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Nanjing University of Information Science and Technology (2020)

Reversal of Desertification in Qinghai-Xizang Plateau and Its Response to Abrupt Climate Change

蒋元春

Titre : Reversal of Desertification in Qinghai-Xizang Plateau and Its Response to Abrupt Climate Change

Auteur : 蒋元春

Grade : Doctoral Dissertation 2020

Université : Nanjing University of Information Science and Technology

Résumé
Desertification is one of the most serious ecological environment and social development problems in the world,and China is one of the countries most seriously affected by desertification.The Qinghai-Tibet Plateau is known as the"third pole"of the earth.Most of the areas have a cold and arid climate,and the ecological environment is fragile,which has the environmental conditions and potential factors for the occurrence and development of land desertification.The development of desertification in the plateau is closely related to climate change and vegetation change.Based on the temperature,precipitation and wind speed data of 81 stations in the Qinghai-Tibet Plateau from 1971 to 2013,the observation data of snow days on the Qinghai-Tibet Plateau from 1971 to 2016,the lower boundary of the first frozen layer,Landsat remote sensing image data of 1990,2000,2010 and 2015,normalized vegetation index(NDVI)and NCEP/NCAR reanalysis data from 1982 to 2015,this paper focuses on the change characteristics of vegetation(NDVI)and desertification land distribution on the Qinghai-Tibet Plateau.The climatic characteristics of climatic factors(air temperature,precipitation,wind speed)and underlying surface factors(snow,permafrost)and their relationship with vegetation change before and after the abrupt warming of the Qinghai-Tibet Plateau are studied.the relationship between the South China Sea summer monsoon and the plateau monsoon is analyzed,and the possible influence mechanism of the abnormal ending time of the South China Sea summer monsoon on the plateau winter climate is discussed,which has important scientific value for further scientific assessment of the impact of climate change.It has important practical significance for the construction of national ecological security barrier,the rational development and utilization of resources and the sustainable development of social economy.The main conclusions of this paper are as follows :(1)The study on the distribution of desertified land on the Qinghai-Tibet Plateau shows that from1990 to 2015,the desertified land on the Qinghai-Tibet Plateau showed an overall decreasing trend,and the area of desertified land decreased by 3 826 km2,equivalent to 0.96%of the desertified land area in 1990,with an average annual decrease of 153 km2.In particular,the desertification on the Qinghai-Tibet Plateau has been reversed continuously since 2000.(2)Under the background of global warming,the climate of the Qinghai-Tibet Plateau has changed significantly,from the cold and dry climate in the 1970s to the warm and humid climate in the middle and late 1990s.The macroscopic performance of the main meteorological elements from 1971 to 2013 is as follows :(1)Temperature.The plateau shows a consistent warming,with a warming range of 0.38℃/(10 a),which is higher than the global warming rate in the same period,especially in autumn and winter.

Mots clés : Reversal of Desertification ;Abrupt Climate Change ;Snow Permafrost ;South China Sea monsoon ;Qinghai-Xizang Plateau ;

Présentation (CNKI)

Page publiée le 21 octobre 2021