阿拉伯半岛沙尘时空分布特征及气象条件

通过对阿拉伯半岛地面90个气象站20年沙尘天气、AI指数及风场的时空分布特征结合气象条件分析,确定该区域沙尘天气的发生规律及传输路径.结果表明：永久多尘地区是半岛扬沙发生最频繁的区域,从2月开始扩张,并在6月达到最大.浮尘的时空分布与扬沙类似,但还存在希贾兹山脉北部和波斯湾沿岸的高值中心,3月与永久多尘地区的高值区连成一片,6~7月达到最大,然后开始收缩并分裂成几个小中心.AI指数存在一个像倒箭头的相对高值中心,其变化具有明显的单峰分布,强度和范围在6月最大.10~4月和5~9月半岛分别盛行顺时针、逆时针旋转的风向,它们将沙尘远程传输到下游地区.天气学分析表明,冷锋入侵半岛使得来自北方的冷空气快速锲入暖空气之下,是导致沙尘天气出现的主要原因;后向轨迹聚类分析显示,半岛存在3类传输路径,其重要性依次为西北方向撒哈拉沙漠的远程传输、反气旋风场将来自伊拉克或伊朗的沙尘远程传输和本地的沙尘源传输.

Spatial-temporal distribution characteristics of sand dust and meteorological drivers in the Arabian Peninsula

Based on the analysis of the spatial-temporal distribution of dust weather, the wind fields, and the AI(Aerosols Index) at 90 stations over the past 20 years, the occurrences and transport pathways of dust weather in this region are identified. Permanently dusty land was the source of most blowing sand weathers on the peninsula, beginning to expand in February and peaking in June. The distribution of floating dust was similar, but with another high-value center in the northern Hijaz Mountains, connecting with the high-value area of permanently dusty land in March, reaching its maximum area in June-July, after then shrinking and splitting into several small parts. The AI Index was distributed as a "down arrow" relatively high value center, with an evident unimodal distribution. The intensity and area of AI reached a peak in June. From October to April and from May to September, the wind direction in the peninsula respectively shifted clockwise and counterclockwise, driving dust transport downstream. Synoptic analysis showed that with the cold front invading the peninsula the cold air moved quickly from the north lifting the warm air, which was the main reason for the dust weather. The backward trajectory clustering analysis presented three transport routes over the peninsula, to the Sahara desert in the northwest direction, from Iraq or Iran by counter cyclone field, and the local transport.