Atmospheric Sounding Station, El Arenosillo observatory, Atmospheric Research and Instrumentation Branch, National Institute for Aerospace Technology (INTA), Mazagón, Huelva, Spain.
Universidad de Castilla-La Mancha, Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Ciudad Real, Spain.
Sci Total Environ. 2022 Sep 15;839:156268. doi: 10.1016/j.scitotenv.2022.156268. Epub 2022 May 25.
Airborne dust represents a hazard to the environment and human health. The outflow of air masses carrying dust from northern Africa, the world's largest active dust source, to the North Atlantic and Mediterranean regions is modulated by atmospheric conditions. However, how global warming-driven changes on atmospheric circulation have influenced North African air outflow in the recent past is not well understood. Here, we explore the Saharan air outflow from northwestern Africa over the 1980 to 2020 period. We find a decrease in the transport to the Atlantic Ocean and the Iberian Peninsula of -0.29 ± 0.16% dec and -0.66 ± 0.18% dec, respectively, and an increasing trend to the Mediterranean Sea (0.24 ± 0.18% dec) and Europe (0.60 ± 0.18% dec). The results indicate that the strengthening of the Atlantic high pressure system and the Saharan thermal low, both associated with the narrowing of the Intertropical Convergence Zone and the Hadley Cell expansion under global warming, could be favoring the Saharan outflow to the Mediterranean Sea and Europe in detriment of transport to the Atlantic Ocean. The results also show that present-day Saharan air arrives at these regions at higher altitudes and in shorter timescales than decades ago. This is associated to the increase in surface heating conditions in the Sahara, 0.41 ± 0.02 °C dec, that can inject air into windier upper atmospheric levels, thereby allowing higher and faster air transport. Our results suggest a change in the Saharan air outflow likely associated with global warming and with potentially significant implications for the temporal and spatial patterns of North African dust export.
悬浮尘埃对环境和人类健康构成危害。从世界上最大的活跃尘埃源——北非携带尘埃的气团流出到北大西洋和地中海地区的情况，受到大气条件的调节。然而，人们对全球变暖驱动的大气环流变化如何影响最近过去北非空气流出的情况了解甚少。在这里，我们探索了 1980 年至 2020 年期间来自北非西北部的撒哈拉空气流出情况。我们发现，向大西洋和伊比利亚半岛的输送量分别减少了-0.29±0.16%dec 和-0.66±0.18%dec，而向地中海和欧洲的输送量呈增加趋势（分别为 0.24±0.18%dec 和 0.60±0.18%dec）。结果表明，大西洋高压系统和撒哈拉热低压的增强，均与全球变暖下热带辐合带变窄和哈德利环流扩张有关，可能有利于撒哈拉空气向地中海和欧洲流出，而不利于向大西洋的输送。研究结果还表明，目前撒哈拉空气到达这些地区的高度更高，时间更短，与几十年前相比。这与撒哈拉地区表面加热条件的增加有关，0.41±0.02°C dec，这可以将空气注入更强劲的高层大气水平，从而允许更高和更快的空气输送。我们的研究结果表明，撒哈拉空气流出量的变化可能与全球变暖有关，并可能对北非尘埃输出的时间和空间模式产生重大影响。
