scholarly journals Diverse response of surface ozone to COVID-19 lockdown in China

2021 ◽  
Author(s):  
Yiming Liu ◽  
Tao Wang ◽  
Trissevgeni Stavrakou ◽  
Nellie Elguindi ◽  
Thierno Doumbia ◽  
...  
Keyword(s):  
South China ◽  
Emission Reduction ◽  
North China ◽  
Surface Ozone ◽  
Cloud Fraction ◽  
Central China ◽  
Lower Atmosphere ◽  
Boundary Layer Height ◽  
Volatile Organic ◽  
Complex Dependence

<p>Ozone (O<sub>3</sub>) is a key oxidant and pollutant in the lower atmosphere. Significant increases in surface O<sub>3</sub> have been reported in many cities during the COVID-19 lockdown. Here we conduct comprehensive observation and modeling analyses of surface O<sub>3</sub> across China for periods before and during the lockdown. We find that daytime O<sub>3</sub> decreased in the subtropical south, in contrast to increases in most other regions. Meteorological changes and emission reductions both contributed to the O<sub>3</sub> changes, with a larger impact from the former especially in central China. The southward-shifted wind with increased temperature, enhanced planetary boundary layer height, decreased cloud fraction and precipitation favored the O<sub>3</sub> increase in north and central China, while the northward-shifted wind with decreased temperature and then biogenic volatile organic compounds (VOCs) emissions, increased cloud fraction and precipitation reduced O<sub>3</sub> in south China. As for the emission reduction, the drop in nitrogen oxide (NO<sub>x</sub>) emission contributed to O<sub>3</sub> increases in populated regions, whereas the reduction in VOCs contributed to O<sub>3</sub> decreases across the country. Due to a decreasing level of NO<sub>x</sub> saturation from north to south, the emission reduction in NO<sub>x</sub> (46%) and VOC (32%) contributed to net O<sub>3</sub> increases in north China; the opposite effects of NO<sub>x</sub> decrease (49%) and VOC decrease (24%) balanced out in central China, whereas the comparable decreases (45-55%) in the two precursors contributed to net O<sub>3</sub> declines in south China. Our study highlights the complex dependence of O<sub>3</sub> on its precursors and the importance of meteorology in the short-term O<sub>3</sub> variability.</p>

scholarly journals Studies on the Climate Effects of Black Carbon Aerosols in China and Their Sensitivity to Particle Size and Optical Parameters

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Xingxing Ma ◽  
Hongnian Liu ◽  
Xueyuan Wang ◽  
Zhen Peng
Keyword(s):  
Particle Size ◽  
South China ◽  
Radiative Forcing ◽  
North China ◽  
Central China ◽  
East China ◽  
Optical Parameters ◽  
Climate Effects ◽  
Clear Sky ◽  
Bc Aerosols

In this paper, based on the principle of Mie scattering, we calculated the optical parameters of BC aerosols at different scales and then applied the new optical parameters to simulate the BC aerosols concentration distribution, radiative forcing, and their climate effects. We also compared the results of optical parameters of BC aerosols with homogeneous scales and analyzed the effect on climate. Compared with the conventional uniform-scheme optical parameterization, the concentrations of the first mode of BC aerosols simulated with the optical parameters that were recalculated based on the particle size are significantly higher, while the concentrations of the other modes and the total of BC aerosols are lower. In the respective of statistics, the changes of column burdens of BC in four modes are 0.085, −0.095, −0.089, −0.054 mg/m2. The clear-sky TRF of BC are weakened in the value of 0.03 W/m2 averaged over the domain, while the all-sky TRF of BC are enhanced of  0.06 W/m2 in general. The warming effect of BC becomes weaker when using the new scheme by −0.04 K to −0.24 K. When using the new optical parameters scheme, the regional average surface concentrations of BC in four modes are 0.372, 0.264, 0.055 and 0.004 μg/m3, respectively. Especially, the first and the second mode account for as large as 53% and 38%. The surface concentration and column burden of total BC are 0.69 μg/m3 and 0.28 mg/m2 can be dropped. The regional average direct RFs of BC at the top of the atmosphere are 0.49 W/m2 under clear-sky and 0.36 W/m2 under all-sky averaged over the domain. Over most areas of central China, North China, and East China, BC may increase the temperature in a range of 0.05∼0.15 K, while over South China, BC shows cooling effect. In average, the precipitation variations caused by BC over East China, North China, South China, and Northeast China are −0.83, −0.05, −0.11, and −0.13 mm/d, respectively. As a whole, the variations of circulation, pressure, and temperature show a good correspondence.

