Abstract:

Study of the influence of urbanization on the climate environment can provide a basis for urban adaptation to climate change. Based on the data of meteorological stations in urban and suburban areas of Xi’an from 1961 to 2022, the impacts of urbanization in different stages on local climate were analyzed by comparison between urban and suburban areas, linear tendency estimation and Mann-Kendall (M-K) test. The results show that the urban heat island (UHI) effect in Xi’an has been significantly enhanced since the 1990s, and it was stronger in winter and spring. The UHI exhibits distinct diurnal and seasonal variations. The relatively stable high-value and low-value periods occur from 21:00 on the same day to 06:00 the next day, and from 11:00 to 16:00, respectively. The maximum value in winter appears 2-3 hours earlier than that in summer, while it ends 2-3 hours later than in summer. The contribution rate of urbanization development to the minimum temperature (T_min) was greater than that to the maximum temperature (T_max). The contribution rate of urbanization development to T_max, T_min and diurnal temperature range (DTR) was the largest in spring, while that to average temperature (T_ave) was the largest in summer. The urban rain island (URI) effect primarily occurs during winter and spring. During the rapid urbanization period (1991-2022), the URI effect intensified, characterized by increased frequency and intensity of moderate-to-heavy precipitation in urban areas, alongside a reduction in light precipitation. The urban turbidity island (UTI) and urban dry island (UDI) effects were more pronounced in both winter and spring. For the entire year, the absolute difference in sunshine duration (SD) between urban and suburban areas during the rapid urbanization period was 0.73 h, and the absolute difference in relative humidity (RH) was 4.38%. The contribution rate of urbanization development to SD and RH was the largest in spring and summer, respectively.

Key words: climate effects of urbanization, contribution rate of urbanization, comparison between urban and suburban areas, meteorological elements, Xi’an

摘要： 研究城市化发展对气候环境的影响，可为城市应对气候变化提供依据。利用1961－2022年西安城区和郊区气象站数据，采用城郊对比、线性倾向估计、M-K检验等，分析城市化发展不同阶段对西安气候环境的影响。结果表明：西安城市热岛效应（Urban Heat Island，UHI）在20世纪90年代后显著增强，且在冬季和春季较强。UHI有明显的日变化和季节变化特征，当日21：00至次日06：00和11：00－16：00为相对稳定的高值和低值时段，冬季最大值出现时间比夏季提前2~3 h，结束时间比夏季滞后2~3 h。城市化发展对最低气温（T_min）的影响贡献率大于最高气温（T_max），对T_max、T_min和气温日较差（Diurnal Temperature Range，DTR）的影响贡献率均在春季最大，对平均气温（T_ave）的影响贡献率在夏季最大。雨岛效应（Urban Rain Island，URI）主要出现在冬季和春季，城市化快速期（1991—2022年）URI增强，城区中雨及以上等级降水增加，强度更强，小雨减少。浑浊岛效应（Urban Turbidity Island，UTI）和干岛效应（Urban Dry Island，UDI）均在冬季和春季较强，就全年而言，城市化快速期城区和郊区日照时数（Sunshine Duration，SD）差值的绝对值为0.73 h，相对湿度（Relative Humidity，RH）差值的绝对值为4.38%。城市化发展对SD和RH的贡献率分别在春季和夏季最大。

关键词: 城市化气候效应, 城市化影响贡献率, 城郊对比, 气象要素, 西安