scholarly journals Differentiated Effects of Urbanization on Precipitation in South China

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1386
Author(s):  
Lingli Fan ◽  
Guangya Zhang ◽  
Jianjun Xu
Keyword(s):  
Water Vapor ◽  
South China ◽  
Rural Areas ◽  
Convective Available Potential Energy ◽  
Precipitation Trend ◽  
Rapid Urbanization ◽  
Sea Breezes ◽  
Moisture Recycling ◽  
Urban Cluster ◽  
Cluster A

In this paper, precipitation data from the Tropical Rainfall Measuring Mission (TRMM), together with atmospheric reanalysis data, are employed to identify warm-season precipitation (1998–2014) changes and their association with rapid urbanization in south China. Three urban clusters (Chenyu, Yangtze Delta, and Fujian Guangdong coast) are focused. The results reveal that, for the inland Chengyu urban cluster, a lack of precipitation trend is likely due to insignificant trends in convective available potential energy (CAPE) and total column water vapor (TCWV). They are likely resulted from a reduced local moisture recycling in urban areas, balanced by an increased evapotranspiration of rural areas, together with a stable advection of water vapor input. For the Yangtze River Delta urban cluster, a negative trend in precipitation is associated with a slightly decreased CAPE and an increased TCWV, but is very likely related to urbanization induced an increased planetary boundary layer (PBL) and reduced land surface evaporation. For the Fujian Guangdong coast urban cluster, a marked positive precipitation trend is well explained by positive trends in CAPE and TCWV. The increased precipitation likely benefits from enhanced moisture recycling due to improved vegetation cover in rural areas, and enhanced advection moisture inputs due to urbanization along the coast. These results suggest urbanization effects on precipitation vary with regional conditions. In the coastal area, urbanization enhances sea breezes, which may benefit precipitation if sea breezes go along with the prevailing moisture. In inland area, urbanization likely leads to a warmer-dryer climate if large-scale land cover keeps stationary.

scholarly journals Observed Link of Extreme Hourly Precipitation Changes to Urbanization over Coastal South China

2019 ◽  
Vol 58 (8) ◽  
pp. 1799-1819 ◽  
Author(s):  
Mengwen Wu ◽  
Yali Luo ◽  
Fei Chen ◽  
Wai Kin Wong
Keyword(s):  
South China ◽  
Extreme Rainfall ◽  
Rapid Urbanization ◽  
Extreme Rainfall Events ◽  
Convective Initiation ◽  
Rainfall Events ◽  
Hourly Precipitation ◽  
Urban Cluster ◽  
Wide Range ◽  
Extreme Rain

AbstractUnderstanding changes in subdaily rainfall extremes is critical to urban planners for building more sustainable and resilient cities. In this study, the hourly precipitation data in 1971–2016 from 61 rain gauges are combined with historical land-use change data to investigate changes in extreme hourly precipitation (EXHP) in the Pearl River delta (PRD) region of South China. Also, 120 extreme rainfall events (EXREs) during 2011–16 are analyzed using observations collected at densely distributed automatic weather stations and radar network. Statistically significant increase of hourly precipitation intensity leads to higher annual amounts of both total and extreme precipitation over the PRD urban cluster in the rapid urbanization period (about 1994–2016) than during the preurbanization era (1971 to about 1993), suggesting a possible link between the enhanced rainfall and the rapid urbanization. Those urbanization-related positive trends are closely related to more frequent occurrence of abrupt rainfall events with short duration (≤6 h) than the continuous or growing rainfall events with longer duration. The 120 EXREs in 2011–16 are categorized into six types according to the originating location and movement of the extreme-rain-producing storms. Despite the wide range of synoptic backgrounds and seasons, rainfall intensification by the strong urban heat island (UHI) effect is a clear signal in all the six types, especially over the inland urban cluster with prominent UHIs. The UHI thermal perturbation probably plays an important role in the convective initiation and intensification of the locally developed extreme-rain-producing storms during the daytime.

scholarly journals Synergistic Modulations of Large-Scale Synoptic Patterns and Local-Scale Urbanization Effects on Summer Rainfall in South China

2021 ◽  
Vol 3 ◽  
Author(s):  
Minxuan Zhang ◽  
Wanju Li ◽  
Xueyan Bi ◽  
Lian Zong ◽  
Yanhao Zhang ◽  
...  
Keyword(s):  
South China ◽  
Rural Areas ◽  
Large Scale ◽  
Summer Precipitation ◽  
Guangdong Province ◽  
Northwestern Pacific ◽  
Observation Data ◽  
Rapid Urbanization ◽  
Weather Types ◽  
Frequency Changes