Some Aspects of Chinese Religious Practices and Customs in Singapore and Malaysia

1981 ◽  
Vol 12 (1) ◽  
pp. 133-141 ◽  
Author(s):  
Tadao Sakai
Keyword(s):  
Southeast Asia ◽  
South China ◽  
Religious Beliefs ◽  
Chinese Culture ◽  
North China ◽  
The Other ◽  
Central China ◽  
Asian Context ◽  
The One ◽  
The Relationship

This paper is a summary of my recent studies on the Taoist creed and common Chinese religious beliefs, in particular the religious customs of poeh (the practice of seeking divination) and the worship of the local god of the soil. While a number of papers have been published by scholars from the Singapore-Malaysia region, their findings have been somewhat limited in scope because they were confined to the Southeast Asian context. My study will be broader in scope. It will cover the relationship between the Chinese culture of China itself and that of Southeast Asia. In other words, this paper will give (1) a comparison between the cultural styles of North China, South, and Central China, (2) a study of Chinese culture in Southeast Asia viewed as an extension of the culture of South China, especially the provinces of Fukien and Kwangtung, and (3) a summary of my research on the conflict between Chinese culture in China on the one hand and that of the Singapore-Malaysia region on the other.

Spatiotemporal pattern mining of drought in the last 40 years in China based on the SPEI index and space-time cube

2021 ◽  
Author(s):  
Dehe Xu ◽  
Qi Zhang ◽  
Yan Ding ◽  
De Zhang
Keyword(s):  
North China ◽  
Pattern Mining ◽  
Space Time ◽  
Central China ◽  
Spatiotemporal Pattern ◽  
Severe Drought ◽  
Monthly Precipitation ◽  
Hotspot Analysis ◽  
The Past ◽  
Significant Difference

AbstractDrought is a common natural disaster that greatly affects the crop yield and water supply in China. However, the spatiotemporal characteristics of drought in China are not well understood. This paper explores the spatial and temporal distributions of droughts in China over the past 40 years using multiscale standardized precipitation evapotranspiration index (SPEI) values calculated by monthly precipitation and temperature data from 612 meteorological stations in China from 1980 to 2019 and combines the space-time cube (STC), Mann-Kendall (M-K) test, emerging spatiotemporal hotspot analysis, spatiotemporal clustering and local outliers for the analysis. The results were as follows: 1) the drought frequency and STC show that there is a significant difference in the spatiotemporal distribution of drought in China, with the most severe drought in Northwest China, followed by the western part of Southwest China and the northern part of North China. 2) The emerging spatiotemporal hotspot analysis of SPEI6 over the past 40 years reveals two cold spots in subregion 4, indicating that future droughts in the region will be more severe. 3) A local outlier analysis of the multiscale SPEI yields a low-low outlier in western North China, indicating relatively more severe year-round drought in this area than in other areas. The low-high outlier in central China indicates that this region was not dry in the past and that drought will become more severe in this region in the future.

scholarly journals Relationships between the planetary boundary layer height and surface pollutants derived from lidar observations over China

2018 ◽  
Author(s):  
Tianning Su ◽  
Zhanqing Li ◽  
Ralph Kahn
Keyword(s):  
Boundary Layer ◽  
Air Pollution ◽  
Negative Correlation ◽  
North China Plain ◽  
North China ◽  
Planetary Boundary Layer Height ◽  
Layer Height ◽  
Boundary Layer Height ◽  
The North ◽  
The North China Plain

