珠三角城市化对气温时空差异性影响

利用1967-2015年珠江三角洲21个气象站逐日气温资料,根据人口数量、人口密度和夜间灯光数据等数据集划分城市和郊区站点类型,在此基础上,对比不同时空尺度城市站和郊区站气温变化,分析了城市化对气温影响的时空差异性。结果表明：① 1967-2015年,珠三角地区年平均气温、平均最高气温和最低气温均显著升高,平均最低气温的增温速率最高,分别是平均气温的1.05~1.16倍和平均最高气温的0.95~1.32倍。其中,年平均气温变化速率的季节差异普遍表现为秋冬季节增温最强,增温速率均高于0.3 ℃/10a,春夏季节增温较弱,增温速率最低为0.16 ℃/10a。② 利用城市和海表温度对比研究城市化效应,受城市化影响,珠三角年平均气温的增温趋势是0.096 ℃/10a。③ 利用城市和郊区对比研究城市化效应,1967-2015年城市化对城区的气温升高具有显著贡献,而且城市化对平均最高气温及最低气温增温的贡献率最大。其中,城市化对年平均气温变化的贡献率的季节差异表现为夏冬季节较强,贡献率高于11.8%,春秋季节较弱,贡献率最低仅为4.46%。④ 站点划分方法,城市化发展不同阶段及研究时间尺度的选择均导致城市化增温效应的研究结果具有较大不确定性。不同站点分类方法多指示城市化对最低气温升高的贡献率最强,最高可达到38.6%。

Impacts of urbanization on spatio-temporal variations of temperature over the Pearl River Delta

Daily temperature data at 21 stations across the Pearl River Delta during the period of 1967-2015 were selected, and these stations were divided into urban stations and suburban stations based on population, population density and DMSP/OLS data. Meanwhile, spatio-temporal variations due to urbanization were investigated by comparing the temperature changes at urban and suburban stations. The results show that: (1) In the past 50 years, the annual average temperature, the average maximum temperature and the average minimum temperature in the Pearl River Delta region increased significantly, and the average minimum temperature increased at the highest rate, or 1.05-1.16 times of the average temperature and 0.95-1.32 times of the average maximum temperature, respectively. Among them, the seasonal difference of annual average temperature change rate is generally manifested as the strongest temperature increase in autumn and winter, with the temperature increase rate higher than 0.3 ℃/10a, and the temperature increase rate is weaker in spring and summer, with the temperature increase rate as low as 0.16 ℃/10a. (2) Using urban and Sea Surface Temperature (SST) comparison to study the urbanization effect, affected by urbanization, the annual average temperature of the Pearl River Delta is increasing by 0.096 ℃/10a. (3) Using urban and rural comparison to study the urbanization effect, from 1967 to 2015, urbanization leads to the temperature increase in urban areas. Generally speaking, urbanization contributes the most to the increase of average minimum temperature. Meanwhile, the seasonal difference in the contribution rate of urbanization to the annual average temperature change indicates that the increase rate is stronger in summer and winter, with the contribution rate higher than 11.8%, and lower in spring and autumn, with the contribution rate being only 4.46%. (3) The selection of stations division method, the different periods of urbanization development and time scale of research all lead to the uncertainty of the research results on the warming effect of urbanization. Different stations classification methods indicate that urbanization contributes the most to the increase of the minimum temperature, and for a longer time scale, the contribution rate of urbanization to the increase of the minimum temperature is up to 38.6%.