Genetic Conditions of Sandstorms in the Hinterland of Taklimakan Desert

Sandstorm is a kind of catastrophic weather with great impacts on ecology and social economy.As a result of special natural conditions, the Tarim Basin is one important area in China where sandstorm occurs very frequently. Research working on sandstorm in the Tarim Basin before is primarily focusing on the verge of the Tarim Basin, but few of the works are about the sandstorm in the hinterland of the Taklimakan Desert.In order to understand comprehensively the law of sandstorm occurrence in the Tarim Basin, the genetic conditions of sandstorm in the hinterland of Taklimakan desert is to be disclosed by analyzing the data of sandstorms collected from 1997 to 2002 at Tazhong weather station.Results show that the abundance of dust substance is a prerequisite to the occurrence of sandstorm in most areas.But dust origin isn't the limiting factor of sandstorm occurrence in the inner part of the Taklimakan Desert.At the same time the precipitation in this area is too little to change the moisture of sand surface, so precipitation can't influence the abundance of dust substance.The occurrence of sandstorm primarily depends on wind force which can be represented by average wind speed and days of strong wind, but statistic results show that wind forces only weakly correlate with days of sandstorm, therefore there are still other factors influencing the occurrence of sandstorm.Air stability which can be figured by temperature and weather process is another important factor influencing sandstorm occurrence.It is found that the occurrence of sandstorm has a positive correlation with temperature because of unstable air mass near ground surface.Sandstorms mainly occur in spring and summer, rarely in autumn and w inter; furthermore, sandstorms occur more frequently in summer more than in spring.Sandstorms mainly occur in daytime especially in the afternoon, but only a few occur in nighttime.Precipitation is a key indicator of weather process in the hinterland of the Taklimakan Desert.Statistic results show that sandstorms occurrence has a positive correlation with monthly days and monthly amount of precipitations.Data indicate that the month with annual largest precipitation doesn't correspond with the biggest hours of sandstorm persistence, but with the lower than the maximum in a year.As a result, a large amount of precipitation has a restrained effect on the occurrence of sandstorm to some extends.From 1997 to 2002, annual precipitation and air temperature tend to increase, but sandstorm occurrence tends to decline.This phenomenon may be response to the decrease of weather process especially dry and cold air activity caused by global climatic change.In brief, because the environment in the hinterland of the Taklimakan Desert is very extreme featured by mobile sand surface, scarce precipitation, strong evaporation, the genetic conditions of sandstorms in this area are also very special and different from other areas.