scholarly journals A Numeric Study of Regional Climate Change Induced by Urban Expansion in the Pearl River Delta, China

2014 ◽  
Vol 53 (2) ◽  
pp. 346-362 ◽  
Author(s):  
Xuemei Wang ◽  
Jingbiao Liao ◽  
Jian Zhang ◽  
Chong Shen ◽  
Weihua Chen ◽  
...  
Keyword(s):  
Wind Speed ◽  
Pearl River Delta ◽  
Urban Expansion ◽  
Regional Climate ◽  
River Delta ◽  
Pearl River ◽  
Rapid Urbanization ◽  
Near Surface ◽  
The Pearl River Delta ◽  
The Pearl River

AbstractThe Pearl River Delta region has experienced rapid urbanization and economic development during the past 20 years. To investigate the impacts of urbanization on regional climate, the Advanced Research core of the Weather Research and Forecasting (ARW-WRF) model is used to conduct a pair of 1-yr simulations with two different representations of urbanization. Results show that the reduction in vegetated and irrigated cropland due to urban expansion significantly modifies the near-surface temperature, humidity, wind speed, and regional precipitation, which are obtained based on the significance t test of the differences between two simulations with different urbanization representations at the 95% level. Urbanization causes the mean 2-m temperature over urbanized areas to increase in all seasons (from spring to winter: 1.7° ± 0.7°C, 1.4° ± 0.3°C, 1.3° ± 0.3°, and 0.9° ± 0.4°C, respectively) and the urban diurnal temperature range decreases in three seasons and increases in one (from spring to winter: −0.5° ± 0.3°C, +0.6° ± 0.3°C, −0.4° ± 0.2°C, and −0.8° ± 0.2°C, respectively). Urbanization reduces near-surface water vapor (1.5 g kg−1 in summer and 0.4 g kg−1 in winter), 10-m wind speed (37% independent of season), and annual total precipitation days (approximately 6–14 days). However, the total rainfall amount increases by approximately 30%, since the decrease in the number of days with light rain (8–12) is overcome by the increase in the number of days of heavy or extreme rain (3–6), suggesting that urbanization induces more heavy rain events over the urban areas. Overall, the effect of urbanization on regional climate in the Pearl River Delta is found to be significant and must be considered in any broader regional climate assessment.

scholarly journals Impacts of aerosols on weather and regional climate over the Pearl River Delta megacity area in China

2011 ◽  
Vol 11 (8) ◽  
pp. 23275-23316 ◽  
Author(s):  
Y. Wang ◽  
Q. Wan ◽  
W. Meng ◽  
F. Liao ◽  
H. Tan ◽  
...  
Keyword(s):  
Pearl River Delta ◽  
Regional Climate ◽  
Wrf Model ◽  
Mesoscale Convective System ◽  
Heavy Precipitation ◽  
River Delta ◽  
Pearl River ◽  
Convective System ◽  
The Pearl River Delta ◽  
The Pearl River

Abstract. Seven-year measurements of precipitation, lightning flashes, and visibility from 2000 to 2006 have been analyzed in the Pearl River Delta (PRD) region, China, with a focus on the Guangzhou megacity area. Statistical analysis shows that the occurrence of heavy rainfall (>25 mm per day) and frequency of lightning strikes are reversely correlated to visibility during this period. To elucidate the effects of aerosols on cloud processes, precipitation, and lightning activity, a cloud resolving – Weather Research and Forecasting (CR-WRF) model with a two-moment bulk microphysical scheme is employed to simulate a mesoscale convective system occurring on 28 Match 2009 in the Guangzhou megacity area. The model predicted evolutions of composite radar reflectivity and accumulated precipitation are in agreement with measurements from S-band weather radars and automatic gauge stations. The calculated lightning potential index (LPI) exhibits temporal and spatial consistence with lightning flashes recorded by a local lightning detection network. Sensitivity experiments have been performed to reflect aerosol conditions representative of polluted and clean cases. The simulations suggest that precipitation and LPI are enhanced by about 16 % and 50 %, respectively, under the polluted aerosol condition. Our results suggest that elevated aerosol loading suppresses light and moderate precipitation (less than 25 mm per day), but enhances heavy precipitation. The responses of hydrometeors and latent heat release to different aerosol loadings reveal the physical mechanism for the precipitation and lightning enhancement in the Guangzhou megacity area, showing more efficient mixed phase processes and intensified convection under the polluted aerosol condition.

