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Influence of Saharan Dust on the Large‐Scale Meteorological Environment for Development of Tropical Cyclone Over North Atlantic Ocean Basin
Journal of Geophysical Research: Atmospheres ( IF 4.4 ) Pub Date : 2020-11-17 , DOI: 10.1029/2020jd033454
Yue Sun 1 , Chuanfeng Zhao 1
Affiliation  

The tropical cyclones (TCs) frequently occur in the North Atlantic Ocean Basin, which is adjacent to West Africa, the largest global source of atmospheric dust. However, few studies have conducted systematic observational research of how dust affects the genesis conditions of TCs at large scales which includes sea surface temperature (SST), vorticity, vertical wind shear, and specific humidity. This study focused on the period from June–September in the years 2000 to 2018 to investigate the horizontal and vertical distributions of aerosol optical depth (AOD) (dust) and meteorological parameters. Dust can be transported at 600 hPa upward and is mixed well within the troposphere over land, while it is mainly distributed in the lower troposphere over the ocean. The SST is significantly suppressed by dust due to direct radiation effects, but the atmospheric temperature is warmer at 20–40°W between 700 and 850 hPa. The vertical distributions of temperature and specific humidity are similar. Dust decreases specific humidity in the lower troposphere over the ocean, especially in high AOD regions, but enhances midlevel moisture. Dust heats the lower troposphere and favors the development of convection and positive vorticity at heights of approximately 800–1,000 hPa. The warming effect of dust on the lower atmosphere over land and the nearby oceans results in strengthened West African monsoons and vertical wind shear. Thus, dust suppresses the SST and low‐level specific humidities and favors wind shear and positive relative vorticity, which further influence environmental conditions in the TC genesis region.

中文翻译:

撒哈拉尘埃对北大西洋海盆发展热带气旋的大规模气象环境的影响

热带气旋(TCs)经常发生在北大西洋海盆,该海盆与西非(全球最大的大气尘埃来源)相邻。然而,很少有研究对尘埃如何影响TCs的成因条件进行系统的观测研究,这些条件包括海面温度(SST),涡度,垂直风切变和比湿度。这项研究的重点是2000年至2018年6月至9月,研究了气溶胶光学深度(AOD)(粉尘)的水平和垂直分布以及气象参数。尘埃可以在600 hPa处向上传输,并在对流层内陆地上充分混合,而粉尘主要分布在海洋的对流层下部。由于直接的辐射效应,粉尘可以极大地抑制SST,但是大气温度在700至850 hPa之间为20–40°W。温度和比湿的垂直分布相似。灰尘会降低海洋对流层下部的比湿度,特别是在AOD较高的地区,但会增加中层湿度。尘埃加热低层对流层,有利于在约800–1,000 hPa的高度发展对流和正涡度。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。温度和比湿的垂直分布相似。灰尘会降低海洋对流层下部的比湿度,特别是在AOD较高的地区,但会增加中层湿度。尘埃加热低层对流层,有利于在约800–1,000 hPa的高度发展对流和正涡度。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。温度和比湿的垂直分布相似。灰尘会降低海洋对流层下部的比湿度,特别是在AOD较高的地区,但会增加中层湿度。尘埃加热低层对流层,有利于在约800–1,000 hPa的高度发展对流和正涡度。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。特别是在AOD较高的地区,但会增加中等水平的水分。尘埃加热低层对流层,有利于在约800–1,000 hPa的高度发展对流和正涡度。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。特别是在AOD较高的地区,但会增加中等水平的水分。尘埃加热低层对流层,有利于在约800–1,000 hPa的高度发展对流和正涡度。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。灰尘对陆地和附近海洋低层大气的变暖作用导致西非季风增强和垂直风切变。因此,灰尘抑制了SST和低水平的比湿度,有利于风切变和正相对涡度,这进一步影响了TC成因区的环境条件。
更新日期:2020-12-01
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