Urban Expansion and Drying Climate in an Urban Agglomeration of East China

Luo, Ming; Lau, Ngar‐Cheung

doi:10.1029/2019gl082736

Cited by 114 publications

(105 citation statements)

References 73 publications

(127 reference statements)

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“…vapour pressure and specific humidity) at any given point in time. Similar findings have been observed in regard to spatial variation in temperature (Cavan et al 2014;Feyisa et al 2014), humidity (Adebayo 1991;Yang et al 2017;Hao et al 2018;Luo and Lau 2019) and heat index (Hass et al 2016;Scott et al 2017). Materials such as concrete and asphalt and the presence of buildings promote the transformation of shortwave radiation into heat and its retention (Landsberg 1981;Oke 1987).…”

Section: Discussionsupporting

confidence: 78%

Spatiotemporal dynamics of urban climate during the wet-dry season transition in a tropical African city

2021

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The Urban Heat Island effect has been the focus of several studies concerned with the effects of urbanisation on human and ecosystem health. Humidity, however, remains much less studied, although it is useful for characterising human thermal comfort, the Urban Dryness Island effect and vegetation development. Furthermore, variability in microscale climate due to differences in land cover is increasingly crucial for understanding urbanisation effects on the health and wellbeing of living organisms. We used regression analysis to investigate the spatial and temporal dynamics of temperature, humidity and heat index in the tropical African city of Kampala, Uganda. We gathered data during the wet to dry season transition from 22 locations that represent the wide range of urban morphological differences in Kampala. Our analysis showed that the advancement of the dry season increased variability of climate in Kampala and that the most built-up locations experienced the most profound seasonal changes in climate. This work stresses the need to account for water availability and humidity to improve our understanding of human and ecosystem health in cities.

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Section: Discussionsupporting

confidence: 78%

Spatiotemporal dynamics of urban climate during the wet-dry season transition in a tropical African city

2021

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“…The RH under heat waves were lower than that under normal conditions for most hours in all three cities. This phenomenon is also called the urban dry island, which can be intensified by urban expansion as well (Hao et al, ; Luo & Lau, ; Yang, Ren, et al, ). The RH in Shanghai was higher than that in Beijing and Guangzhou, which could explain the highest AT in Shanghai.…”

Section: Resultsmentioning

confidence: 99%

Amplified Urban Heat Islands during Heat Wave Periods

et al. 2019

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Heat waves and urban heat islands (UHIs) may interact together, but the dependence of their interaction on background climate is unclear. Hourly meteorological observations in June to August from 2013 to 2015 collected in the megacities of Beijing (temperate semihumid monsoon climate), Shanghai (subtropical humid monsoon climate), and Guangzhou (marine subtropical monsoon climate) in China were used to study the interaction. At each megacity, eight rural stations and eight urban stations, respectively, were selected to study the UHI. Although under different background climates, UHIs in Beijing and Guangzhou shared a similar diurnal variability, that is, higher in the nighttime. However, the diurnal cycle is opposite for Shanghai if rural coastal stations were selected as rural reference stations. During heat wave periods, daytime (10:00–16:00) UHIs were intensified by 0.9 ± 0.13 (mean ± 1 standard deviation) °C in Shanghai, nighttime (22:00–4:00) UHIs were intensified by 0.9 ± 0.36 and 0.8 ± 0.20 °C in Beijing and Guangzhou, respectively. The surface solar radiation during the heat wave period was approximately 1.5 times to that under normal conditions in each city. The enhanced solar radiation during heat waves, which was absorbed by the urban canopy in the daytime and released at night, was closely related to nighttime UHIs in Beijing and Guangzhou and daytime UHIs in Shanghai. Additionally, changes in wind direction were observed in Shanghai under heat waves, that is, with more than 63% (wind direction) of the wind originating from neighboring hot cities in the southwest instead of the cool sea breeze from the southeast, which led to a significant increase in daytime UHIs during heat wave periods.

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“…Our result was consistent with Chen et al (2019) and Wang et al (2020) who concluded that the cropland greening in China and the Loess Plateau was mainly caused by human land‐use management practices such as multiple cropping and heavy fertilizer usage. Urbanization and urban expansion, on the one hand, generally occurred at the expense of grassland or cropland, which directly related to the decrease in vegetation covers and ET of the land surface, thereby reducing atmospheric humidity and elevating vapor pressure deficit in urban core areas (Hao et al, 2018; Lin et al, 2020; Luo & Lau, 2019). However, the growth of urban areas only accounted for a small fraction of land changes in the Loess Plateau.…”

Section: Discussionmentioning

confidence: 99%

Rapid Urbanization and Agricultural Intensification Increase Regional Evaporative Water Consumption of the Loess Plateau

Liang

Zhang²,

Jing-bo

et al. 2020

JGR Atmospheres

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Changing evapotranspiration (ET) will impact freshwater availability, knowledge of which is a critical prerequisite for policy development related to water resources management in an evolving climate, especially for water-limited regions. However, the socioeconomic effects are not considered due to the lack of detailed information about this. Here we used a well-validated remote sensing model and multiple socioeconomic factors to investigate the driving factors of ET changes over the Loess Plateau during 1982-2012. Results showed that the modeled annual ET significantly increased by~2 mm yr −2 during this period (p < 0.001), caused by increased transpiration (2.16 mm yr −2) and interception (0.27 mm yr −2), which was partly offset by decreased soil evaporation (−0.47 mm yr −2). Meanwhile, although the average ET of the forest was larger (480.4 ± 14.8 mm yr −1), it was found that the change in total ET of the region was dominated by that in grassland and cropland (1.1 km 3 yr −2 , 90% altogether). Factorial simulations indicated that the intensifying ET over 79.4% and 9.1% of the study area can be explained by vegetation greening and climate change, respectively. Further analysis suggested that the vegetation greening and the increased ET were primarily associated with the rapid urbanization and agricultural intensification. Our findings highlight the potential unfavorable effects of socioeconomic activities on water resources management on this coupled natural-human system that is already facing water scarcity issues. 1. Introduction Water is especially valuable for food production and ecosystem functioning (Immerzeel et al., 2020; Oki & Kanae, 2006). Global trends of population growth, rising living standards, and rapidly increasing urbanization are increasing the demand for water resources (Florke et al., 2013; Steffen et al., 2015; Wada et al., 2014). Added to this is the growing threat of climate change which will have enormous effects on water availability, and thus challenge global sustainable development (Qin et al., 2020). It has been reported that water scarcity affects more than 40% of the global population and is projected to rise. Over 1.7 billion people are currently living in river basins where water use exceeds recharge (https://www.un.org/sustainabledevelopment/ water-and-sanitation/). The contradiction between the supply and demand of water resources is particularly strong in arid and semi-arid regions where these competing uses can be found upstream, downstream, and sometimes across borders (

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Urban Expansion and Drying Climate in an Urban Agglomeration of East China

Cited by 114 publications

References 73 publications

Spatiotemporal dynamics of urban climate during the wet-dry season transition in a tropical African city

Spatiotemporal dynamics of urban climate during the wet-dry season transition in a tropical African city

Amplified Urban Heat Islands during Heat Wave Periods

Rapid Urbanization and Agricultural Intensification Increase Regional Evaporative Water Consumption of the Loess Plateau

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