| With the global warming of the climate,extreme weather occurs frequently,and the disastrous weather causes huge losses to the lives and property of the people.The current climate change is closely related to human activities,and urbanization is one of the most prominent manifestations of human activities.The local climatic effects caused by urbanization have led to abnormal changes in the local climate,and the climatic effects of the city's "heat island,rain island and dry island" have emerged.Due to human activities,climate change in urban belts is more complex and variable.On the one hand,it is affected by global climate change,that is,the impact of climate system changes,and on the other hand,local climate change caused by human activities and over-exploitation.The impact of climate change brought about by urbanization.How to separate the urban belt(circle)climate change brought by urbanization is a technology of concern at home and abroad.The suburbs or villages on the edge of the urban circle are far from the urban area and have little influence on the local climate change brought by urbanization.A comparison station for urbanized climate effects.Taking Hefei City Circle centered on Hefei City as an example,this paper uses urban population data,socio-economic data and night lighting data to select typical urban sites and suburban sites that are compared with them,using suburban contrast method("UMR method").Quantitatively calculate the urbanization impact and urbanization contribution rate of each factor by screening and homogenizing the daily temperature,precipitation,relative humidity and other data from 1980 to 2017,and analyze the differences in urban and rural factors.The spatial distribution of the trend of each factor is analyzed.Taking Hefei as an example,the principal component analysis is used to obtain the urbanization comprehensive index,and regression modeling is carried out with each meteorological element to reveal the relationship between urbanization and regional climate change.The following conclusions were obtained:(1)The influence of urbanization on the temporal distribution of temperatureIn the development process of Hefei City Circle,the impact of urbanization on temperature is mainly reflected in the fact that urbanization has a significant increase in the annual average temperature and annual average maximum temperature of urban stations in Hefei City Circle.The suburbs have a reduced impact.The urbanization rate of the annual average temperature,the annual minimum temperature and the annual maximum temperature is 0.12?/10a,-0.05?/10a,and by the urban and suburban contrast method(UMR).0.24 ?/10 a,the temperature contribution rate was 21%,-11%and 39%.The urbanization of Hefei City Circle has the following effects on the temperature of the four seasons of the city station:except for the autumn,urbanization has increased the average temperature;the average temperature of the four seasons in the Hefei city circle has shown an increasing trend.The average minimum temperature is increasing in autumn and winter,and decreasing in spring and summer.When the temperature of the Hefei city circle is detected as a mutation,the annual average temperature change mainly occurs during the slow period of urban development(1980-2000).The specific annual average temperature is 1985;the annual minimum and annual maximum temperature are both Occurred in the rapid development of urban development(2001-2017),the specific annual minimum temperature of the sudden change in the year of 2013 and the annual average maximum temperature of the sudden change point is from 2010.(2)Influence of urbanization on the temporal distribution of precipitation and relative humidityThe impact of urbanization on total precipitation is mainly reflected in the fact that during the slow development period of urban development(1980-2000),the annual precipitation shows a downward trend,and the urban development period(2001-2017)shows a clear upward trend.The urban-suburban contrast(UMR)sequence of annual precipitation also showed less obvious growth,but it increased significantly after 2010.The precipitation in the four seasons is characterized by an increase in summer and autumn,and a decrease in spring and winter.The impact of urbanization on the number of precipitation days is mainly as follows:the number of days of precipitation is significantly reduced,and the number of days of precipitation in the four seasons is slightly increased except for the number of days of precipitation in winter.,its three seasons are significantly reduced.The cyclical changes of annual and seasonal precipitation in Hefei City Circle mainly exist in the scale cycles of quasi-2-4a,4-8a and 8-16a.The cyclical variation of annual precipitation is mainly dominated by periodic oscillations of small scales of 2?4a.The cyclical variation of precipitation in the four seasons is as follows:the spring precipitation is the same as the annual precipitation variation,and the small-scale oscillation is more significant in the quasi-2-4a;the precipitation oscillations in the summer and winter are mainly the most significant in the quasi-2a period,and the fluctuation Relatively frequent.In the fall,the shock is more pronounced in the quasi-8a period.The influence of urbanization on relative humidity is mainly:the urbanization of Hefei city circle has obvious influence on the relative humidity of urban stations.The relative humidity and suburban contrast(UMR)sequences of the four seasons show a downward trend,and autumn and winter are more obvious.The "dry island effect" of the city is remarkable.(3)The influence of urbanization on the spatial distribution of temperatureThe influence of urbanization on the spatial distribution of temperature is mainly reflected in the large temperature increase rate of urban stations in the central area of the urban circle,and the contribution rate of urbanization is also relatively high.With the continuous advancement of urbanization,the urban stations in the central part of the urban circle The annual average temperature and the annual maximum temperature increase are also increasing;compared with urban stations,the growth rate of suburban stations is relatively slow.(4)Influence of urbanization on the spatial distribution of precipitationThe influence of urbanization on the spatial distribution of precipitation is more significant than the temperature.The spatial distribution of standardized relative precipitation in the year and the four seasons changed significantly in 1980-2000 and 2001-2017.The spatial distribution of relative precipitation in the year and autumn was generally consistent.As the urban process continued to advance,the site with relatively more precipitation was The center of the city circle is concentrated;in spring and autumn,it is concentrated in the southeast of the city circle;in summer,it is not very obvious.(5)Influence of urbanization on the spatial distribution of annual average relative humidityDuring the different periods of urbanization in Hefei City Circle,the spatial distribution of annual average relative humidity changed significantly.During the slow development period of urban development(1980-2000),the annual relative humidity high value area was located in the southeast direction of the urban circle;the rapid development of urban development(2001-2017)Year),the relative humidity high value area is located in the northwest direction of the city circle.(6)Analysis of curve estimation models of Hefei urban development in different periods and regional meteorological elementsUsing the principal component analysis method,calculate the Hefei urban development comprehensive index,and establish a city development comprehensive index and annual average temperature,annual average maximum temperature and annual average minimum temperature,annual precipitation days,annual precipitation and annual relative humidity curve estimation.model.The rapid development of urban development has a relatively slower fitting period,and the best fitting effect with annual relative humidity is the second,the temperature is second,and the precipitation is the worst. |
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