scholarly journals Urbanization Enhanced Summertime Extreme Hourly Precipitation over the Yangtze River Delta

2020 ◽  
Vol 33 (13) ◽  
pp. 5809-5826 ◽  
Author(s):  
Xiaoling Jiang ◽  
Yali Luo ◽  
Da-Lin Zhang ◽  
Mengwen Wu
Keyword(s):  
Surface Temperature ◽  
Yangtze River ◽  
Late Summer ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
Rapid Urbanization ◽  
Hourly Precipitation ◽  
Increasing Trends ◽  
The Yrd ◽  
The Yangtze River Delta

AbstractAn extensive urban agglomeration has occurred over the Yangtze River delta (YRD) region of East China as a result of rapid urbanization since the middle 1990s. In this study, a 44-yr (i.e., 1975–2018) climatology of the summertime extreme hourly precipitation (EXHP; greater than the 90th percentile) over the YRD is analyzed, using historical land-use data, surface temperature, and hourly rain gauge observations, and then the relationship between rapid urbanization and EXHP changes is examined. Results show significant EXHP contrasts in diurnal variation and storm type roughly before and after middle July. That is, tropical cyclones (TCs) account for 16.4% of the total EXHP hours, 80.5% of which occur during the late summer, whereas non-TC EXHP accounts for 94.7% and 66.2% during the early and late summer, respectively. Increasing trends in occurrence frequency and amount of the non-TC and TC-induced EXHP are detected over the urban agglomeration. Statistically significant larger increasing trends in both the EXHP and surface temperature are observed at urban stations than those at the nearby rural stations. An analysis of 113 locally developed non-TC extreme rainfall events during 2011–18 summers also suggests the contribution of the urban heat island effects to the more occurrences of EXHP, especially over a band-shaped urban region where several major cities are distributed. This study reveals a significant correlation between rapid urbanization and increased EXHP during the past two decades over the YRD region. The results have important implications for understanding the impact of urbanization on EXHP changes in a warming climate.

scholarly journals Spatio-Temporal Variations of CO2 Emission from Energy Consumption in the Yangtze River Delta Region of China and Its Relationship with Nighttime Land Surface Temperature

2020 ◽  
Vol 12 (20) ◽  
pp. 8388
Author(s):  
Juchao Zhao ◽  
Shaohua Zhang ◽  
Kun Yang ◽  
Yanhui Zhu ◽  
Yuling Ma
Keyword(s):  
Surface Temperature ◽  
Co2 Emissions ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
Delta Region ◽  
Yangtze River Delta Region ◽  
The Yangtze River Delta

The rapid development of industrialization and urbanization has resulted in a large amount of carbon dioxide (CO2) emissions, which are closely related to the long-term stability of urban surface temperature and the sustainable development of cities in the future. However, there is still a lack of research on the temporal and spatial changes of CO2 emissions in long-term series and their relationship with land surface temperature. In this study, Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS) data, Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) composite data, energy consumption statistics data and nighttime land surface temperature are selected to realize the spatial informatization of long-term series CO2 emissions in the Yangtze River Delta region, which reveals the spatial and temporal dynamic characteristics of CO2 emissions, spatial autocorrelation distribution patterns and their impacts on nighttime land surface temperature. According to the results, CO2 emissions in the Yangtze River Delta region show an obvious upward trend from 2000 to 2017, with an average annual growth rate of 6.26%, but the growth rate is gradually slowing down. In terms of spatial distribution, the CO2 emissions in that region have significant regional differences. Shanghai, Suzhou and their neighboring cities are the main distribution areas with high CO2 emissions and obvious patch distribution patterns. From the perspective of spatial trend, the areas whose CO2 emissions are of significant growth, relatively significant growth and extremely significant growth account for 8.78%, 4.84% and 0.58%, respectively, with a spatial pattern of increase in the east and no big change in the west. From the perspective of spatial autocorrelation, the global spatial autocorrelation index of CO2 emissions in the Yangtze River Delta region in the past 18 years has been greater than 0.66 (p < 0.01), which displays significant positive spatial autocorrelation characteristics, and the spatial agglomeration degree of CO2 emissions continues to increase from 2000 to 2010. From 2000 to 2017, the nighttime land surface temperature in that region showed a warming trend, and the areas where CO2 emissions are positively correlated with nighttime land surface temperature account for 88.98%. The increased CO2 emissions lead to, to a large extent, the rise of nighttime land surface temperature. The research results have important theoretical and practical significance for the Yangtze River Delta region to formulate a regional emission reduction strategy.

