Analysis Of Temperature Change Trend And Its Urbanization And Sea-atmosphere Impact Factors

According to the temperature indices,China can be divided into ten climatic zones,including the northern temperate zone,the middle temperate zone,the southern temperate zone,the northern subtropical zone,the middle subtropical zone,the southern subtropical zone,the northern tropical zone,the middle tropical zone,the southern tropical zone,and the plateau climatic zone.In order to analyze the characteristics of temperature variations in each climatic zone,using the monthly temperature data of 571 meteorological stations in China from January 1961 to February 2019,the climatic zone type of each station are determined according to the location of each station,and nine climatic zones except the southern tropical zone are finalized.The average temperature,average minimum temperature and average maximum temperature of annual and seasonal change trend of nine climate zones were studied by using the linear trend estimation.The type of meteorological stations is determined by comparing the night light images with statistical data.Specifically,the monthly NPP/VIIRS night light images in 2017 are synthesized into the annual image,which is combined with the latest statistics of built-up area in each province in 2017 released by the Ministry of Housing and Urban-rural Development,to determine the urban threshold of each province.The urban threshold is as the standard,which compares the maximum average light intensity within 10 km around the meteorological stations.If the maximum average light intensity of a station reaches the urban threshold,the station is an urban station,otherwise,the station is a rural station.Select the rural stations within 200 km around the urban station as the center,and determine the urbanization impact and the urbanization impact contribution rate of each climatic zone by urban minus rural.Analyze the correlation coefficients between each climatic zone temperature and the circulation indices and climate indices,determine the circulation indices and climate indices that are best related to each season temperature in each climate zone,to study the effects of circulation indices and climate indices on temperature changes in each climatic zone.The main conclusions are as follows:(1)The annual and seasonal temperature of most stations over China shows an increasing trend,and the average minimum temperature warming trend is the strongest and the average maximum temperature warming trend is the weakest.The trends of inter-annual,spring,and winter average temperature change show an inverse “?” pattern,the trends of summer and autumn average temperature and annual and four seasons average minimum temperature change show an “ N ” pattern,and the trends of annual and four seasons average maximum temperature show an inverse “ N ” pattern with decreasing characteristics from north to south in space.In general,the warming trend in summer is the weakest,and in winter is the strongest over China.The warming trend of the average temperature and the average maximum temperature in the middle subtropics and the northern climatic zones and the average minimum temperature in the north subtropics and the temperate zones is stronger in spring than in autumn.(2)The urbanization impact of temperature generally shows the warming effect,but the warming effect is not reflected in the middle subtropical zone and the northern tropical zone.The stations with strong warming effects are mainly distributed in the temperate zone and the subtropical coastal areas,and the stations with no warming effect are mainly concentrated in the west of middle subtropical zone.There are more stations with no warming effect in the urbanization impact of the average maximum temperature.On the whole,the urbanization impact and the contribution rate of the average minimum temperature are greater than those of the average maximum temperature.However,the contribution rate of the urbanization impact of the average maximum temperature in some regions has increased significantly,which is relevant to the weaker trend of the summer average maximum temperature.The warming effect of urbanization impact of the average minimum temperature is stronger than that of the average maximum temperature in the middle temperate zone,the south temperate zone,the middle subtropical zone,the south subtropical zone and the plateau climatic zone,while that in the north subtropical zone and the north tropical zone is the opposite.The contribution rate comparisons of the average minimum temperature and the average maximum temperature also exhibit the same characteristics.(3)Each season is significantly related to the current or previous circulation indices and climate indices in each climatic zone.The polar vorticity indices account for the largest proportion in the circulation indices with the best correlation with temperature,and the Atlantic SST indices account for the largest proportion in the climate indices with the best correlation with temperature.Circulation anomalies can directly cause temperature anomalies;SST anomalies can cause circulation anomalies through sea-atmosphere interactions and then cause circulation anomalies in East Asia through atmospheric wave train conduction,and oscillation and teleconnection anomalies can also directly or indirectly cause circulation anomalies in East Asia through atmospheric wave train conduction,which results in temperature anomalies in China.Both circulation indices and climate indices show the trends that cause warming,and most of the indices have significant changes,which can provide relevant explanations for climate warming in each climatic zone.