Using the ERA5 (the fifth major global reanalysis produced by the European Centre for Medium-Range Weather Forecasts) data and the T-PCA (Principal Component Analysis in T-mode) objective classification method to classify the 850-hPa geopotential height, we summarize four conceptual models of large-scale synoptic weather types over East Asia. By combining this with the daily precipitation observation data of 36 meteorological stations in Guangdong, South China, during summer (June to August) of 2014–2018, we found that summer precipitation in Guangdong Province is closely related to the position of the northwestern Pacific subtropical high and the strong upward motion of the warm airflow over the Pearl River Delta. It is further revealed the regulation effect of different weather patterns on summer precipitation in Guangdong Province and their urban–rural differences. More specifically, both urban and rural areas have a decreasing proportion of light rainfall and an increasing proportion of heavy and torrential rainfall, which are mainly regulated by the trend of frequency changes of four different weather types: Type 1 (47.39%) and Type 2 (32.39%) days are decreasing year by year, modulating the trend of light rainfall, while Type 3 (13.26%) and Type 4 (6.96%) days are steadily increasing, dominating the trend of heavy rainfall. In addition, it was further found that the frequency of light rainfall is decreasing more significantly in cities compared to that in rural areas, while the proportion of heavy and stormy rainfall is increasing more significantly, which is closely related to the effects of rapid urbanization.

scholarly journals A 7-Year Climatology of Warm-Sector Heavy Rainfall over South China during the Pre-Summer Months

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 914
Author(s):  
Tao Chen ◽  
Da-Lin Zhang
Keyword(s):  
South China ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Convective Available Potential Energy ◽  
Potential Temperature ◽  
Vertical Wind Shear ◽  
Precipitable Water ◽  
Atmospheric Parameter ◽  
Low Level ◽  
Warm Sector

In view of the limited predictability of heavy rainfall (HR) events and the limited understanding of the physical mechanisms governing the initiation and organization of the associated mesoscale convective systems (MCSs), a composite analysis of 58 HR events over the warm sector (i.e., far ahead of the surface cold front), referred to as WSHR events, over South China during the months of April to June 2008~2014 is performed in terms of precipitation, large-scale circulations, pre-storm environmental conditions, and MCS types. Results show that the large-scale circulations of the WSHR events can be categorized into pre-frontal, southwesterly warm and moist ascending airflow, and low-level vortex types, with higher frequency occurrences of the former two types. Their pre-storm environments are characterized by a deep moist layer with >50 mm column-integrated precipitable water, high convective available potential energy with the equivalent potential temperature of ≥340 K at 850 hPa, weak vertical wind shear below 400 hPa, and a low-level jet near 925 hPa with weak warm advection, based on atmospheric parameter composite. Three classes of the corresponding MCSs, exhibiting peak convective activity in the afternoon and the early morning hours, can be identified as linear-shaped, a leading convective line adjoined with trailing stratiform rainfall, and comma-shaped, respectively. It is found that many linear-shaped MCSs in coastal regions are triggered by local topography, enhanced by sea breezes, whereas the latter two classes of MCSs experience isentropic lifting in the southwesterly warm and moist flows. They all develop in large-scale environments with favorable quasi-geostrophic forcing, albeit weak. Conceptual models are finally developed to facilitate our understanding and prediction of the WSHR events over South China.

scholarly journals China: A New Trajectory Prioritizing Rural Rather Than Urban Development?

Land ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 514
Author(s):  
Hongzhang Xu ◽  
Jamie Pittock ◽  
Katherine A. Daniell
Keyword(s):  
Rural Development ◽  
Development Strategy ◽  
Rural Community ◽  
Rural Areas ◽  
Urban Policy ◽  
Local Governance ◽  
National Development ◽  
Rapid Urbanization ◽  
Rural And Urban ◽  
Global Concern

