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DehazeNet: An End-to-End System for Single Image Haze Removal Open
Single image haze removal is a challenging ill-posed problem. Existing methods use various constraints/priors to get plausible dehazing solutions. The key to achieve haze removal is to estimate a medium transmission map for an input hazy i…
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A Fast Single Image Haze Removal Algorithm Using Color Attenuation Prior Open
Single image haze removal has been a challenging problem due to its ill-posed nature. In this paper, we propose a simple but powerful color attenuation prior for haze removal from a single input hazy image. By creating a linear model for m…
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Persistent sulfate formation from London Fog to Chinese haze Open
Significance Exceedingly high levels of fine particulate matter (PM) occur frequently in China, but the mechanism of severe haze formation remains unclear. From atmospheric measurements in two Chinese megacities and laboratory experiments,…
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FFA-Net: Feature Fusion Attention Network for Single Image Dehazing Open
In this paper, we propose an end-to-end feature fusion at-tention network (FFA-Net) to directly restore the haze-free image. The FFA-Net architecture consists of three key components:1) A novel Feature Attention (FA) module combines Channe…
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Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China Open
Multiphase chemistry of NO 2 and alkaline matter in aerosol water explains rapid sulfate formation and severe haze in China.
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Severe haze in northern China: A synergy of anthropogenic emissions and atmospheric processes Open
Significance Severe haze events with large temporal/spatial coverages have occurred frequently in wintertime northern China. These extremes result from a complex interplay between emissions and atmospheric processes and provide a unique sc…
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Exploring the severe winter haze in Beijing: the impact of synoptic weather, regional transport and heterogeneous reactions Open
Extreme haze episodes repeatedly shrouded Beijing during the winter of 2012–2013, causing major environmental and health problems. To better understand these extreme events, we performed a model-assisted analysis of the hourly observation …
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Transparent air filter for high-efficiency PM2.5 capture Open
Particulate matter (PM) pollution has raised serious concerns for public health. Although outdoor individual protection could be achieved by facial masks, indoor air usually relies on expensive and energy-intensive air-filtering devices. H…
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Unexpected air pollution with marked emission reductions during the COVID-19 outbreak in China Open
Air pollution epidemic The lockdown enforced in most cities in China in response to the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulted in the virtual absence of motor vehicle traffic and sharply reduced m…
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Enhanced haze pollution by black carbon in megacities in China Open
Aerosol‐planetary boundary layer (PBL) interactions have been found to enhance air pollution in megacities in China. We show that black carbon (BC) aerosols play the key role in modifying the PBL meteorology and hence enhancing the haze po…
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Enhanced secondary pollution offset reduction of primary emissions during COVID-19 lockdown in China Open
To control the spread of the 2019 novel coronavirus (COVID-19), China imposed nationwide restrictions on the movement of its population (lockdown) after the Chinese New Year of 2020, leading to large reductions in economic activities and a…
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Heterogeneous chemistry: a mechanism missing in current models to explain secondary inorganic aerosol formation during the January 2013 haze episode in North China Open
Severe regional haze pollution events occurred in eastern and central China in January 2013, which had adverse effects on the environment and public health. Extremely high levels of particulate matter with aerodynamic diameter of 2.5 μm or…
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Ammonia emission control in China would mitigate haze pollution and nitrogen deposition, but worsen acid rain Open
Significance Atmospheric ammonia plays important roles in fine particle pollution, acid rain, and nitrogen deposition. China, known as the world’s top emitter of gaseous ammonia, plans to control ammonia emissions to mitigate the haze poll…
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New insights into PM <sub>2.5</sub> chemical composition and sources in two major cities in China during extreme haze events using aerosol mass spectrometry Open
During winter 2013–2014 aerosol mass spectrometer (AMS) measurements were conducted for the first time with a novel PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 µm) lens in two major cities of China: Xi'an and Beijing. We deno…
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Ozone pollution in the North China Plain spreading into the late-winter haze season Open
Significance The North China Plain experiences severe summer ozone pollution, but ozone during winter haze (particulate) pollution events has been very low. Here, we show that the abrupt decrease in nitrogen oxide (NO x ) emissions followi…
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Public health impacts of the severe haze in Equatorial Asia in September–October 2015: demonstration of a new framework for informing fire management strategies to reduce downwind smoke exposure Open