scholarly journals Integrating Sustainability Assessment into Decoupling Analysis: A Focus on the Yangtze River Delta Urban Agglomerations

2020 ◽  
Vol 12 (19) ◽  
pp. 7872
Author(s):  
Yijia Huang ◽  
Jiaqi Zhang ◽  
Jinqun Wu
Keyword(s):  
Environmental Sustainability ◽  
Yangtze River ◽  
Sustainability Assessment ◽  
Yangtze River Delta ◽  
River Delta ◽  
The Yangtze River ◽  
Urban Agglomerations ◽  
Decoupling Analysis ◽  
The Yrd ◽  
The Yangtze River Delta

Rapid urbanization has led to a growing number of environmental challenges in large parts of China, where the Yangtze River Delta (YRD) urban agglomerations serve as a typical example. To evaluate the relationship between environmental sustainability gaps and urbanization in 26 cities of the YRD, this study revisited the environmental sustainability assessment (ESA) by combining the metrics of environmental footprints and planetary boundaries at the city level, and then integrated the footprint-boundary ESA framework into decoupling analysis. The results demonstrated considerable spatiotemporal heterogeneity in the environmental sustainability of water use, land use, carbon emissions, nitrogen emissions, phosphorus emissions and PM2.5 emissions across the YRD cities during the study period 2007–2017. Decoupling analysis revealed a positive sign that more than half of the 26 cities had achieved the decoupling of each category of environmental sustainability gaps from urbanization since 2014, especially for nitrogen and phosphorus emissions. On the basis of ESA and decoupling analysis, all the cities were categorized into six patterns, for which the optimal pathways towards sustainable development were discussed in depth. Our study will assist policy makers in formulating more tangible and differentiated policies to achieve decoupling between environmental sustainability gaps and urbanization.

scholarly journals Modeling of the anthropogenic heat flux and its effect on regional meteorology and air quality over the Yangtze River Delta region, China

2016 ◽  
Vol 16 (10) ◽  
pp. 6071-6089 ◽  
Author(s):  
Min Xie ◽  
Jingbiao Liao ◽  
Tijian Wang ◽  
Kuanguang Zhu ◽  
Bingliang Zhuang ◽  
...  
Keyword(s):  
Air Quality ◽  
Urban Areas ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
Vertical Movement ◽  
Anthropogenic Heat ◽  
The Yangtze River ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Abstract. Anthropogenic heat (AH) emissions from human activities caused by urbanization can affect the city environment. Based on the energy consumption and the gridded demographic data, the spatial distribution of AH emission over the Yangtze River Delta (YRD) region is estimated. Meanwhile, a new method for the AH parameterization is developed in the WRF/Chem model, which incorporates the gridded AH emission data with the seasonal and diurnal variations into the simulations. By running this upgraded WRF/Chem for 2 typical months in 2010, the impacts of AH on the meteorology and air quality over the YRD region are studied. The results show that the AH fluxes over the YRD have been growing in recent decades. In 2010, the annual-mean values of AH over Shanghai, Jiangsu and Zhejiang are 14.46, 2.61 and 1.63 W m−2, respectively, with the high value of 113.5 W m−2 occurring in the urban areas of Shanghai. These AH emissions can significantly change the urban heat island and urban-breeze circulations in the cities of the YRD region. In Shanghai, 2 m air temperature increases by 1.6 °C in January and 1.4 °C in July, the PBLH (planetary boundary layer height) rises up by 140 m in January and 160 m in July, and 10 m wind speed is enhanced by 0.7 m s−1 in January and 0.5 m s−1 in July, with a higher increment at night. The enhanced vertical movement can transport more moisture to higher levels, which causes the decrease in water vapor at ground level and the increase in the upper PBL (planetary boundary layer), and thereby induces the accumulative precipitation to increase by 15–30 % over the megacities in July. The adding of AH can impact the spatial and vertical distributions of the simulated pollutants as well. The concentrations of primary air pollutants decrease near the surface and increase at the upper levels, due mainly to the increases in PBLH, surface wind speed and upward air vertical movement. But surface O3 concentrations increase in the urban areas, with maximum changes of 2.5 ppb in January and 4 ppb in July. Chemical direct (the rising up of air temperature directly accelerates surface O3 formation) and indirect (the decrease in NOx at the ground results in the increase in surface O3) effects can play a significant role in O3 changes over this region. The meteorology and air pollution predictions in and around large urban areas are highly sensitive to the anthropogenic heat inputs, suggesting that AH should be considered in the climate and air quality assessments.

scholarly journals Integrated studies of a regional ozone pollution synthetically affected by subtropical high and typhoon system in the Yangtze River Delta region, China

