Study On Urban Temperature Changes At Different Urbanization Levels

Until now,more than half of the world’s population lives in urban areas.Urbanization has brought about agglomeration of the population,changes in the underlying surface,and an increase in human heat.The resulting increase in urban temperatures has had a very negative impact on the lives of urban residents and the sustainable development of cities.It has been highly valued by all countries in the world and has become one of the hot topics studied by scholars at home and abroad.In this study,Fuzhou City and Zhangzhou City(Fujian Province)were used as the main research areas.Using multiple temperature data,the characteristics of the temperature changes in the two cities for many years and the effects of different degrees of urbanization on the urban air temperature changes were discussed.Based on this,for the stable development of cities,the key factors affecting the degree of urbanization were selected,and the impact of urban air temperature on cities with different degrees of urbanization was further analyzed.The main conclusions are as follows:(1)The average annual temperature,the annual maximum temperature,and the average annual minimum temperature of Zhangzhou and Fuzhou all increased during the period from 1961 to 2013,and began to increase significantly in the 1990s.The average annual minimum temperature rise in Zhangzhou is relatively large,and the average annual maximum temperature rise is small.The temperature change trend in Fuzhou is the same as that in Zhangzhou,but the increase is smaller than that in Zhangzhou.For the four seasons,the average temperature and the average minimum temperature both rose rapidly in autumn and winter,and the average maximum temperature rose rapidly in spring and summer.Except for summer,the seasonal temperature changes in Zhangzhou are greater than Fuzhou,especially in winter.(2)From 1961 to 2013,the urbanization effects of annual average temperature,annual maximum temperature,and average annual minimum temperature in Fuzhou were 0.014℃/10a,-0.191℃/10a,and 0.118℃/10a respectively,and the contribution rate of urbanization was 5.93%,-77.3%,and 43.5%respectively.The urbanization impacts of annual average temperature,annual maximum temperature,and average annual minimum temperature in Zhangzhou were 0.09℃/10a 0.018℃/10a,and 0.041℃/10a respectively,and the contribution rate of urbanization was 30.6%,6.98%,and 12.3%respectively.In Zhangzhou,the average temperature has risen due to urbanization;In Fuzhou,the minimum temperature has risen due to urbanization.For the highest temperature,the impact of urbanization has increased in the Zhangzhou area and cooling has occurred in the Fuzhou area.(3)The variation trend of OBS temperature anonalies and R1 temperature anomalies are consistent,but the warming trend of R1 temperature anomaly is not as good as that of OBS.The linear trend of the annual mean temperature OMR in Fuzhou and Zhangzhou was 0.125℃/10a and 0.149℃/10a,respectively.And the contribution rate of OMR warming was 53.2%and 50.7%,respectively.The rise in urban temperatures in Zhangzhou and Fuzhou is more than half due to the impact of urbanization or land-use change.(4)From 2003 to 2013,the site temperature anomaly,MODIS ground temperature anomaly and reanalysis data ground temperature anomaly tended to decrease year by year.Among them,the ground surface temperature of MODIS fluctuates is the most.After a certain degree of urbanization,urban temperatures will stop rising and begin to show a downward trend.The four major urbanization indicators only had significant correlation with the temperature at the Fuzhou site and the surface night temperature in Fuzhou.NDVI only has a significant correlation with the air temperature in Zhangzhou.AOD has little to do with the temperature of the two cities.(5)The temperature difference between Fuzhou and Mountain Stations,the temperature difference between Zhangzhou and Mountain Stations(average temperature,highest temperature,and lowest temperature)showed a downward trend.The rate of change in the temperature difference in Fuzhou is significantly greater than that in Zhangzhou,which is most likely due to the effect of aerosol cooling on the temperature.