In September–October 2015, El Niño and positive Indian Ocean Dipole conditions set the stage for massive fires in Sumatra and Kalimantan (Indonesian Borneo), leading to persistently hazardous levels of smoke pollution across much of Equato…
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An overview of the first decade of Polly <sup>NET</sup> : an emerging network of automated Raman-polarization lidars for continuous aerosol profiling Open
A global vertically resolved aerosol data set covering more than 10 years of observations at more than 20 measurement sites distributed from 63° N to 52° S and 72° W to 124° E has been achieved within the Raman and polarization lidar netwo…
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D-HAZY: A dataset to evaluate quantitatively dehazing algorithms Open
Dehazing is an image enhancing technique that emerged in the recent years. Despite of its importance there is no dataset to quantitatively evaluate such techniques. In this paper we introduce a dataset that contains 1400+ pairs of images w…
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Haze Days in North China and the associated atmospheric circulations based on daily visibility data from 1960 to 2012 Open
Haze is a severe hazard that greatly influences traffic and daily life with great economic losses and threats to human health. To enhance understanding of the haze occurrences, this study examined the haze variations over North China and t…
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Sulfate formation is dominated by manganese-catalyzed oxidation of SO2 on aerosol surfaces during haze events Open
The formation mechanism of aerosol sulfate during wintertime haze events in China is still largely unknown. As companions, SO 2 and transition metals are mainly emitted from coal combustion. Here, we argue that the transition metal-catalyz…
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Impact of Aerosol‐PBL Interaction on Haze Pollution: Multiyear Observational Evidences in North China Open
Atmospheric aerosols have been found to influence the development of planetary boundary layer (PBL) and hence to enhance haze pollution in megacities. Previous works on aerosol‐PBL interaction were mainly based on model simulation for shor…
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Fine-particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models Open
pH is an important property of aerosol particles but is difficult to measure directly. Several studies have estimated the pH values for fine particles in northern China winter haze using thermodynamic models (i.e., E-AIM and ISORROPIA) and…
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Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015 Open
We investigate the rapid formation and evolutionary mechanisms of an extremely severe and persistent haze episode that occurred in northern China during winter 2015 using comprehensive ground and vertical measurements, along with receptor …
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Changes in Aerosol Chemistry From 2014 to 2016 in Winter in Beijing: Insights From High‐Resolution Aerosol Mass Spectrometry Open
Air quality has been continuously improved in recent years in Beijing, yet severe haze episodes still frequently occur in winter. Here we deployed an Aerodyne high‐resolution aerosol mass spectrometer in two winter seasons during the same …
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Wintertime aerosol chemistry and haze evolution in an extremely polluted city of the North China Plain: significant contribution from coal and biomass combustion Open
The North China Plain (NCP) frequently experiences heavy haze pollution, particularly during wintertime. In winter 2015–2016, the NCP region suffered several extremely severe haze episodes with air pollution red alerts issued in many citie…
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Aqueous production of secondary organic aerosol from fossil-fuel emissions in winter Beijing haze Open
Significance Secondary organic aerosol (SOA) from fossil-fuel combustion is a major component of Beijing winter haze pollution but its formation mechanisms are unclear. It is generally assumed to originate from atmospheric oxidation of vol…
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Fast oxidation of sulfur dioxide by hydrogen peroxide in deliquesced aerosol particles Open
Significance Atmospheric sulfate aerosol particles contribute significantly to poor air quality and direct forcing of the Earth’s climate. However, air pollution and climate models simulate the formation of sulfate using acid rain chemistr…
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Increase in winter haze over eastern China in recent decades: Roles of variations in meteorological parameters and anthropogenic emissions Open
The increase in winter haze over eastern China in recent decades due to variations in meteorological parameters and anthropogenic emissions was quantified using observed atmospheric visibility from the National Climatic Data Center Global …
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Modeling study of the 2010 regional haze event in the North China Plain Open
The online coupled Weather Research and Forecasting-Chemistry (WRF-Chem) model was applied to simulate a haze event that happened in January 2010 in the North China Plain (NCP), and was validated against various types of measurements. The …
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Free Space Optics: Current Applications and Future Challenges Open
FSO is a communication system where free space acts as medium between transceivers and they should be in LOS for successful transmission of optical signal. Medium can be air, outer space, or vacuum. This system can be used for communicatio…