| Since the 21st century,urban ecological problems are becoming more and more serious.Among them,the urban heat island problem are becoming a common problem.Therefore,how to alleviate the urban heat island effect is becoming an urgent problem to be solved by the academic community and the government.In view of this,this article used remote sensing data to analyze the temporal and spatial evolution of urban heat islands and urban land from multiple perspectives over a long time,and analyzed the response mechanism of urban heat islands to urban land cover from a qualitative and quantitative perspective.With the development of economy,the adjustment of industrial structure and the reform of technology,combined with the results of this research,it can not only provide new ideas for alleviating urban heat islands,but also provide reference for urban planning and related personnel.Based on MOD11A2,MOD09A1,MCD12Q1,Globe Land30,and elevation data,by using gravity trajectory analysis,landscape pattern analysis,spatial autocorrelation analysis,bivariate Pearson analysis,regression analysis and other methods for quantification,The temporal and spatial evolution patterns of urban land cover and urban heat island effect and the correlation between them were studied.The main content and conclusions of the study include:(1)The temporal and spatial evolution pattern of urban land cover from 2001 to 2019:The urban land cover landscape were gradually gathered and clustered in 19 years,and the overall shape had also tended to be simple.By 2019,the LPI,PD,LSI,and AI indices of the urban landscape were 47.18%,0.65,6.08,and 67.77%,respectively.Regarding urban construction land,the area increased from 321 km~2 to 434 km~2 in 19 years,an increase of35.20%;in 19 years,the trajectory of the center of gravity was at right angles,and the offset was 687.61 m.For the cultivated land,the area in 2019 was only 135 km~2,and its center of gravity trajectory was human's shape,all falling in the Qingshanhu District,and the total offset of the center of gravity was 3278.94 m.For the green space,the area in 2019 was 250km~2,which was mainly distributed near the newly built area and the Honggutan District,and the total offset of the center of gravity was 2915.38 m.The trajectory of the center of gravity of the water was relatively simple,mainly in the north-south direction,with a total offset of912.84 m.(2)The temporal and spatial evolution pattern of urban heat islands from 2001 to 2019:The aggregation of day and night urban heat island landscapes had decreased in 19 years,and the shape has become more complex.By 2019,the LPI,PD,LSI,and AI indices of daytime heat island landscapes are 8.51%,0.87,7.07,61.64%,respectively.Night landscape index were 48.87%,0.53,5.89,69.57%.For the daytime urban heat island,the area increased from61 km~2 to 150 km~2 in 19 years,with an expansion rate of 145.90%;the nighttime urban heat island increased by 39.34%.During the day,the center of gravity of the heat island area was relatively scattered,in a ring shape,with a total offset of 3005.41 m;the track of the center of gravity of the heat island at night was chaotic and disorderly,with a total offset of 3264.89 m;the day and night heat island landscape had significant spatial autocorrelation.The global Moran's I in 2019 were 0.279 and 0.425 respectively.According to the results of local Moran's I,the area of the high value clustering area of day and night in 2019 were 129 km~2and 146 km~2,respectively.(3)The correlation between urban land use and elevation and urban heat island:The urban land landscape had a very significant correlation with the urban heat island.The intensity of heat island at day and night has a very significant positive correlation with the NDBI and a significant negative correlation with the NDVI.The MNDWI has an opposite correlation with the intensity of the heat island at day and night.The regression analysis results of landscape pattern and surface temperature show that for every 10%increase in LPI and AI index,the surface temperature rises by about 0.39?and 0.93?during the day,and about 0.16?and 0.53?at night.Cultivated land and green land are opposite to construction land.For every 10%increase in LPI and AI index of green land,the surface temperature will drop by about 0.20?and 0.40?respectively;for every 10%increase in LPI and AI index of cultivated land,the surface temperature will drop by about 0.33?and 0.50?respectively during the day.In different periods of day and night,the landscape pattern of the water has an opposite effect on the urban heat island.This paper also analyzed the correlation between DEM and urban heat island.The results of the study showed that the surface temperature of the central urban area of Nanchang generally increases first and then decreases with the increase in elevation. |
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