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Chen L, Zhang F, Ren J, Li Z, Xu W, Sun Y, Liu L, Wang X. Changes in wintertime visibility across China over 2013-2019 and the drivers: A comprehensive assessment using machine learning method. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 912:169516. [PMID: 38135088 DOI: 10.1016/j.scitotenv.2023.169516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/05/2023] [Accepted: 12/17/2023] [Indexed: 12/24/2023]
Abstract
Effective emission reduction measures have largely lowered the particulate concentration in China, but low-visibility events still occur frequently, greatly affecting people's daily life, travel, and health. In the context of carbon neutrality strategy and climate change, the mechanisms governing visibility changes may be undergoing a transformation. To address this critical issue, we have undertaken a comprehensive assessment by employing a novel approach that combines site observations, model-derived datasets, and machine learning techniques. Our analysis of the dataset shows varying degrees of improvement in wintertime visibility in regions such as North China, South China, and the Fenwei Plain over 2013-2019, but an unexpected deterioration (approximately 1 km yr-1) in central and southern China (CSC). We further elucidate key roles of PM2.5 reduction in these regions with visibility improvement; whereas the unsatisfactory visibility trend in CSC was caused by combined effect of relative humidity (RH) increase (47 %), aerosol hygroscopicity (κ) enhancement (9 %), and boundary layer (BLH) reduction (8 %), which greatly overwhelms the effect of PM2.5 reduction recently. Moreover, the study reveals a growing influence of RH on the wintertime visibility, reaching 40 % ± 24 % to the total contribution in 2019, while that of PM2.5 declined to 18 % ± 19 % and is expected to further diminish with emission reduction. Note those often-neglected factors-temperature, wind speed, BLH, and κ, account for over 40 % of the total contribution. Though the importance of aerosol hygroscopic growth to visibility was found decreasing recently, it retains non-negligible impacts on driving inter-annual visibility trends. This study yields innovative insights for air pollution control, underscoring the imperative of region-specific strategies to mitigate low-visibility events.
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Affiliation(s)
- Lu Chen
- Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China; School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), 518055 Shenzhen, China
| | - Fang Zhang
- School of Civil and Environmental Engineering, Harbin Institute of Technology (Shenzhen), 518055 Shenzhen, China.
| | - Jingye Ren
- Xi'an Institute for Innovative Earth Environment Research, Xi'an 710061, China
| | - Zhigang Li
- Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
| | - Weiqi Xu
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Yele Sun
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
| | - Lingling Liu
- College of Environment and Science, Beijing Normal University, Beijing 100875, China
| | - Xinming Wang
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
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Miloshevsky A, Wilson BA, Williams BP, Hooper DA, Grice WP, Peters NA. Space-based quantum networking in the presence of a nuclear disturbed environment. APPLIED OPTICS 2023; 62:G60-G68. [PMID: 37707064 DOI: 10.1364/ao.486818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 04/11/2023] [Indexed: 09/15/2023]
Abstract
Space-based quantum networks provide a means for near-term long-distance transmission of quantum information. This article analyzed the performance of a downlink quantum network between a low-Earth-orbit satellite and an observatory operating in less-than-ideal atmospheric conditions. The effects from fog, haze, and a nuclear disturbed environment on the long-range distribution of quantum states were investigated. A density matrix that estimates the quantum state by capturing the effects from increased signal loss and elevated background noise to estimate the state fidelity of the transmitted quantum state was developed. It was found that the nuclear disturbed environment and other atmospheric effects have a degrading effect on the quantum state. These environments impede the ability to perform quantum communications for the duration of the effects. In the case of the nuclear disturbed environment, the nuclear effects subside quickly, and network performance should return to normal by the next satellite pass.
