Suchergebnisse

Fires have attracted interest and generated alarm since the early 1980s. This concern has been particularly evident in tropical forests of Southeast Asia and the Amazon, but disastrous fires in recent summers in Australia, Europe, and the United States have drawn worldwide attention. Concern about forest fires, and related air pollution and biodiversity impacts, led international organisations and northern countries - such as the Asian Development Bank, the European Union, the Food and Agriculture Organisation, the United Nations Environment Programme, the World Bank, and the government of Germany - to undertake fire assessments and provide technical assistance. Nongovernmental organisations, such as the International Union for Conservation of Nature and Natural Resources and World Wide Fund for Nature, have also devoted increased attention to fires. Aiming at prevention of future fires, 40 fire projects and missions costing well over US$30 million have worked in Indonesia over the last 20 years. Despite the money and effort spent on them, fires continue to burn every year. It may appear to some that efforts to address the 'fire problem' have not been effective as fires still occur. There remains a lack of clarity about 'fire problems', which has, at times, led to the adoption of policies that may have negative impacts on livelihoods, the environment, and the economy. Two 'simple' changes in the way fires are considered would significantly improve fire-related policies and initiatives. • Fires should be seen as a component of land management processes, rather than as a 'problem' to be prevented, suppressed, or mitigated. • Not all fires are the same. These two points are discussed in the context of Southeast Asia, and particularly Indonesia, as an example of the problems and questions faced by tropical countries. We argue that efforts on fires so far have generated increased knowledge of the 'fire problem'; now, we need to capitalize on that knowledge to avoid wasting money in the future.

Fires including peatland burning in Southeast Asia have become a major concern to the general public as well as governments in the region. This is because aerosols emitted from such fires can cause persistent haze events under certain weather conditions in downwind locations, degrading visibility and causing human health issues. In order to improve our understanding of the spatiotemporal coverage and influence of biomass burning aerosols in Southeast Asia, we have used surface visibility and particulate matter concentration observations, supplemented by decade-long (2003 to 2014) simulations using the Weather Research and Forecasting (WRF) model with a fire aerosol module, driven by high-resolution biomass burning emission inventories. We find that in the past decade, fire aerosols are responsible for nearly all events with very low visibility (< 7 km). Fire aerosols alone are also responsible for a substantial fraction of low-visibility events (visibility < 10 km) in the major metropolitan areas of Southeast Asia: up to 39 % in Bangkok, 36 % in Kuala Lumpur, and 34 % in Singapore. Biomass burning in mainland Southeast Asia accounts for the largest contribution to total fire-produced PM[subscript 2.5] in Bangkok (99 %), while biomass burning in Sumatra is a major contributor to fire-produced PM[subscript 2.5] in Kuala Lumpur (50 %) and Singapore (41 %). To examine the general situation across the region, we have further defined and derived a new integrated metric for 50 cities of the Association of Southeast Asian Nations (ASEAN): the haze exposure day (HED), which measures the annual exposure days of these cities to low visibility (< 10 km) caused by particulate matter pollution. It is shown that HEDs have increased steadily in the past decade across cities with both high and low populations. Fire events alone are found to be responsible for up to about half of the total HEDs. Our results suggest that in order to improve the overall air quality in Southeast Asia, mitigation policies targeting both biomass burning and fossil fuel burning sources need to be implemented. ; Singapore-MIT Alliance for Research and Technology Center ; National Science Foundation (U.S.) (AGS-1339264) ; United States. Department of Energy (DE-FG02-94ER61937) ; United States. Environmental Protection Agency (XA-83600001-1)

This article will answer the question why Indonesia is not yet fullyoptimized in solving forest fires. The types of literature is qualitative analysis techniques with collecting secondary data (library research). In result that the forest fires in Indonesia is because inability of the government to preserve forest, or other terms are neglected phenomenon. It still repeated every year with 20 trillion losses in 2015 with total land area about 2.1 million hectares. This condition is equal to four timesBali island and 32 times the size of Jakarta. Analysis process that still recurrence of catastrophic forest fires, as the result by not optimal factors: a) governance management of the disaster, b) Not optimal in disaster as an instrument of diplomacy, it relates to how Indonesia influence a number of countries to help tackle the fire, c) the consequences and legal compliance related to transboundary haze. Smoke pollution control is not legally ratified by Indonesia, posed no legalconsequences for Indonesia. Contrary to the Geneva Convention, the Riodeclaration and the declaration Stockholm advocated that the country should maintain its natural and conformity with nature, so it does not interfere with the activities of other countries. Keyword: Disaster, Diplomacy, Compliance Theory, Rational Choice

