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Inner Mongolia University (2021)

Study of Impacts of Vegetation Variation on Regional Climate and Water Balance in Mu Us Sandy Land Based on Nurmerical Simulation

郑颖

Titre : Study of Impacts of Vegetation Variation on Regional Climate and Water Balance in Mu Us Sandy Land Based on Nurmerical Simulation

Auteur : 郑颖

Grade : Doctoral Dissertation 2021

Université : Inner Mongolia University

Résumé partiel
Impacts of land use and land cover change(LUCC) on climate change is one of the important contents of global change research.Terrestrial vegetation variation is an important characterization of LUCC,which can affect surface energy balance and water cycle by altering biogeophysical properties such as green vegetation fraction and surface albedo,then exerting an important effect on regional climate metrics and water balance.As the important component of national strategy of“Ecological Protection and High-quality Development of the Yellow River Basin”,the Mu Us Sandy Land is located in arid and semi-arid region where the eco-environment is particularly vulnerable and is sensitive to climate change.The region used to be one of the most severely desertified areas in our country.Since 2000,with the implementation of various ecological restoration projects,the vegetation conditions and the eco-environment of the Mu Us Sandy Land have been significantly improved.The region has become the most successful example of revegetation and reversing desertification.However,the biogeophysical impacts of large-scale vegetation variation on regional climate and water balance lack quantitative assessment,and need to be studied in depth.In this study,the Mu Us Sandy Land was chosen as a typical case.Firstly,based on the data of normalized difference vegetation index(NDVI),the spatiotemporal change of vegetation variation was detected,and the relative contribution of climate change and human activities was distinguished.Secondly,based on numerical simulation,WRF-Noah land-atmosphere coupling regional climate model was used to quantitatively evaluate impacts of vegetation variation on regional climate metrics such as air temperature and precipitation,and then the related biogeophysical processes and mechanisms were clarified.On this basis,impacts of vegetation variation on regional water balance were further evaluated.Finally,the potential impact of land surface evapotranspiration on regional precipitation was modeled from the perspective of extreme change in soil moisture,and then the relative importance of local land surface(e.g.,land surface evapotranspiration)and large-scale atmospheric processes(e.g.,external moisture transport)to precipitation was discussed by comparing with the impacts of external moisture transport on precipitation.This study can not only provide guidance for vegetation restoration and ecological construction in arid and semi-arid region,but also provide a reference for understanding of the attribution of local climate change,scientific response to climate change and development of adaptive strategies.The study is expected to enrich and perfect the basic theory of the relationship between vegetation and climate.The main results and conclusions are as follows:1.From 2001 to 2018,the area of region where has experienced a significant increasing trend(p<0.05)in growing season(May to September)NDVI accounts for about 86%of the Mu Us Sandy Land,with a rate of 0.049 decade-1.The significant improvement of vegetation conditions is jointly affected by climate change and human activities.

Mots clés : Vegetation variation ;WRF model ;Land-atmosphere interactions ;Regional water balance ;Mu Us Sandy Land ;

Présentation (CNKI)

Page publiée le 20 octobre 2021