scholarly journals Projected Urbanization Impacts on Surface Climate and Energy Budgets in the Pearl River Delta of China

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Chunhong Zhao ◽  
Qunou Jiang ◽  
Zhongxiao Sun ◽  
Haiyue Zhong ◽  
Shasha Lu
Keyword(s):  
Land Use ◽  
Air Temperature ◽  
Pearl River Delta ◽  
Surface Air Temperature ◽  
Climate Impacts ◽  
River Delta ◽  
Pearl River ◽  
Near Surface ◽  
The Pearl River Delta ◽  
The Pearl River

The climate impacts of future urbanization in the Pearl River Delta (PRD) region in China were simulated with the Dynamics of Land Systems (DLS) model and the Weather Research and Forecasting (WRF) model in this study. The land use and land cover data in 2000 and 2020 were simulated with the DLS model based on the regional development planning. Then the spatial and temporal changes of surface air temperature, ground heat flux, and regional precipitation in 2020 were quantified and analyzed through comparing simulation results by WRF. Results show that the built-up land will become the dominant land use type in the PRD in 2020. Besides, the near-surface air temperature shows an increasing trend on the whole region in both summer and winter, but with some seasonal variation. The urban temperature rise is more apparent in summer than it is in winter. In addition, there is some difference between the spatial pattern of precipitation in summer and winter in 2020; the spatial variation of precipitation is a bit greater in summer than it is in winter. Results can provide significant reference for the land use management to alleviate the climate change.

scholarly journals Spatio-temporal dynamics of flood exposure in Shenzhen from present to future

2021 ◽  
pp. 239980832199154
Author(s):  
Gizem Mestav Sarica ◽  
Tinger Zhu ◽  
Wei Jian ◽  
Edmond Yat-Man Lo ◽  
Tso-Chien Pan
Keyword(s):  
Pearl River Delta ◽  
Temporal Dynamics ◽  
Flood Hazard ◽  
River Delta ◽  
Pearl River ◽  
Rapid Urbanization ◽  
The Pearl River Delta ◽  
Flood Exposure ◽  
Spatio Temporal ◽  
The Pearl River

The Pearl River Delta metropolitan region is one of the most densely urbanized megapolises worldwide with high exposure to weather-related disasters such as storms, storm surges and river floods. Shenzhen megacity has been the fastest growing city in the Pearl River Delta region with a significant increase of resident population from 0.32 million in 1980 to 13.03 million in 2018. Being a flood-prone city, Shenzhen’s rapid urbanization has further exacerbated potential flood losses and forthcoming risk. Thus, evaluating the changes in its exposure from present to future is essential for flood risk assessment, mitigation and management purposes. The main objective of this study is to present a methodology to assess the spatio-temporal dynamics of flood exposure from present to future using high-resolution and open-source data with a particular focus on the built-up area. To achieve this, the SLEUTH model, a cellular automata-based urban growth model, was employed for predicting the built-up area in Shenzhen in 2030. An almost threefold increase was observed in total built-up area from 421 km2 in 1995 to 1166 km2 in 2030, with the 2016 built-up area being 858 km2. Built-up areas, both present (2016) and projected (2030), were then used as the land cover input for flood hazard assessment based on a fuzzy comprehensive evaluation model, which classified the flood hazard into five levels. The analysis indicates that the built-up area subjected to the two highest flood hazard levels will increase by almost 88% (212 km2) from present to future. The approach presented here can be leveraged by policymakers to identify critical areas that should be prioritized for flood mitigation and protection actions to minimize potential losses.

