昆明强降水对城市化和热环境变化的响应研究

doi:10.12006/j.issn.1673-1719.2023.126

摘要/Abstract

摘要：

局部气候变化下的城市化往往对强降水的发生发展产生重大影响，为探究城市化和热环境对昆明强降水的作用，文中利用昆明市1991—2021年湿季（5—10月）城区昆明站与郊区晋宁站的逐时降水数据进行分析，在揭示不同城市化阶段城郊站点之间的强降水差异和变化趋势基础上，结合MODIS地表温度遥感数据，从快速城市化背景的角度，进一步探讨昆明主城区湿季昼夜城市热环境时空分布情况及其与城区强降水指标之间的定量关系。结果表明，近31年来城郊两站点的强降水量和强降水频次均呈现上升趋势。其中，城区强降水量与强降水频次总体增长速率大于郊区，城郊差异较大，城市化对城区强降水量和强降水频次的贡献率分别达到47%以及40%。昆明城区进入21世纪以来总降水量减少，城区强降水量与强降水频次的贡献率不断上升，其线性趋势均在快速城市化阶段表现出更高的显著性。昆明城区强降水主要活跃在19时至次日05时，属于夜间活跃型单峰结构，强降水峰值出现在凌晨04时，“夜雨”特性显著，强降水频次对强降水量具有主要贡献。在1991—2021年期间，白天城郊站点强降水均无明显变化趋势，而夜间城区的强降水量与强降水频次的贡献率趋势上升，并显著表现在近17年快速城市化阶段。快速城市化时期夜间城市热环境指数相比白天显著升高，城市热效应明显。通过相关分析发现，城市热环境对城区强降水具有正向促进作用，而这种作用以高显著性主要表现在夜间。

关键词: 城市热环境, 城市热岛, 城市化, 强降水, 昆明主城区

Abstract:

Urbanization under local climate change often has a significant impact on the occurrence and development of heavy precipitation. In order to explore the role of urbanization and thermal environment on heavy precipitation in Kunming, the hourly precipitation data of Kunming station in the urban area and Jinning station in the suburban area during the wet season (May to October) from 1991 to 2021 were used for analysis. On the basis of revealing the difference and change trend of heavy precipitation at urban and suburban stations in different urbanization stages, combined with MODIS land surface temperature remote sensing image data, further exploration was made on the spatio-temporal distribution of urban thermal environment and its quantitative relationship with urban heavy precipitation in the daytime and nighttime during the wet season in the main urban area of Kunming. The results are as below. In the past 31 years, the heavy precipitation amount (HPA) and heavy precipitation frequency (HPF) at urban and suburban stations have shown an upward trend. Among them, the overall growth rate of HPA and HPF in urban areas is greater than that in suburbs, with significant differences between urban and suburban areas. The contribution rates of urbanization to HPA and HPF in urban areas reach 47% and 40%, respectively. Since the beginning of the 21st century, the total precipitation in Kunming urban area has decreased, and the contribution rate of HPA and HPF in the urban area has been continuously increasing, with their linear trends showing higher significance during the rapid urbanization stage. The heavy precipitation in Kunming urban area is mainly active from 19:00 to 05:00, belonging to a single peak pattern with a nighttime activity. The peak of heavy precipitation occurs at 04:00, and the “night rain” characteristic is significant. HPF has the main contribution to HPA. During the period from 1991 to 2021, there was no significant trend in heavy precipitation at urban and suburban stations during the daytime, while the contribution rate of heavy precipitation and frequency at night at urban station showed an upward trend, which was significant in the rapid urbanization stage of the past 17 years. From 2005 to 2021, the nighttime urban thermal environment index significantly increased compared to the daytime, indicating a significant urban thermal effect. Through correlation analysis, it is found that the urban thermal environment has a positive promoting effect on heavy precipitation in urban areas, and the high significance of this effect is mainly manifested at night.

Key words: Urban thermal environment, Urban heat island, Urbanization, Heavy precipitation, Main urban area of Kunming

吴燕汶, 晏红明, 史正涛, 舒康宁. 昆明强降水对城市化和热环境变化的响应研究[J]. 气候变化研究进展, 2023, 19(6): 723-737.

WU Yan-Wen, YAN Hong-Ming, SHI Zheng-Tao, SHU Kang-Ning. Research on the response of heavy precipitation in Kunming to urbanization and thermal environment changes[J]. Climate Change Research, 2023, 19(6): 723-737.

