The Occurrence And Development Of Sand And Dust Weather In The Typical Area Of Southern Xinjiang, China

The sand and dust weather is one kind of disastrous weather, which can bring much disaster, not only influence local human suvrival and agricultural production, but also severely damage eco-environment and climate change. The occurrence and development of the sand and dust weather is the key point of sand disasters. A detailed analysis of the differences of spatial and temporal distribution characteristics and transmission path of sand and dust, it can identify the source, area and scope affected. This has important theoretical value and practical significance on reduce the harm of the dust and construction shelter forest system on the regional scale.In this paper, we based on a high incidence of sand and dust weather area of southern Xinjiang as an example. According to the topography and geomorphology, the study area is divided into five regions: Northern region(Kuqa, Aksu, Korla), South region(Hetian Yutian Minfeng), Eastern region(Ruoqiang, Qiemo), Western region(Kashi, Bachu, Shache) and Central region(Tazhong). This study use surface dust monitoring data and HYSPLIT trajectory model, quantitative analysis, the change of five regions in months from 2005 to 2014(the time of the dust weather, from March to November). The spatial and temporal variation characteristics about different intensity of sand and dust weather(dust, flying sand and dust weather), different transmission path of airflow and sand and dust, and the influence area of different regions were studied.1) There is a quite different between the average number of sand and dust weather days in each month in different regions, from high to low order followed by: Center> South> West > East > North, the differences among the same region is relatively small. Minfeng, located in southern, where sandstorm occurrence frequency is too high, followed Tazhong located in central and Ruoqiang and Qiemo located in eastern. High frenquency of flying sand weather occurrences in central Tazhong, there are most dust weather in the southern.2) Total number of sand and dust weather is on the decline with the increase of the month, and showed consistent seasonal changes, the sand and dust weather days in spring > summer > autumn, but there is a little difference of the number of the sand and dust weather between spring and summer in center as well as in south. Whereas the sand and dust weather mainly happened in spring instead summer in west, north and east. Different seasons and sand and dust weather intensity show different trends with the increase of the year(2005-2014), total number of sand and dust weather showed a trend of increase in the autumn(in addition to the central and northern down); Flying sand has increasing trend in the spring and autumn of east and the spring summer and autumn of south, other are decreased; Sandstorm decreased with increasing year in different regions.3) When the sand and dust weather occurs in different regions, the mainly three kinds of airflow transport route to close to the ground of the study area are northwest route(by torugart pass or wuqia pass to enter), north route(central tianshan mountain pass into) and northeast route(eastern tianshan into), and has great difference between different months. The west region(kashi) of airflow transmission path are northwest route(54%), northeast route(17%) and north route(13%); Southern regions(Hotan) mainly are the northeast route(57%), northwest route(23%), north route(17%) and southwest route(3%), southwest route only happened in March and April; Northern region(kuqa) mainly are the northeast route(37%), northern route(35%) and the airflow of southern desert; Eastern region(Ruoqiang) mainly are the northeast route(82%); Center region(Tazhong) mainly are northern route(19%) and northeast route(65%).4) Sand and dust transmission route have large difference among different regions, the ratio of transmission to the outside of southern Xinjiang is less; the southern region(Hotan) is the main impact area of sand and dust weather. When the sand and dust weather are happen in the southern region(Hotan), the main influence to the western kashi region(19%), near Hotan region(49%), Qiemo–Ruoqiang region(10%) and central Tazhong region(4%), the outside Xinjiang transmission route(18%) are Hotan-Ruoqiang-Qaidam-Lanzhou area, Hotan-Ruoqiang-Dunhuang-Badain Jaran Desert-(Beijing, Japan Sea, less) area, and Hotan-Kashi-Northwest Mountain-(northern Xinjiang or Kyrgyzstan). In the western region(Kashi), the main influence to the sourthern Hotan region(31%) and northern Aksu region(24%); the outside Xinjiang transmission route(45%) are Kashi-Taklimakan Desert(Badain Jaran Desert, Qaidam Basin and Beijing) area, Kashi-Kuche- Badain Jaran Desert area and turgart mountain pass(Kyrgyzstan, northern Xinjiang, Badain Jaran Desert area). In the northern region(Kuqa), the main influence to the western Kashi region(18%), sourthern Hotan region(19%) and central desert hinterland(40%); the outside Xinjiang transmission route(15%) are Kuche-Tianshan mountain pass-northern Xinjiang area, Kuche Xiaotang-Badan Jaran desert-(outer Mongolia or Japan) and Kuche-Xiaotang-the hinterland of the Taklimakan Desert-the Qaidam Basin(outer Mongolia). In the eastern region(Ruoqiang), the main influence to the sourthern Hotan region(30%) and eastern Qiemo region(29%); the outside Xinjiang transmission route(39%) are Ruoqiang-Qaidam Basin-Lanzhou-(Beijing or Japan sea) area and Ruoqiang-Dunhuang-Badain Jaran Desert-(Beijing or Japan). In the central region(Tazhong), the main influence to the sourthern Hotan region(86%) and western Kashi region(6%); the outside Xinjiang transmission route(8%) are Tazhong-Ruoqiang-Qaidam Basin area and Tazhong-Badain Jaran Desert-(Beijing or Mongolia).In this paper, a quantitative analysis of spatial and temporal flow transmission path differences on the Southern Xinjiang has been did, and it goes through well with the results previously correspondence. The quantitative analysis of effects region of different temporal and spatial dust weather has also been did to determine the mutual influence of sand dust weather in different areas. The study analysed the causes and process of Southern dust, providing the important theoretical support to the area sheltbelt forest system construction scientificly and reasonably.