年代际沙尘变化乃至全球环境都具有重要意义.
The Middle East,as the world's second-largest dust source region,has dust emissions that significantly impact numerous populated areas,extending from North America to South Asia.Over the past two decades,dust activity in the Middle East has exhibited pronounced variability,with a notable trend shift from positive to negative around 2010.The underlying cause of this trend shift remains elusive.In this study,we employ multi-source datasets and global climate model simulations to demonstrate that the variability of Middle East dust activities is closely tied to changes in North Tropical Atlantic(NTA)sea surface temperature(SST).Specifically,a warm NTA SST anomaly generates an anomalous regional zonal cell characterized by ascending air motion above the NTA and descending air surrounding the Middle East.The associated surface high pressures around the Middle East subsequently induce hot and dry conditions accompanied by intensified Shamal winds in the north,which are favorable for dust emission and transport.The shift in SST trends from positive to negative in the NTA around 2010 is therefore responsible for the observed dust trend shift in the Middle East.This mechanism holds vital implications for predicting decadal dust variability over the Middle East region and further the project of global environment.
作者
刘冠宇
李婧
应同
Guanyu Liu;Jing Li;Tong Ying(Department of Atmospheric and Oceanic Sciences,School of Physics,Peking University,Beijing 100871,China)
基金
supported by the National Natural Science Foundation of China(41975023 and 42175144)。