The adverse effects of rapid urbanization are of global concern. Careful planning for and accommodation of accelerating urbanization and citizenization (i.e., migrants gaining official urban residency) may be the best approach to limit some of the worst impacts. However, we find that another trajectory may be possible: one linked to the rural development plan adopted in the latest Chinese national development strategy. This plan aims to build rural areas as attractive areas for settlement by 2050 rather than to further urbanize with more people in cities. We assess the political motivations and challenges behind this choice to develop rural areas based on a literature review and empirical case analysis. After assessing the rural and urban policy subsystem, we find five socio-political drivers behind China’s rural development strategy, namely ensuring food security, promoting culture and heritage, addressing overcapacity, emphasizing environmental protection and eradicating poverty. To develop rural areas, China needs to effectively resolve three dilemmas: (1) implementing decentralized policies under central supervision; (2) deploying limited resources efficiently to achieve targets; and (3) addressing competing narratives in current policies. Involving more rural community voices, adopting multiple forms of local governance, and identifying and mitigating negative project impacts can be the starting points to manage these dilemmas.

scholarly journals Placemaking Interventions in Palestine as Demonstration Effects on the Ground

2020 ◽  
pp. 167-176
Author(s):  
Ahmad El-Atrash
Keyword(s):  
Rural Areas ◽  
West Bank ◽  
Gaza Strip ◽  
Building Design ◽  
Public Spaces ◽  
The West ◽  
Rapid Urbanization ◽  
Urban And Rural Areas ◽  
Privately Owned

The urban development and rapid urbanization that the West Bank, including occupied East Jerusalem and Gaza Strip have recently encountered have adversely affected the quality and availability of open spaces inside the Palestinian urban and rural areas. Public spaces are fundamental in the lives of any community striving to achieve a sustainable and inclusive environment and improve the quality of life of its inhabitants. In that respect, the prevailing planning practices fall short in terms of adequately addressing the provision of public spaces. Laws and regulations are designed to focus on limited physical properties of buildings (e.g. building design, elevation, heights, setbacks, parking, etc.,) with little or no attention to the residual space, inevitably, created between those blocks. Lands are chiefly privately owned, and considered of a very high value due to the artificial land scarcity phenomenon resulted from the geo-political classification of the West Bank Existing public spaces are not welcoming to the general public. Spaces are misplaced and scattered, they offer pre-defined activities and an inflexible environment. Many parts of the society feel alienated to such public spaces, created by a top-down process with minimal integration of their needs and aspirations.

scholarly journals The Impacts of Rapid Urbanization on the Thermal Environment: A Remote Sensing Study of Guangzhou, South China

2012 ◽  
Vol 4 (7) ◽  
pp. 2033-2056 ◽  
Author(s):  
Yongzhu Xiong ◽  
Shaopeng Huang ◽  
Feng Chen ◽  
Hong Ye ◽  
Cuiping Wang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
South China ◽  
Thermal Environment ◽  
Rapid Urbanization

On the Localized Extreme Rainfall over the Great Bay Area in South China with Complex Topography and Strong UHI Effects

2021 ◽  
Author(s):  
Xiaoyan Sun ◽  
Yali Luo ◽  
Xiaoyu Gao ◽  
Mengwen Wu ◽  
Mingxin Li ◽  
...  
Keyword(s):  
South China ◽  
Global Analysis ◽  
Urban Canopy ◽  
Extreme Rainfall ◽  
Urban Agglomeration ◽  
Convective Initiation ◽  
Sea Breezes ◽  
Bay Area ◽  
Great Bay ◽  
Hourly Rainfall

AbstractIn this study, high-resolution surface and radar observations are used to analyze 24 localized extreme hourly rainfall (EXHR, > 60mm/h) events with strong urban heat island (UHI) effects over the Great Bay Area (GBA) in South China during 2011-2016 warm seasons. Quasi-idealized, convection-permitting ensemble simulations driven by diurnally varying lateral boundary conditions, which are extracted from the composite global analysis of 3-5 June 2013, are then conducted with a multi-layer urban canopy model to unravel the influences of the UHI and various surface properties nearby on the EXHR generation in a complex geographical environment with sea-land contrast, topography, and vegetation variation. Results show that EXHR is mostly distributed over the urban agglomeration and within about 40 km on its downwind side, and produced during the afternoon-to-evening hours by short-lived meso-γ to β-scale storms. On the EXHR days, the GBA is featured by a weak-gradient environment with abundant moisture, and a weak southwesterly flow prevailing in the boundary layer (BL). The UHI effects lead to the development of a deep mixed layer with “warm bubbles” over the urban agglomeration, in which the lower-BL convergence and BL-top divergence is developed, assisting in convective initiation. Such urban BL processes and associated convective development with moisture supply by the synoptic low-level southwesterly flow are enhanced by orographically increased horizontal winds and sea breezes under the influence of the herringbone coastline, thereby increasing the inhomogeneity and intensity of rainfall production over the “Π-shaped” urban clusters. Vegetation variations are not found to be an important factor in determining the EXHR production over the region.

