Amplification Effect of Urbanization on Atmospheric Aridity Over China Under Past Global Warming

Abstract

While it is well known that rapid urbanization poses prominent effects on regional or local temperature changes under global warming, possible impacts of urbanization on the changes in atmospheric aridity (measured by vapor pressure deficit [VPD]) are poorly understood. In this study, we provide a national investigation of the spatiotemporal changes of atmospheric aridity over China in recent decades by analyzing observations at over 2,000 weather stations across China during 1971–2017 and further quantify the effects of urbanization on the atmospheric aridity changes in different subregions. The results show that most parts of China have experienced a significant intensification of atmospheric aridity since the 1970s. Especially, stronger drying trends tend to appear in urban agglomerations with higher urbanization levels and denser population, such as Beijing‐Tianjin‐Hebei (BTH), the Yangtze River Delta (YRD), the Pearl River Delta (PRD), and the Sichuan Basin. It is estimated that urbanization contributed to more than 30% of the total increases in atmospheric aridity in urban core areas (i.e., 32.58%, 27.73%, 30.29%, 42.03%, and 37.33%, respectively, for annual, spring, summer, autumn, and winter VPD). Spatially, urbanization exerted significant amplification effects on increasing VPD in most parts of China (nearly 80% grid cells) except for few areas with higher elevation and complex topography (e.g., Qinghai‐Tibet Plateau and Xinjiang). In particular, the areas with higher urbanization (e.g., BTH, YRD, and PRD) underwent even stronger urbanization effects on amplifying atmospheric aridity. Our findings suggest that how to alleviate atmospheric aridity in future urban planning is worthy of consideration.

Urbanization Amplified Asymmetrical Changes of Rainfall and Exacerbated Drought: Analysis Over Five Urban Agglomerations in the Yangtze River Basin, China

“…(2015) also confirmed that about 80% stations in China experienced prominent increases for dry days (precipitation amount = 0) and decreases for trace days (0 < precipitation amount <0.1 mm/day). Such shift of precipitation from light to intense rainfall accompanied with the enhancement by the urbanization process may further give rise to the aggravation of drought events, which was consistent with the trend of light rainfall and drought shown in Figures 6a and 6b and 6e–6h (Wang et al., 2022a, 2022b, 2022c).…”

“…For example, different from the other urban agglomerations, the heavy rainfall in both rural and urban regions of CY indicated a downward trend from 1981 to 2020. Previous studies confirmed that Western Pacific Subtropical High (WPSH), EAM, and South Asian Monsoon (SAM) exerted substantial effects on the heavy rainfall patterns of the eastern, central, and western Sichuan Basin, respectively (Hu et al., 2009; T. Gao et al., 2019; Wang et al., 2022a, 2022b, 2022c). Besides, due to the unique topography, locations, and complex interaction of diverse climate factors, urbanization showed less effects on the aggravation of drought in urban areas in GZ.…”

“…Meanwhile, under climate change and global warming, urban regions also face disproportionately increasing risk of meteorological and hydrological hazards such as heat stress and floods (L. Chen et al., 2019; Gonzalez & Niyogi, 2021; S. Huang et al., 2021; S. Huang, Zhang, Chen, Ma, Fu, et al., 2022; S. Huang, Zhang, Chen, Ma, Zeng, et al., 2022; S. Huang et al., 2022; X. Huang et al., 2022; X. Zhang et al., 2019). As a result, extensive efforts have been underway toward a more in‐depth and comprehensive understanding of urbanization effects on the local water cycle and climate (Chao et al., 2020; Debbage & Shepherd, 2018; Kishtawal et al., 2011; Nguyen et al., 2022; P. Wang et al., 2022; S. Wang et al., 2022; X. Wang et al., 2022). One focus has been on quantifying the urban‐induced changes in precipitation concerning its intensity, frequency, and spatio‐temporal patterns (Doan et al., 2021; Gu et al., 2019; S. Huang, Zhang, Chen, Ma, Fu, et al., 2022; S. Huang, Zhang, Chen, Ma, Zeng, et al., 2022; S. Huang et al., 2022; J. Liu & Niyogi, 2019; Luo & Lau, 2021; Niyogi et al., 2011; Wang et al., 2021; Yu et al., 2022).…”

“…It is projected that the urban areas would double in 2050 (D. Chen et al., 2021). The notable urban expansion has been accompanied by prominent changes in local precipitation patterns and aggravation of drought (Chen et al., 2019; Wang et al., 2022a, 2022b, 2022c). Therefore, the major objective of this study is to quantify the urbanization effects and contributions to the asymmetrical shift of rainfall and the development of drought events in YRB.…”

Effects of urbanization on multiple human perceived temperatures in South China

“…Note that wind speed can accelerate the airflow around the human body, speeding up the heat exchange between the human body surface and the air to play a cooling effect (Edwards et al, 2015;Roshan et al, 2020), so the wind speed in urban areas is reduced due to the impact of urbanization, which in turn leads to a higher local body temperature than the surrounding areas. The urbanization contribution to other HPT indicators without considering the effect of wind speed is generally smaller than that on air temperature, which may be related to the urban Frontiers in Environmental Science frontiersin.org dry island (UDI) effect due to urbanization, which may reduce the atmospheric humidity and thus offsetting the HPT increases to some extent (Hao et al, 2018;Luo and Lau, 2019;Huang et al, 2022;Wang et al, 2022). Table 2 summarizes the mean urban trend (T u ), rural trend (T r ), urbanization effect (UE), and urbanization contribution (UC) of the HPT under different seasons by averaging all HPT indicators.…”