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Sun X, Zhao T, Tang G, Bai Y, Kong S, Zhou Y, Hu J, Tan C, Shu Z, Xu J, Ma X. Vertical changes of PM 2.5 driven by meteorology in the atmospheric boundary layer during a heavy air pollution event in central China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 858:159830. [PMID: 36343804 DOI: 10.1016/j.scitotenv.2022.159830] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 08/28/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Regional PM2.5 transport is a crucial factor affecting air quality, and the meteorological mechanism in the atmospheric boundary layer (ABL) has not been fully understood over the receptor region in the regional transport of air pollutants. Based on the intensive vertical measurements of air pollutants and meteorology in the ABL during a transport-induced heavy air pollution event in Xiangyang, an urban site over a receptor region in central China, we investigated the meteorological mechanism in vertical PM2.5 changes in the ABL for heavy air pollution over the receptor region. Driven by northerly winds, regional PM2.5 transport was built from upstream northern China to downstream central China, where the observed ABL structures were unstable throughout the air pollution event. We assessed the ABL structures with meteorological and PM2.5 profiles at growth, maintenance, and dissipation stages, and elucidated the mechanism of regional PM2.5 transport inducing air pollution over the receptor region with the contribution of thermal and mechanical factors. The regional PM2.5 transport was concentrated in the upper ABL over the downwind receptor region with high PM2.5 concentrations at altitudes of 600-800 m, where the transported PM2.5 peaks were downwards mixed by vertical wind shear, forming the vertical PM2.5 transport from the upper ABL to near-surface in the growth stage; the weakened winds and less unstable structures in the ABL favored the sustained pollution with slight vertical PM2.5 changes in the maintenance stage, which was dominated by thermal factors with 87 % contribution; the removal of PM2.5 was triggered by increasing winds from the upper ABL, activating the dissipation of heavy PM2.5 pollution with the mechanical effect accounting for 60 % in the dissipation stage. These findings could improve our understanding of ABL's influence on air pollution over the receptor region with implications for the regional transport of air pollutants in environmental changes.
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Affiliation(s)
- Xiaoyun Sun
- Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, PREMIC, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Tianliang Zhao
- Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, PREMIC, Nanjing University of Information Science and Technology, Nanjing 210044, China.
| | - Guiqian Tang
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
| | - Yongqing Bai
- Institute of Heavy Rain, China Meteorological Administration, Wuhan 430205, China
| | - Shaofei Kong
- Department of Atmospheric Sciences, School of Environmental Studies, China University of Geosciences (Wuhan), Wuhan 430074, China
| | - Yue Zhou
- Institute of Heavy Rain, China Meteorological Administration, Wuhan 430205, China
| | - Jun Hu
- Fujian Academy of Environmental Sciences, Fuzhou 350011, China
| | - Chenghao Tan
- State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuozhi Shu
- Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, PREMIC, Nanjing University of Information Science and Technology, Nanjing 210044, China
| | - Jiaping Xu
- Jiangsu Climate Center, Nanjing 210009, China
| | - Xiaodan Ma
- Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, PREMIC, Nanjing University of Information Science and Technology, Nanjing 210044, China
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Development of Two-Dimensional Visibility Estimation Model Using Machine Learning: Preliminary Results for South Korea. ATMOSPHERE 2022. [DOI: 10.3390/atmos13081233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A two-dimensional visibility estimation model was developed, based on random forest (RF), a machine learning-based technique. A geostatistical method was introduced into the visibility estimation model for the first time to interpolate point measurement data to gridded data spatially with a pixel size of 10 km. The RF-based model was trained using gridded visibility data, as well as meteorological and air pollution input variable data, for each location in South Korea, which were characterized by complex geographical features and high air pollution levels. Generally, relative humidity was the most important input variable for the visibility estimation (average mean decrease accuracy: 35%). However, PM2.5 tended to be the most crucial variable in polluted regions. The spatial interpolation was found to result in an additional visibility estimation error of 500 m in locations where no adjacent visibility observations within 0.2° were available. The performance of the proposed model was preliminarily assessed. Generally, the best detection performance was achieved in good visibility conditions (visibility range: 10 to 20 km). This study is the first to demonstrate a visibility estimation model based on a geostatistical method and machine learning, which can provide visibility information in locations for which no observations exist.
