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Lanzhou University (2021)

The Characteristics and Influencing Factors of Oasis Effect ——A Case Study in Hexi Oasis

别强

Titre : The Characteristics and Influencing Factors of Oasis Effect ——A Case Study in Hexi Oasis

Auteur : 别强

Grade : Doctoral Dissertation 2021

Université : Lanzhou University

Résumé partiel
In the context of global climate change and intensification of human activities,huge changes in land use and land cover have significant impacts on ecology and climate change at local,regional and global scales.The arid regions are fragile parts of terrestrial ecosystems,more sensitive to global climate change and human activities than any other places.Oasis is the unique landscape in arid region,and the essence of arid land.Although oasis occupies a small proportion in the area of arid land,it carries almost all the social and economic activities in the area and concentrates most of the natural productivity.Hexi oasis is the foundation for the survival and development of the people in Hexi region.The rational development and utilization of the oasis area is the key to realize the sustainable development and rural revitalization strategy of this region.Oasis effect is a unique climate feature formed by the flow of material and energy in oasis-desert system,which charactered by cooling island effect.The study of spatial-temporal characteristics at multi-scale and formation mechanism of oasis cooling effect is the key to the research on climate change and oasis sustainable development in arid area.Compared with the studies on urban heating effect,the distribution,formation mechanism and ecological benefits of oasis cooling effect are still the scientific problems to be solved.Based on the basic theories of ecology and geography,this study takes the oasis and its desert background of Hexi Corridor as the research area,and uses multi-source remote sensing observation and regional climate model numerical simulation to reveal the three-dimensional spatial and temporal characteristics of the cooling effect in arid oasis.Based on the inner biophysical model,the effects of surface parameters of different land cover and land use,such as reflectance,Bowen ratio and surface flux,on the oasis cooling island effect and the biophysical mechanism of its cooling phenomena were quantitatively analyzed.Firstly,multi-source remote sensing products were used as data sources to analyze the oasis cooling island characteristics of different patches in Hexi Corridor at daily,monthly and seasonal scales.Secondly,the dynamic downscaling method based on WRF model was used to simulate the continuous weather in summer and winter of the Oasis-Desert system in Hexi,and the two-and three-dimension characteristics of the temperature field,humidity field,wind field and energy field of the oasis effect were analyzed.Thirdly,based on high-precision remote sensing products,the relationship between oasis effect and key land surface parameters,such as land surface albedo and land surface evapotranspiration,was analyzed by linear regression,and the energy differences caused by land surface parameters were further discussed from the perspective of energy balance.Finally,the IBPM model is used to quantitatively analyze the energy difference caused by the difference of key surface parameters into the temperature forcing caused by the surface parameters including albedo,Bowen ratio and ground flux.

Mots clés : Arid Area ;Remote Sensing ;Oasis;Influencing Factors ;Oasis Effect ;

Présentation (CNKI)

Page publiée le 21 octobre 2021