Abstract. The frequent occurrence of severe air pollution episodes in China has raised great concerns with the public and scientific communities. Planetary boundary layer height (PBLH) is a key factor in the vertical mixing and dilution of near-surface pollutants. However, the relationship between PBLH and surface pollutants, especially particulate matter (PM) concentration, across the whole of China, is not yet well understood. We investigate this issue at ~ 1500 surface stations using PBLH derived from space-borne and ground-based lidar, and discuss the influence of topography and meteorological variables on the PBLH-PM relationship. A generally negative correlation is observed between PM and the PBLH, albeit varying greatly in magnitude with location and season. Correlations are much weaker over the highlands than plains regions, which may be associated with lower pollution levels and mountain breezes. The influence of horizontal transport on surface PM is considered as well, manifested as a negative correlation between surface PM and wind speed over the whole nation. Strong wind with clean upwind sources plays a dominant role in removing pollutants, and leads to weak PBLH-PM correlation. A ventilation rate is introduced to jointly consider horizontal and vertical dispersion, which has the largest impact on surface pollutant accumulation over the North China Plain. Aerosol absorption feedbacks also appear to affect the PBLH-PM relationship, as revealed via comparing air pollution in Beijing and Hong Kong. Absorbing aerosols in high concentrations likely contribute to the significant PBLH-PM correlation over the North China Plain (e.g., during winter). As major precursor emissions for secondary aerosols, sulfur dioxide, nitrogen dioxide, and carbon monoxide have similar negative responses to increased PBLH, whereas ozone is positively correlated with PBLH over most regions, which may be caused by heterogeneous reactions and photolysis rates.

scholarly journals Increasing surface ozone concentrations in the background atmosphere of Southern China, 1994–2007

2009 ◽  
Vol 9 (16) ◽  
pp. 6217-6227 ◽  
Author(s):  
T. Wang ◽  
X. L. Wei ◽  
A. J. Ding ◽  
C. N. Poon ◽  
K. S. Lam ◽  
...  
Keyword(s):  
Hong Kong ◽  
South China ◽  
Surface Ozone ◽  
Eastern China ◽  
Rate Of Change ◽  
Urban Site ◽  
Coastal Regions ◽  
Air Masses ◽  
Background Ozone ◽  
Rate Of Increase

Abstract. Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Three methods are used to derive the rate of change in ozone. A linear fit to the 14-year record shows that the ozone concentration increased by 0.58 ppbv/yr, whereas comparing means in years 1994–2000 and 2001–2007 gives an increase of 0.87 ppbv/yr for a 7-year period. The ozone changes in air masses from various source regions are also examined. Using local wind and carbon monoxide (CO) data to filter out local influence, we find that ozone increased by 0.94 ppbv/yr from 1994–2000 to 2001–2007 in air masses from Eastern China, with similar changes in the other two continent-influenced air-mass groups, but no statistically significant change in the marine air. An examination of the nitrogen dioxide (NO2) column obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO2 in China's three fastest developing coastal regions, whereas NO2 in other parts of Asia decreased during the same period, and no obvious trend over the main shipping routes in the South China Sea was indicated. Thus the observed increase in background ozone in Hong Kong is most likely due to the increased emissions of NO2 (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China. The CO data at Hok Tsui showed less definitive changes compared to the satellite NO2 column. The increase in background ozone likely made a strong contribution (81%) to the rate of increase in "total ozone" at an urban site in Hong Kong, suggesting the need to consider distant sources when developing long-term strategies to mitigate local ozone pollution.

scholarly journals Impact of VOCs on the formation of ozone in a central China city during severe pollution periods

2018 ◽  
Author(s):  
Bowei Li ◽  
Steven Sai Hang Ho ◽  
Sunling Gong ◽  
Jingwei Ni ◽  
Huairui Li ◽  
...  
Keyword(s):  
Temporal Variations ◽  
Central China ◽  
Compressed Natural Gas ◽  
Pmf Model ◽  
Sampling Campaign ◽  
Time Period ◽  
Ozone Formation Potential ◽  
Range Transport ◽  
Volatile Organic ◽  
First Time