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Ting YC, Young LH, Lin TH, Tsay SC, Chang KE, Hsiao TC. Quantifying the impacts of PM 2.5 constituents and relative humidity on visibility impairment in a suburban area of eastern Asia using long-term in-situ measurements. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 818:151759. [PMID: 34822889 DOI: 10.1016/j.scitotenv.2021.151759] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 10/08/2021] [Accepted: 11/13/2021] [Indexed: 06/13/2023]
Abstract
The deterioration of visibility due to air pollutants and relative humidity has been a serious environmental problem in eastern Asia. In most previous studies, chemical compositions of atmospheric particles were provided using filter-based offline analyses, which were unable to provide long-term and in-situ measurements that resolve sufficient temporal variations of air pollution and meteorology, hindering the resolution of the relationship between air quality and visibility. Here, we present a year-long continuously measured data from a comprehensive suite of online instruments to investigate diurnal and seasonal impacts of the aerosol chemical compositions in PM2.5 on visibility seasonally and diurnally. The measured dry aerosol extinction at λ = 550 nm reached a closure with that predicted by aerosol compositions within 12%. However, the hygroscopic growth of particles under ambient RH could enhance the aerosol extinction by a factor of 2-6, matching the perceptive visibility of the public. Particulate ammonium nitrate was most sensitive to reducing visibility, while ammonium sulfate contributed the most to the light extinction. In spring and winter, the monsoon and stagnant air masses reduced the visibility and increased PM2.5 (>35 μg m-3). The moisture was found to substantially enhance the light extinction under RH = 60-90%, reducing visibility by approximately 15 km, largely attributed to hygroscopic inorganic salts. This study serves as a metric to highlight the need to consider the influence of RH, and aqueous reactions in producing secondary inorganic aerosols on atmospheric visibility, underpinning the more accurate mitigation strategies of air pollution.
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Affiliation(s)
- Yu-Chieh Ting
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan
| | - Li-Hao Young
- Department of Occupational Safety and Health, China Medical University, Taichung, Taiwan
| | - Tang-Huang Lin
- Center for Space and Remote Sensing Research, National Central University, Taoyuan, Taiwan
| | - Si-Chee Tsay
- NASA Goddard Space Flight Centre, Greenbelt, MD, USA
| | - Kuo-En Chang
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan; Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
| | - Ta-Chih Hsiao
- Graduate Institute of Environmental Engineering, National Taiwan University, Taipei, Taiwan; Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan.
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A Study on the Long-Term Variations in Mass Extinction Efficiency Using Visibility Data in South Korea. REMOTE SENSING 2022. [DOI: 10.3390/rs14071592] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Fine particulate matter (PM) release is regulated by environmental policies in most countries. This study investigated long–term trends in the mass extinction efficiency (Qe) of aerosols in Northeast Asia. For this purpose, the Qe was calculated using visibility, PM2.5 recorded between 2015 and 2020, and PM10 recorded between 2001 and 2020 at eight Korean sites. The Qe of PM10 (Qe,10) showed an increasing trend with 0.06~0.22 (m2/g)/yr in seven cities except for Jeju. The Qe of PM2.5 (Qe,2.5) also showed an increasing trend with 0.28–2.47 (m2/g)/yr in all cities. In this study, PM10 and PM2.5, were divided into low, moderate, and high concentrations, and the Qe value change by year was examined. Qe,10 showed a tendency to decrease at low concentrations (19–21 μg/m3). However, at moderate (69–71 μg/m3) and high concentrations (139–141 μg/m3), Qe,10 increased in most regions. Qe,2.5 showed an increasing trend at low concentration (9–11 μg/m3), moderate concentration (29–31 μg/m3), and high concentration (69–71 μg/m3), except for Suwon and Pohang, where data were insufficient for analysis. Both Qe,10 and Qe,2.5 showed an increasing trend. The increase in Qe indicated that the visibility-impairing effect of PM can increase even if the same concentration of PM is present. The visibility-impairing effects of PM vary based on the composition, size and other characteristics of the particles in the atmosphere at a given point in time and not simply the quantity of particles. This means that reducing the quantity of particles does not reliably produce a proportionate improvement in visibility. Air quality policies must take the variable nature of PM particles and their effect on visibility into account so that more consistent improvements in air quality can be achieved.
