Abstract:

To investigate the characteristics and transport rules of cold air in different routes on heavy dust pollution weather in Ningxia， we summarize the circulation characteristics that are easy to cause heavy dust pollution weather in Ningxia on the basis of objective classification of daily ground circulation by using environmental and meteorological data and NCEP reanalysis data. Further， the weather characteristics， pollution sources and contribution rates of heavy dust pollution under the influence of cold air in different routes were analyzed by using the backward trajectory model. The results show that： （1） The cold air routes and circulation pattern that are easy to cause heavy dust pollution weather in the whole region are westward path （A， AN， ANW）， northwest path （AE， ANE， N， NE） and northward path （CE， CSE， E）. （2） Affected by the cold air along the westward route， Zhongwei was the first city to experience heavy dust pollution； Affected by the cold air along the northwest route， Zhongwei and Shizuishan first experienced heavy dust pollution； Affected by the cold air along the northward route， Shizuishan was the first city to experience heavy dust pollution. （3） Under the influence of cold air along the westward route and the northwest route， the transport track of dust in Ningxia was mainly west and northwest， and the dust sources were mainly from the gobi around Ejin Banner， Badain Jaran Desert and Tengger Desert， the contribution of sand source to the PM₁₀ mass concentration was 80-160 μg·m^-3 and above 160 μg·m^-3， respectively； Under the influence of cold air along the northward route， the transport track of dust in Ningxia was mainly northwest and northeast， and the contribution of Tengger Desert， Ulanbh Desert and Mu Us Sandy Land to the PM₁₀ mass concentration was above 140 μg·m^-3， among which， the contribution of the Mu Us Sandy Land in the easterly direction was above 160 μg·m^-3.

Key words: heavy dust pollution, circulation classification, transport rules