In order to control the spread of the COVID-19 pandemic, the prevention and control measures of public health emergencies were initiated in all provinces of China in early 2020, which had a certain impact on air quality. In this study, taking Jiangsu Province in China as an example, the air pollution levels in different regions under different levels of pandemic prevention and control (PPC) measures are evaluated. The implementation of the prevention and control policies of COVID-19 pandemic directly affected the concentration of air pollutants. No matter what level of PPC measures was implemented, the air quality index (AQI) and pollutant concentrations of NO2, CO, PM10 and PM2.5 were all reduced by varied degrees. The higher the level of PPC measures, the greater the reduction was in air pollutant concentrations. Specifically, NO2 was the most sensitive to PPC policies. The concentrations of CO and atmospheric particulate matter (PM10 and PM2.5) decreased most obviously under the first and second level of PPC. The response speed of air quality to different levels of PPC measures varied greatly among different cities. Southern Jiangsu, which has a higher level of economic development and is dominated by secondary and tertiary industries, had a faster response speed and a stronger responsiveness. The results of this study reflect the economic vitality of different cities in economically advanced regions (i.e., Jiangsu Province) in China. Furthermore, the results can provide references for the formulation of PPC policies and help the government make more scientific and reasonable strategies for air pollution prevention and control.
Compared with individual extreme events, compound events have more severe impacts on humans and the natural environment. This study explores the change in severity of compound extreme high temperature and drought/rain events (CHTDE/CHTRE) and associated influencing factors. The CHTDE and CHTRE intensified in most areas of China in summer (June–July August) during 1961–2014. Under global warming, the increased water-holding capacity of the atmosphere and the decreased relative humidity led to an increase in the severity of CHTDE. The severity of CHTRE is increased because of enhanced transient water vapor convergence and convective motion. Anthropogenic climate change, especially greenhouse gas forcing, which contributes 90% to the linear change in the severity of CHTDE and CHTRE, is identified as the dominant factor affecting the severity of CHTDE in China. In addition, the historical natural forcing (hist-NAT) may be related to the interannual-to-decadal variability in the severity of CHTDE/CHTRE.
<p>Extreme events seriously affect human health&#160;and natural environment. In the present study, several indexes that can describe the severity of compound extreme high temperature and drought/rainy events&#160;(CHTDE/CHTRE) are constructed based on copulas. According to&#160;observations,&#160;CHTDE&#160;and CHTRE&#160;have intensified in most areas of China during 1961&#8211;2014.&#160;The significant increase trend in the severity of CHTDE&#160;and CHTRE is&#160;basically consistent with simulations under historical anthropogenic forcing. This result proves that changes in&#160;CHTDE can be largely attributed to anthropogenic climate change. The historical greenhouse gas forcing is identified to be the dominant factor that affects the severity of CHTDE in China, particularly&#160;in the Tibetan Plateau&#160;and Northwest China. Moreover, the contribution of anthropogenic forcing&#160;to&#160;the linear change of&#160;the CHTRE&#160;severity in China is more than 90%.&#160;In addition, the&#160;ozone&#160;and&#160;land use&#160;signals also&#160;can be detected on change of CHTDE and CHTRE.</p>
Extreme events seriously affect human health and natural environment. In the present study, several indexes that can describe the severity of compound extreme high temperature and drought/rainy events (CHTDE/CHTRE) are constructed based on copulas. According to observations, CHTDE and CHTRE have intensified in most areas of China during 1961–2014. The significant increase trend in the severity of CHTDE and CHTRE is basically consistent with simulations under historical anthropogenic forcing. This result proves that changes in CHTDE can be largely attributed to anthropogenic climate change. The historical greenhouse gas forcing is identified to be the dominant factor that affects the severity of CHTDE in China, particularly in the Tibetan Plateau and Northwest China. Moreover, the contribution of anthropogenic forcing to the linear change of the CHTRE severity in China is more than 90%. In addition, the ozone and land use signals also can be detected on change of CHTDE and CHTRE.
One of main missions for chemistry is to find facile and effective synthetic routes to advanced nanomaterials. A principle feature in this study lays first in the utilization of titanium powder as Ti resource to fabricate onedimensional (1D) pure TiO
<p>In the context of global warming, droughts&#160;occur more frequently&#160;and have caused great losses&#160;to human society.&#160;Therefore, understanding the potential changes in future droughts under climate change is of great scientific importance. In this paper, combining with climate models from CMIP6, the emergent constraint and the Model Goodness Index (MGI)&#160;are used to analyze the characteristics of meteorological, agricultural and hydrological droughts&#160;in China under four socioeconomic scenarios in the mid- and late 21st century. The results show that in the mid-21st century, there will be more frequent meteorological, agricultural and hydrological droughts&#160;in northern China. In the late 21st century, longer and more intense droughts&#160;are more likely to occur in China than in the mid-21st century.&#160;This indicates that drought events in China will gradually become more continuous and serious from the middle to the late 21st century.&#160;Additionally, northwestern&#160;and central China will be the main areas where the three types of drought&#160;areas&#160;and extreme droughts&#160;will increase in the future.&#160;In the mid-21st century, a higher socioeconomic scenario will suppress drought, which will enhance drought conversely in the late 21st century.&#160;These findings are of great significance for drought monitoring under climate change and&#160;can provide a basis for making a drought response&#160;plan.</p>
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