Urbanization and The Dynamics of Change in the Sahel

2021 ◽  
pp. 708-728
Author(s):  
Florence Boyer ◽  
David Lessault
Keyword(s):  
Population Growth ◽  
Rural Areas ◽  
Demographic Transition ◽  
School Health ◽  
The State ◽  
Future Research ◽  
Rapid Urbanization ◽  
The City ◽  
Contemporary Context

Since independence, Sahelian cities have been experiencing continuous and increasingly strong population growth, linked to migration and to an unfinished demographic transition. In contexts of rapid urbanization, facilities, infrastructure, and services (school, health, sanitation, etc.) are deficient, and a transfer of poverty from rural areas to cities takes place. Sahelian cities are also marked by the youthfulness of their populations, and an important area for research are the questions of what the city does to youth, and what youth does to the city. Knowledge of Sahelian cities remains fragmented. If the dynamics and challenges of capitals such as Dakar, Ouagadougou, or Bamako are fairly well known, those of N’Djamena, Niamey, or Nouakchott are less so. There are few studies of small and medium-sized cities, and these are in need of updating in the contemporary context of decentralization. This chapter surveys the state of knowledge of urbanization in the Sahel, and suggests directions for future research.

From Rural Majority to Urban Majority Africans

2018 ◽  
pp. 1505-1526
Author(s):  
Umar G. Benna
Keyword(s):  
Work Environment ◽  
Rural Areas ◽  
Research Method ◽  
Digital Transformation ◽  
Future Research ◽  
Exploratory Research ◽  
Online Questionnaire ◽  
Rapid Urbanization ◽  
High Population Growth

Africa is experiencing triple processes of high population growth, rapid urbanization, and digital transformation. The undercurrents of these processes suggest that the continent is turning from rural majority to urban majority, and this situation raises the question of where will this majority work? Arab Spring and the turbulent situation in the Middle East suggest what could be the result of inaction. This chapter attempts to answer this question by using exploratory research method to highlight the potential role of mainly young entrepreneurs to define, through online questionnaire responses, their preferred terrain of workplace creation in local areas, cities, rural areas and in the diverse regions of Africa as well as on the ubiquitous online work environment extending from home to anywhere in the continent. The chapter ends with a review of the observations and suggestions about future research.

scholarly journals Influence of Arctic Oscillation on Frequency of Wintertime Fog Days in Eastern China

Atmosphere ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 162
Author(s):  
Peng Liu ◽  
Mingyue Tang ◽  
Huaying Yu ◽  
Ying Zhang
Keyword(s):  
Water Vapor ◽  
South China ◽  
Arctic Oscillation ◽  
North China ◽  
Eastern China ◽  
Reanalysis Data ◽  
Positive Phase ◽  
Westerly Jet ◽  
Environmental Prediction ◽  
Fog Days

The influence of Arctic Oscillation (AO) on the frequency of wintertime fog days in eastern China is studied based on the winter AO index, the wintertime fog-day data of national stations in China, and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data from 1954 to 2007. The results show that heavy fog and light fog are more likely to occur during winter in eastern China with the strong interannual variability. During the winter with the positive-phase AO, there are more days of heavy fog in North China but less in South China, while light fog days become more in the whole of eastern China. It is mainly because that when AO is in the positive phase, the pressure in the polar region decreases at 500 hPa; the pressure in East Asia increases anomalously; the East Asian trough decreases; and the low-level westerly jet moves northward, preventing the northwesterly cold air from moving southward. Therefore, the whole eastern China gets warmer and wetter air, and there are more light fog days with the enhanced water vapor. However, the atmosphere merely becomes more towards unstable in South China, where the precipitation increases but the heavy fog days decreases. Nevertheless, heavy fog days increase with the water vapor in North China because of moving towards a stable atmosphere, which is formed by the anomalous downdrafts north of the precipitation center in South China. When AO is in the negative phase, the situation is basically opposite to that in the positive phase, but the variations of the corresponding fog days and circulations are weaker than those in the AO-positive-phase winter, which may be related to the nonlinear effect of AO on climate.

Sign in / Sign up

Export Citation Format

Share Document