2016 ◽  
Author(s):  
Lei Shu ◽  
Min Xie ◽  
Tijian Wang ◽  
Pulong Chen ◽  
Yong Han ◽  
...  
Keyword(s):  
Yangtze River ◽  
Western Pacific Subtropical High ◽  
Yangtze River Delta ◽  
River Delta ◽  
Western Pacific ◽  
Subtropical High ◽  
The Yangtze River ◽  
Observational Analysis ◽  
The Yrd ◽  
The Yangtze River Delta

Abstract. Severe high ozone (O3) episodes usually have close relations to synoptic systems. A regional continuous O3 pollution episode is detected over the Yangtze River Delta (YRD) region in China during August 7–12, 2013, in which the O3 concentrations in more than half of the cities exceeding the national air quality standard. The maximum hourly concentration of O3 reaches 167.1 ppb. By means of the observational analysis and the WRF/CMAQ numerical simulation, the characteristics and the essential impact factors of the typical regional O3 pollution is integratedly investigated. The observational analysis shows that the atmospheric subsidence dominated by Western Pacific subtropical high plays a crucial role in the formation of high-level O3. The favorable weather conditions, such as extremely high temperature, low relative humidity and weak wind speed, caused by the abnormal strong subtropical high are responsible for the trapping and the chemical production of O3 in the boundary layer. In addition, when the YRD cities at the front of Typhoon Utor, the periphery circulation of typhoon system can enhance the downward airflows and cause worse air pollution. But when the typhoon system weakens the subtropical high, the prevailing southeasterly surface wind leads to the mitigation of the O3 pollution. The Integrated Process Rate (IPR) analysis incorporated in CMAQ is applied to further illustrate the combined influence of subtropical high and typhoon system in this O3 episode. The results show that the vertical diffusion (VDIF) and the gas-phase chemistry (CHEM) are two major contributors to O3 formation. During the episode, the contributions of VDIF and CHEM to O3 maintain the high values over 10 ppb/h in Shanghai, Hangzhou, and Nanjing. On August 10–11, the cities close to the sea are apparently affected by the typhoon system, with the contribution of VDIF increasing to 28.45 ppb/h in Shanghai and 19.76 ppb/h in Hangzhou. When the YRD region is under the control of the typhoon system, the contribution values of all individual processes decrease to a low level in all cities. These results provide an insight for the O3 pollution synthetically impacted by the Western Pacific subtropical high and the tropical cyclone system.

scholarly journals Source, transport and impacts of a heavy dust event in the Yangtze River Delta, China in 2011

2013 ◽  
Vol 13 (8) ◽  
pp. 21507-21540
Author(s):  
X. Fu ◽  
S. X. Wang ◽  
Z. Cheng ◽  
J. Xing ◽  
B. Zhao ◽  
...  
Keyword(s):  
Air Quality ◽  
Yangtze River ◽  
Eastern China ◽  
Yangtze River Delta ◽  
River Delta ◽  
Dust Particles ◽  
The Yangtze River ◽  
Dust Event ◽  
The Yrd ◽  
The Yangtze River Delta

Abstract. During 1 to 6 May 2011, a dust event was observed in the Yangtze River Delta region (YRD). The highest PM10 concentration reached over 1000 μg m−3 and the visibility was below 3 km. In this study, the Community Multi-scale Air Quality modeling system (CMAQ5.0) coupled with an in-line windblown dust model was used to simulate the formation, spatial and temporal characteristics of this dust event, and analyze its impacts on deposition and photochemistry. The threshold friction velocity for loose smooth surface in the dust model was revised based on Chinese data to improve the model performance. The comparison between predictions and observations indicates the revised model can reproduce the transport and pollution of the event. The simulation results show that the dust event was affected by formation and transport of Mongolian cyclone and cold air. Totally about 695 kt dust particles (PM10) were emitted in Xinjiang Province and Mongolia during 28 to 30 April, the dust band swept northern, eastern China and then arrived in the YRD region on 1 May 2011. The transported dust particles increased the mean surface layer concentrations of PM10 in the YRD region by 372% during 1 to 6 May and the impacts weakened from north to south due to the removal of dust particles along the path. Accompanied by high PM concentration, the dry deposition, wet deposition and total deposition of PM10 in the YRD reached 184.7 kt, 172.6 kt and 357.32 kt, respectively. These deposited particles are very harmful because of their impacts on urban environment as well as air quality and human health when resuspending in the atmosphere. Due to the impacts of mineral dust on atmospheric photolysis, the concentrations of O3 and OH were reduced by 1.5% and 3.1% in the whole China, and by 9.4% and 12.1% in the YRD region, respectively. The work of this manuscript is meaningful for understanding the dust emissions in China as well as for the application of CMAQ in Asia. It is also helpful to understand the formation mechanism and impacts of dust pollution in the YRD.