Abstract. In this work, a five-month sampling campaign was conducted for volatile organic compounds (VOCs) for the first time in Zhengzhou City, Henan province, China, where ozone (O3) pollution has shown an increasing trend in recent years. Fifty-seven VOCs defined by the Photochemical Assessment Monitoring Stations (PAMS) were sampled using canister method. Meanwhile, other O3 precursor gases were monitored online at four different sites between the time period of May–September, 2017. The results indicated that the average mixing ratio of ΣPAMS (31.57 ± 23.35 ppbv) in Zhengzhou was lower than the other megacities in China, while alkyne was in a significantly higher proportion. The abundances, compositions and ratios of PAMS showed strong spatial and temporal variations. Alkenes were the largest contributors to the ozone formation potential (OFP). On clear days, higher O3 levels were often accompanied with high ΣPAMS/NOx ratio at each site, demonstrating that the VOCs were more sensitive during the O3 formation period in Zhengzhou. Furthermore, source apportionmemt was conducted with Positive Matrix Factorization (PMF) model, and it was found that the use of compressed natural gas (CNG), the evaporation of gasoline and the exhaust from vehicles were the important sources for ambient VOCs at all four sites. Besides, the meterological conditions and long-range transport from other surrounding provinces also had an impact on the air quality determined using the cluster analysis. It is worth mentioning that the reduction in VOCs' emissions is necessary to suppress the O3 pollution.

Dikelocephalid trilobites from theEosaukiafauna (Upper Furongian) of the Taebaek Group, Korea

2011 ◽  
Vol 85 (2) ◽  
pp. 279-297 ◽  
Author(s):  
Seung-Bae Lee ◽  
Duck K. Choi
Keyword(s):  
South China ◽  
North China ◽  
Generic Concept ◽  
Upper Cambrian ◽  
Taebaeksan Basin ◽  
Biostratigraphic Correlation ◽  
Lowermost Part ◽  
Taebaek Group

TheEosaukiafauna is proposed for the upper Furongian trilobite assemblage from the interval spanning from the upper part of the Hwajeol Formation to the lowermost part of the Dongjeom Formation in the Taebaek Group, Taebaeksan Basin, Korea. It is characterized by the dominance of dikelocephalid trilobites comprisingEosaukia micropora, E. bella, E. acuta, Mictosaukiacf.M. globosa, andTaebaeksaukia spinatan. gen. n. sp. Taxonomic reappraisal of the genusMictosaukiathat has been employed as an upper Cambrian index taxon in eastern Gondwana reveals that more than half of the species ofMictosaukiabelong inEosaukia.This study clarifies the generic concept ofEosaukia, which provides a more reliable biostratigraphic correlation for the upper Furongian strata in eastern Gondwanan regions. TheEosaukiafauna is correlated with the“Mictosaukia”faunas from the upper Fengshanian of North China, upper Taoyuanian of South China, and upper Payntonian of Australia.

scholarly journals Virtual versus real water transfers within China

2005 ◽  
Vol 361 (1469) ◽  
pp. 835-842 ◽  
Author(s):  
Jing Ma ◽  
Arjen Y Hoekstra ◽  
Hao Wang ◽  
Ashok K Chapagain ◽  
Dangxian Wang
Keyword(s):  
South China ◽  
Water Scarcity ◽  
North China ◽  
Virtual Water ◽  
Water Transfer ◽  
Qualitative Description ◽  
The North ◽  
Food Deficit ◽  
Virtual Water Flow ◽  
North Water

North China faces severe water scarcity—more than 40% of the annual renewable water resources are abstracted for human use. Nevertheless, nearly 10% of the water used in agriculture is employed in producing food exported to south China. To compensate for this ‘virtual water flow’ and to reduce water scarcity in the north, the huge south–north Water Transfer Project is currently being implemented. This paradox—the transfer of huge volumes of water from the water-rich south to the water-poor north versus transfer of substantial volumes of food from the food-sufficient north to the food-deficit south—is receiving increased attention, but the research in this field has not yet reached further than rough estimation and qualitative description. The aim of this paper is to review and quantify the volumes of virtual water flows between the regions in China and to put them in the context of water availability per region. The analysis shows that north China annually exports about 52 billion m 3 of water in virtual form to south China, which is more than the maximum proposed water transfer volume along the three routes of the Water Transfer Project from south to north.

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