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Liu N, Luo T, Han Y, Yang K, Zhang K, Wu Y, Weng N, Li X. Analysis of the atmospheric visibility influencing factors under sea-land breeze circulation. OPTICS EXPRESS 2022; 30:7356-7371. [PMID: 35299500 DOI: 10.1364/oe.447141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 01/27/2022] [Indexed: 06/14/2023]
Abstract
Factors influencing atmospheric visibility (VIS) in coastal areas are more complex than those for inland and far oceans owing to the complex circulation and aerosol sources. This study analyzed the factors influencing VIS under sea-land breeze circulation (SLBC) for different external aerosol sources based on field survey data in southern Chinese coastal areas. First, SLBC characteristics observed during the experiment period showed that on SLBC days, sea breeze occurs more frequently (∼50%) than land breeze (∼27%), and the wind speed (WS) is generally small, with a mean sea and land breeze WSs of ∼2.18 m/s and ∼2.38 m/s, respectively. Then, analysis of factors influencing VIS was conducted for different land/sea breeze conditions and external aerosol source conditions indicated by the HYSPLIT4 model simulations. Results showed that the aerosol particle number concentration (PNC) and relative humidity (RH) both had negative correlations with VIS, while only very weak relationships between WS and VIS were found, possibly due to small WSs on SLBC days or because local aerosols were not pure marine aerosols. Further two-factor analysis of VIS showed that the power-law function relating VIS with PNC in each RH bin ranges from ∼-0.3 to ∼-1.5, and VIS exhibited sharper exponential decline with increasing PNC under high RH. A new method of retrieving aerosol-extinction hygroscopic growth factor (fext) with the measured VIS, RH, and PNC was developed to investigate the optical hygroscopic growth property of aerosols. Results show that aerosols in the study area have similar fext under different land/sea breeze and external aerosol source conditions; the deliquescence RH of aerosols is ∼60%, suggesting that mainly polluted marine aerosol was observed during experiments in this area.
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Hooper DA, Wilson BA, Miloshevsky A, Williams BP, Peters NA. Effects of a nuclear disturbed environment on a quantum free space optical link. OPTICS EXPRESS 2021; 29:27254-27277. [PMID: 34615145 DOI: 10.1364/oe.433223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
This manuscript investigates the potential effect of a nuclear-disturbed atmospheric environment on the signal attenuation of a ground/satellite transmitter/receiver system for both classical optical and quantum communications applications. Attenuation of a signal transmitted through the rising nuclear cloud and the subsequently transported debris is modeled climatologically for surface-level detonations of 10 kt, 100 kt, and 1 Mt. Attenuation statistics were collected as a function of time after detonation. These loss terms were compared to normal loss sources such as clouds, smoke from fires, and clear sky operation. Finally, the loss was related to the degradation of transmitted entanglement derived from Bayesian mean estimation.
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Integrated Mobile Laboratory for Air Pollution Assessment: Literature Review and cc-TrAIRer Design. ATMOSPHERE 2021. [DOI: 10.3390/atmos12081004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
To promote research studies on air pollution and climate change, the mobile laboratory cc-TrAIRer (Climate Change—TRailer for AIR and Environmental Research) was designed and built. It consists of a trailer which affords particles, gas, meteorological and noise measurements. Thanks to its structure and its versatility, it can easily conduct field campaigns in remote areas. The literature review presented in this paper shows the main characteristics of the existing mobile laboratories. The cc-TrAIRer was built by evaluating technical aspects, instrumentations and auxiliary systems that emerged from previous studies in the literature. Some of the studies conducted in heterogeneous topography areas, such as the Po Valley and the Alps, using instruments that were chosen to be located on the mobile laboratory are here reported. The preliminary results highlight the future applications of the trailer and the importance of high temporal resolution data acquisition for the characterization of pollution phenomena. The potential applications of the cc-TrAIRer concern different fields, such as complex terrain, emergency situations, worksite and local source impacts and temporal and spatial distributions of atmospheric compounds. The integrated use of gas and particle analysers, a weather station and environment monitoring systems in a single easily transportable vehicle will contribute to research studies on global aspects of climate change.
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