Study On The Impact Of Urbanization And Land Use/Cover Change On DTR

At present,the process of urbanization is carried out rapidly around the world.The expansion of the city has made great changes in land use/cover,disrupting the stability of the ecosystem and leading to the global climate change.It is necessary to carry out a comprehensive study on the land use/cover,urbanization and surface DTR(Diurnal Temperature Range)to provide a theoretical basis for coping with climate change.This paper took the district of Xuzhou as the study area,selected the MODIS surface temperature product data of 5 phases for 2003-2016 years to obtain the interannual and four seasonal DTR of the study area,analyzed the temporal and spatial variation characteristics of the surface DTR of the study area.The land use/ cover classification of the study area was carried out by the random forest classification method based on the Landsat series data,a quantitative study was conducted to ascertain the urbanization level by the principal component analysis method,and the relationship between the surface DTR,land use /land cover and urbanization was explored thoroughly.The main conclusions are as follows:(1)From the perspective of interannual variation,the annual average DTR change curve first increased and then decreased,and the trend line generally showed a downward trend and the annual average DTR had a smaller variation.The average DTR anomaly in 2003 and 2016 was less than 0,lower than the average DTR level in the study period,and the average DTR in 2007,2010 and 2013 was higher than the DTR average level in the study period.From the seasonal change,the average DTR and the annual average DTR anomaly in the two seasons of spring and autumn were higher than that in the two seasons of winter and summer,and the variation range was relatively large.(2)From the spatial distribution,the distribution of the average annual DTR smaller values mainly concentrated in the urban area,and the distribution in the urban area reduced during the study period.In 2007,the average DTR smaller values expanded more obviously in the water area,and the area of annual average DTR larger values were mainly distributed in Tongshan and Jiawang District,and the distribution area obviously expanded.In 2003,2010 and 2013,the area was larger where the average annual DTR anomaly was larger than 0,and most of them concentrated.The area was small and scattered where the anomaly was less than 0.(3)The average DTR of the five years' cover types in each area was in the order of forest and grass land > unused land > farmland > construction land > water.The curve of change was similar,and all of them first rose and then decreased.The DTR values were generally higher and the difference was small,except for the DTR in water.(4)The degree of linear correlation between DTR and NDVI in the study area was weak.The correlation coefficient of the three polynomial fitting was 0.5771,the correlation was not high and only moderate.(5)The amount of land use/cover has changed,the decrease of farmland area has reduced,and the construction land has obviously increased since 2010,and the area of water and unused land has reduced slightly.In 2016,compared with 2003,the land of DTR increased included the land transformed into construction land,farmland and unused land,and the land of DTR reduced included the land transformed into forest grassland,water and unchanged land.The correlation coefficient was 0.043 and it was weak when studying the annual average DTR and the mean of comprehensive index of land use degree,but the DTR and the comprehensive index of land use degree were significantly related when studying all grid pixel DTR and the comprehensive index of land use degree in each year.(6)The DTR of each phase has a certain positive and negative correlation with the urbanization index.The comprehensive interpretation rate of the previous two principal components of the urbanization development index of the study area was the best,which was 95.515.The fitting effect of the three regression models between the DTR of each phase and the urbanization development index was the best.