scholarly journals Enhanced sulfate formation through SO<sub>2</sub>+NO<sub>2</sub> heterogeneous reactions during heavy winter haze in the Yangtze River Delta region, China

2019 ◽  
Author(s):  
Ling Huang ◽  
Jingyu An ◽  
Bonyoung Koo ◽  
Greg Yarwood ◽  
Rusha Yan ◽  
...  
Keyword(s):  
Air Quality ◽  
Yangtze River ◽  
Yangtze River Delta ◽  
Heterogeneous Reactions ◽  
Ammonia Emissions ◽  
The Yangtze River ◽  
Uptake Mechanism ◽  
Sulfate Formation ◽  
The Yrd ◽  
The Yangtze River Delta

Abstract. Rapid sulfate formation is recognized as key characteristics of severe winter haze in China. However, air quality models tend to underestimate sulfate formation during heavy haze periods and heterogeneous formation pathways have been proposed as promising mechanisms to reduce gaps between observation and model simulation. In this study, we implemented a reactive SO2 uptake mechanism through the SO2+NO2 heterogeneous reactions in the Comprehensive Air Quality Model with extensions (CAMx) to improve simulation of sulfate formation in the Yangtze River Delta (YRD) region for the first time. Parameterization of the SO2+NO2 heterogeneous reactions is based on observations in Beijing and considered both impact of relative humidity and aerosol pH on sulfate formation. Ammonia is reported to be critical for the formation of secondary inorganic aerosols and estimation of ammonia emissions is usually associated with large uncertainties. Sensitivity tests were conducted to evaluate the importance of the SO2+NO2 heterogeneous reactions as well as ammonia emissions on modelled sulfate concentrations during a period with several heavy haze episodes in the YRD region. Base case model results show large underestimation of sulfate concentrations by 36 % under polluted conditions in the YRD region. Adding the SO2+NO2 heterogeneous reactions or doubling ammonia emissions alone leads to slight model improvement (~ 6 %) on simulated sulfate concentrations in the YRD region. However, model performance significantly improved when both the SO2+NO2 heterogeneous reactions and doubled ammonia emissions were included in the simulation: predicted sulfate concentrations during polluted periods increased from 23.1 µg m−3 in the base scenario to 29.1 µg m−3 (representing an increase of 26 %). Aerosol pH is crucial for the SO2+NO2 heterogeneous reactions and our calculated aerosol pH is always acidic and increased by 0.7 with doubled ammonia emissions. Modelling results also show that this reactive SO2 uptake mechanism enhanced sulfate simulations by 1 to 5 µg m−3 for the majority of eastern and central part of China, with more than 20 µg m−3 increase of sulfate concentrations over the north-eastern plateau. These findings suggest that the SO2+NO2 heterogeneous reactions could be important for sulfate formation in the YRD region as well as other parts of China. In addition, ammonia emissions need to be carefully estimated. More studies are needed to improve the parameterization of the SO2+NO2 heterogeneous reactions based on local data further evaluate this mechanism in other regions. Substantial efforts are needed to improve the accuracy of ammonia emissions inventory.

What Limits the Benefits of Land-Lost Farmers in Chinese Courts? An Investigation of Chinese Land Acquisition and Resettlement Cases in the Yangtze River Delta

SAGE Open ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 215824402110332
Author(s):  
Wenzhang Zhou ◽  
Haijun Bao
Keyword(s):  
Yangtze River ◽  
Yangtze River Delta ◽  
Land Acquisition ◽  
Land Resources ◽  
The Yangtze River ◽  
Rapid Urbanization ◽  
Interdisciplinary Work ◽  
Relationship Of ◽  
The Relationship ◽  
The Yangtze River Delta

Due to China’s rapid urbanization, the growing presence of land-lost farmers in land acquisition and resettlement (LAR) cases has led to major practical and academic concerns. However, few studies have focused on administration policy restrictions and how they affect land-lost farmers in Chinese courts for land resources. Based on the quantitative analysis and case studies involving 2,242 administrative LAR cases, this interdisciplinary work examines how administrative bureaucracy affects public departments’ ability to win in court. The findings of this study are twofold. First, in the relationship of Tiao, public departments at the top of the hierarchy can use administration policies to screen conflicts, which can increase the win rate of LAR cases. Second, in the relationship of Kuai, authorities’ relationships limit the investment in administration policies, which in turn decide the utility of administration policies in LAR cases. The findings can facilitate the implementation of appropriate administrative and judicial measures in different departments to promote land-lost farmers.

