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China Meteorological Research Institute (中国气象科学研究院) 2021

The Impact of Biological Crusts on the Dust Emission Scheme in Asia

张健

Titre : The Impact of Biological Crusts on the Dust Emission Scheme in Asia

Auteur : 张健

Grade : Master 2021

Université : China Meteorological Research Institute (中国气象科学研究院)

Résumé partiel
The sand and dust storm is a catastrophic weather phenomenon that affects the world.In order to ensure the accuracy of sand and dust storm forecasts,accurate earth surface conditions are very important for dust emssion.There are many factors that affect the surface conditions.One of them is the surface biological crusts which have not been considered in most dust emission schemes.One reason is that there is no biological crust distribution that covers the sand source areas of Asia that can be used for sand and dust emission models.Another reason is that there is still a lack of quantitative research on how the crusts impacts on the dust emission.Therefore,in order to study the impact of crusts on sand emission,this thesis uses MODIS satellite surface reflectance data from 2000 to 2019 to invert the distribution of biological crusts in the source areas of sandstorms in Central and East Asia.And this paper also studies how the biological crusts impact on sand emission in source areas from the relationship between crust coverage,surface roughness and sand flux.The results show that biological crust is widely distributed in sand and dust source areas of Central and East Asia,with coverage rates of about 19.8% in Central Asian deserts,about 23.1% in the Gobi Desert,and about 17.3–32.8% in Chinese deserts.From the perspective of time change characteristics,There are two trends of the changes of biological crusts from “00 dust weather prevalence years” to “10 dust weather prevalence years” characterized by cyanobacteria crusts.One is in the deserts of Central Asia where cyanobacteria crusts are reduced in areas with high desertification,and cyanobacteria crusts with low desertification are increased.The changes in the deserts of Central Asia shows the deteriorating trend of the environment.The other is in Onqin Daga and Horqin sandy Areas where the crust of cyanobacteria in areas with low desertification is reduced,and the crust of cyanobacteria with high desertification is increased,showing a trend of improvement in the desert environment.

Mots clés : Retrieve of Biological Crusts ;Dust Emission Scheme ;Asian Sand and Dust Source ;Satellite Retrieval ;

Présentation (CNKI)

Page publiée le 2 mars 2022