scholarly journals Examining the Density and Diversity of Human Activity in the Built Environment: The Case of the Pearl River Delta, China

2020 ◽  
Vol 12 (9) ◽  
pp. 3700
Author(s):  
Miaoxi Zhao ◽  
Gaofeng Xu ◽  
Martin de Jong ◽  
Xinjian Li ◽  
Pingcheng Zhang
Keyword(s):  
Built Environment ◽  
Human Activity ◽  
Pearl River Delta ◽  
Positive Impact ◽  
River Delta ◽  
Pearl River ◽  
Rapid Urbanization ◽  
Land Use Efficiency ◽  
The Pearl River Delta ◽  
The Pearl River

Rapid urbanization in China has been accompanied by spatial inefficiency in patterns of human activity, of which ‘ghost towns’ are the most visible result. In this study, we measure the density and diversity of human activity in the built environment and relate this to various explanatory factors. Using the Pearl River Delta (PRD) as an empirical case, our research demonstrates the distribution of human activity by multi-source data and then explores its dynamics within these areas. This empirical study is comprised of two parts. The first part explores location information regarding human activity in urbanized areas and shows density and diversity. Regression models are applied to explore how density and diversity are affected by urban scale, morphology and by a city’s administrative level. Results indicate that: 1) cities with smaller populations are more likely to be faced with lower density and diversity, but they derive greater marginal benefits from improving land use efficiency; 2) the compactness of the layout of urban land, an index reflecting the plane shapes of the built environment, is highly correlated with density and diversity in built-up areas; and 3) the administrative importance of a city has a significant and positive impact on the density of human activity, but no obvious influence on its diversity.

Effects of urbanization and global climate change on regional climate in the Pearl River Delta and thermal comfort implications

2019 ◽  
Vol 39 (6) ◽  
pp. 2984-2997 ◽  
Author(s):  
Yongli Wang ◽  
Allen Chan ◽  
Gabriel Ngar‐Cheung Lau ◽  
Qingxiang Li ◽  
Yuanjian Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Thermal Comfort ◽  
Global Climate Change ◽  
Pearl River Delta ◽  
Global Climate ◽  
Regional Climate ◽  
River Delta ◽  
Pearl River ◽  
The Pearl River Delta ◽  
The Pearl River

scholarly journals Response of the Sea Breeze to Urbanization in the Pearl River Delta Region

2019 ◽  
Vol 58 (7) ◽  
pp. 1449-1463 ◽  
Author(s):  
Cheng You ◽  
Jimmy Chi-Hung Fung ◽  
Wai Po Tse
Keyword(s):  
Pearl River Delta ◽  
Coastal Region ◽  
Sea Breeze ◽  
River Delta ◽  
Pearl River ◽  
Pearl River Delta Region ◽  
Start Time ◽  
Rapid Urbanization ◽  
The Pearl River Delta ◽  
The Pearl River

AbstractThe Pearl River delta (PRD) region has undergone rapid urbanization since the 1980s, which has had significant effects on the sea-breeze circulation in this region. Because the sea breeze plays an important role in pollutant transportation and convective initiation in the PRD region, it is meaningful to study the effects of urbanization on the sea breeze. In this study, three numerical experiments were conducted from 2 June to 31 August 2010 with land-use data from 1988, 1999, and 2010. For each simulation, characteristics of the sea breeze such as the start time, end time, intensity, height, pumping ability, and inland penetration distance were quantified. By comparing the characteristics of the sea breeze in these simulations, its response to urbanization was quantified. The results show that urbanization enhances the duration, height, and intensity of the sea breeze but blocks its inland penetration. One physical mechanism is proposed to dynamically elucidate the response of the sea breeze to urbanization. Because the urban area in the PRD region is concentrated near the coast, urbanization imposes a positive heating gradient on the coastal region and a negative heating gradient on the region farther inland. The positive heating gradient may intensify the sea breeze, and the negative heating gradient may prevent the sea breeze from propagating farther inland.

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