scholarly journals An important mechanism of regional O<sub>3</sub> transport for summer smog over the Yangtze River Delta in eastern China

2018 ◽  
Vol 18 (22) ◽  
pp. 16239-16251 ◽  
Author(s):  
Jun Hu ◽  
Yichen Li ◽  
Tianliang Zhao ◽  
Jane Liu ◽  
Xiao-Ming Hu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Yangtze River ◽  
Eastern China ◽  
Yangtze River Delta ◽  
The Yangtze River ◽  
Convective Boundary ◽  
Summer Smog ◽  
The Yrd ◽  
Surface O3 ◽  
The Yangtze River Delta

Abstract. Severe ozone (O3) pollution episodes plague a few regions in eastern China at certain times of the year, e.g., the Yangtze River Delta (YRD). However, the formation mechanisms, including meteorological factors, contributing to these severe pollution events remain elusive. A severe summer smog stretched over the YRD region from 22 to 25 August 2016. This event displayed hourly surface O3 concentrations that exceeded 300 µg m−3 on 25 August in Nanjing, an urban area in the western YRD. The weather pattern during this period was characterized by near-surface prevailing easterly winds and continuous high air temperatures. The formation mechanism responsible for this O3 pollution episode over the YRD region, particularly the extreme values over the western YRD, was investigated using observation data and by running simulations with the Weather Research and Forecasting model with Chemistry (WRF-Chem). The results showed that the extremely high surface O3 concentration in the western YRD area on 25 August was largely due to regional O3 transport in the nocturnal residual layer (RL) and the diurnal change in the atmospheric boundary layer. On 24 August, high O3 levels, with peak values of 220 µg m−3, occurred in the daytime mixing layer over the eastern YRD region. During nighttime from 24 to 25 August, a shallow stable boundary layer formed near the surface which decoupled the RL above it from the surface. Ozone in the decoupled RL remained quite constant, which resulted in an O3-rich “reservoir” forming in this layer. This reservoir persisted due to the absence of O3 consumption from nitrogen oxide (NO) titration or dry deposition during nighttime. The prevailing easterly winds in the lower troposphere governed the regional transport of this O3-rich air mass in the nocturnal RL from the eastern to the western YRD. As the regional O3 transport reached the RL over the western YRD, O3 concentrations in the RL accumulated and rose to 200 µg m−3 over the western Nanjing site during the sunrise hours on 25 August. The development of the daytime convective boundary layer after sunrise resulted in the disappearance of the RL, as the vertical mixing in the convective boundary layer uniformly redistributed O3 from the upper levels via the entrainment of O3-rich RL air down to the O3-poor air at the ground. This net downward transport flux reached up to 35 µg m−3 h−1, and contributed a considerable surface O3 accumulation, resulting in severe daytime O3 pollution during the summer smog event on 25 August in the western YRD region. The mechanism of regional O3 transport through the nocturnal RL revealed in this study has great implications regarding understanding O3 pollution and air quality change.

scholarly journals Spatiotemporal distribution and trend of COVID-19 in the Yangtze River Delta region of the People’s Republic of China

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Lei Ye ◽  
Lingqian Hu
Keyword(s):  
Yangtze River ◽  
Yangtze River Delta ◽  
Hubei Province ◽  
River Delta ◽  
People’S Republic Of China ◽  
The Yangtze River ◽  
People's Republic Of China ◽  
Republic Of China ◽  
The Yrd ◽  
The Yangtze River Delta

An outbreak of atypical pneumonia, now called COVID-19 and known to be caused by the novel coronavirus SARS-CoV-2, first detected in Wuhan, Hubei Province of the People’s Republic of China in December 2019 and afterwards rapidly spread worldwide. Wuhan and the Yangtze River Delta (YRD) region implemented first-level public health emergency responses to stop the spread of the virus on January 23rd, 2020. We tracked the geographical gravity centre of the disease and calculated spatial autocorrelation to explore the spatiotemporal patterns of distribution of imported and locally disseminated COVID-19 cases under the emergency-response control measure. We also applied polynomial regression analysis to estimate the trend of the COVID-19 in the YRD region before and after the control activities against the spread of the infection were instituted. The results show that the control measures applied have been effective. And, in the YRD region, areas with a large influx of population flow from Wuhan and Hubei Province had high risks of COVID-19. Therefore, identification of the spatiotemporal trends should be the first step when developing effective policies to manage and control any new epidemic. The results are not only informative locally but also useful for the rest of the world.

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