图/表 15

图1 研究区位置及气象站点分布

Fig. 1 Map of study area and distribution of meteorological stations

表1 地表温度等级划分标准

Table 1 Standard for classification of surface temperature levels

图2 1991—2021年昆明市多年平均总降水频次PF (a)、总降水量PA (b)、强降水频次HPF (c) 和强降水量HPA (d)空间分布

Fig. 2 Spatial distribution of annual total precipitation frequency (PF, a), total precipitation amount (PA, b), heavy precipitation frequency (HPF, c), and heavy precipitation amount (HPA, d) in 1991-2021 in Kunming

图3 1991—2018年昆明主城区不透水面变化时空分布(a)和Pettitt同质性检验(b)

Fig. 3 Change of impervious area in main urban area of Kunming from 1991 to 2018. (a) Spatiotemporal distribution, (b) Pettitt homogeneity

图4 1991—2021年湿季城郊两站强降水量（HPA,a）与强降水频次(HPF,b) 变化趋势

Fig. 4 The change trend of heavy precipitation amount (HPA, a) and heavy precipitation frequency (HPF, b) at urban and suburban station during the wet season from 1991 to 2021

图5 1991—2021年湿季昆明站历年降水的变化情况 (a)总降水量（PA）和强降水量贡献率（HPAC)，(b)总降水频次（PF）和强降水频次贡献率（HPFC）

Fig. 5 Changes of precipitation over the years at Kunming station in wet season from 1991 to 2021. (a) Total precipitation amount (PA) and contribution rate of heavy precipitation amount (HPAC), (b) total precipitation frequency (PF) and contribution rate of heavy precipitation frequency (HPFC)

图6 1991—2021年湿季昆明站强降水日变化 (a)强降水量（HPA）和强降水量贡献率（HPAC），(b)强降水频次（HPF）和强降水频次贡献率（HPFC）

Fig. 6 The daily variation of heavy precipitation at Kunming station in the wet season from 1991 to 2021. (a) Heavy precipitation amount (HPA) and the contribution rate of heavy precipitation amount (HPAC), (b) heavy precipitation frequency (HPF) and the contribution rate of heavy precipitation frequency (HPFC)

图7 昆明站和晋宁站1991—2021年湿季不同城市化阶段强降水频次（HPF）日变化曲线

Fig. 7 Diurnal variations curve of heavy precipitation frequency (HPF) in different urbanization stages of Kunming station and Jinning station during the wet season in 1991-2021

图8 1991—2021年湿季昆明城郊强降水昼夜变化对比

Fig. 8 Comparison of diurnal (a, c) and nighttime (b, d) changes of heavy rainfall in Kunming during the wet season from 1991 to 2021 between urban (c, d) and suburban (a, b) station

图9 昆明站2005—2021年湿季月均气温与LST相关统计

Fig. 9 Correlation statistics of monthly average temperature and LST in wet season from 2005 to 2021 at Kunming station

表2 昆明站（2005—2021年）与呈贡站（2011—2021年）湿季月均气温分别与LST相关统计表

Table 2 Statistical table of monthly average temperature and LST in wet season from 2005 to 2021 at Kunming station and from 2011 to 2021 at Chenggong station

图10 2005—2021年湿季昼夜平均地表温度（LST）变化曲线(a)与城市热岛比例指数（URI）变化曲线(b)

Fig. 10 Average land surface temperature (LST) variation curve (a) and urban-heat-island ratio index (URI) variation curve (b) in day and night during the wet season of 2005-2021

图11 2005—2021年昆明主城区昼夜地表温度等级

Fig. 11 Surface temperature level in day and night in main urban area of Kunming in 2005-2021

图12 昼夜城市热环境与降水指标的相关系数矩阵注：*p≤0.05，**p≤0.01，***p≤0.001；右上三角表示昼，左下三角表示夜；圆圈大小表示相关系数绝对值大小，灰色圆圈表示负相关，空心圆圈表示正相关。

Fig. 12 Correlation coefficient matrix between urban thermal environment and precipitation indicators in day and night

图13 1991—2021年湿季昆明主城区夜间K指数年际变化

Fig. 13 Inter-annual variation of K index in the main urban area of Kunming during the wet season from 1991 to 2021

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