Cover -- Half-title -- Title page -- Copyright information -- Dedication -- Table of contents -- Acknowledgements -- List of acronyms -- 1 Personal Beginnings -- Part I The Changing Arctic -- 2 The Arctic Messenger -- Part II Working Together -- 3 The Arctic Messenger Gains a Voice: The Arctic Monitoring and Assessment Programme -- Part III What Is the Present State of Knowledge? -- 4 Radioactivity -- Fundamentals -- A Note on Units of Measurement and Concepts of Radiation Dose -- Arctic Monitoring and Assessment Programme (AMAP) Assessments -- Fallout From Atmospheric Testing of Nuclear Weapons, Peaceful Nuclear Explosions and the Chernobyl Accident -- Marine Discharge of Nuclear Wastes From Nuclear Reprocessing Plants at Sellafield in the United Kingdom and at Cap de la Hague in France -- Local Arctic "Hot Spots" and Potential Sources of Radioactive Contamination -- Natural Radioactivity and TENORM -- The Long and the Short of It -- 5 Heroic Efforts -- 6 Acidification and Arctic Haze -- The Long and the Short of It -- 7 Stratospheric Ozone Depletion -- Why Is Stratospheric Ozone Important? -- Ozone-Depleting Substances and the Thinning of the Ozone Layer -- Ozone-Depleting Substances in the Atmosphere Since January 1989 -- Projected Recovery of the Stratospheric Ozone Layer -- The Biological Effects of UV Radiation and Trends in UV Exposure -- The Long and the Short of It -- 8 Persistent Organic Pollutants and Heavy Metals (Including Mercury) -- Early History: Beginning to Understand the Behaviour of POPs and Mercury in the Arctic -- Early History: Stimulating International Action to Control the Entry of POPs and Heavy Metals to the Environment -- The Symbiotic Relationship Between Emerging Science and International Negotiations for Controls on POPs and Heavy Metals -- Uncomfortable Realities, Including the Arctic Dilemma.

This article analyzes the influence of photographs from polycode environmental media texts on the youth audience with the use of eye-tracking. The study is supported by 102 photographs from environmental media texts in online publications and online city communities of the Chelyabinsk and Sverdlovsk regions. The content analysis of the photos reveals the most frequently repeated visual images: emissions / smog / haze; a general panoramic view of the city; industrial enterprises and their emissions; the pollution of forests, parks, and bodies of water; landfills; the negative impact on wildlife; and anthropogenic accidents. The analysis of the influence of the photos on the youth audience (100 people, 18–22 years old) using eye-tracking established the degree of respondents' attention to the images based on the indicators of time until the first fixation on the area of interest (ttf, ms.), total time of viewing the area of interest (fix time, ms.), and the total number of fixations on the area of interest (all fix, units). The results showed that most attention is paid to images of landfills and the negative impact on flora and fauna. Special attention is paid to images of people and animals. The least attention is paid to stock images that are not related to the content of the news text.

Fine particulate matter in the lower atmosphere (PM 2.5 ) continues to be a major public health problem globally. Identifying the key contributors to PM 2.5 pollution is important in monitoring and managing atmospheric quality, for example, in controlling haze. Previous research has been aimed at quantifying the relationship between PM 2.5 values and their underlying factors, but the spatial and temporal dynamics of these factors are not well understood. Based on random forest and Shapley additive explanation (SHAP) algorithms, this study analyses the spatiotemporal variations in selected key factors influencing PM 2.5 in Zhejiang Province, China, for the period 2000–2019. The results indicate that, while factors influencing PM 2.5 varied significantly during the period studied, SHAP values suggest that there is consistency in their relative importance as follows: meteorological factors (e.g., atmospheric pressure) > socioeconomic factors (e.g., gross domestic product, GDP) > topography and land cover factors (e.g., elevation). The contribution of GDP and transportation factors initially increased but has declined in the recent past, indicating that economic and infrastructural development does not necessarily result in increased PM 2.5 concentrations. Vegetation productivity, as indicated by changes in NDVI, is demonstrated to have become more important in improving air quality, and the area of the province over which it constrains PM 2.5 concentrations has increased between 2000 and 2019. Mapping of SHAP values suggests that, although the relative importance of industrial emissions has declined during the period studied, the actual area positively impacted by such emissions has actually increased. Despite developments in government policy, greater efforts to conserve energy and reduce emissions are still needed. The study further demonstrates that the combination of random forest and SHAP methods provides a valuable means to identify regional differences in key factors affecting atmospheric PM 2.5 values and offers a reliable reference for pollution control strategies.

Although climate-linked impacts on ASEAN's economy, increasing vulnerability to severe weather, and interlinkages to transboundary haze, health, security and marine pollution are evident, a recent survey by the ISEAS - Yusof Ishak Institute reveals that Southeast Asians are ambivalent about ASEAN's effectiveness in tackling climate change.All ASEAN Member States (AMS) are fully committed to accelerating reductions to global emissions under the Paris Agreement and demonstrate political will to set up intersectoral climate governance on renewable energy transition, agriculture and food security, forest and land use protection, disaster risk management, conservation on biodiversity, among many other measures.Under the ASEAN Socio-Cultural Community (ASCC) pillar, the ASEAN Ministerial Meetings on the Environment (AMME) and the ASEAN Senior Officials' Meeting on the Environment (ASOEN) meet annually to discuss environment-related issues, including climate change. The ASEAN Working Group on Climate Change (AWGCC), one of seven technical working groups reporting to the ASOEN, is tasked to enhance regional cooperation on climate change, promote collaboration between sectoral bodies, and articulate ASEAN's concerns and priorities at the international level.Climate change issues have become cross-cutting and involve various ASEAN sectoral bodies. The AWGCC's role, however, is still limited to the environmental mandate.ASEAN needs to establish a super coordinating body on climate change that can ensure information sharing across ASEAN bodies, convene support from dialogue partners, and engage with civil society organizations. The ASEAN Coordinating Council Working Group on Public Health Emergencies (ACCWG-PHE) model established during the COVID-19 crisis can serve as a precedent.

Introduction : framing environmental justice studies and movements in Nepal / Jonathan K London, Jagannath Adhikari, and Thomas Robertson -- Towards a new paradigm for environmental justice studies in Nepal / Jonathan K London and Sudikshya Bhandari -- People's movements for environmental justice in Nepal : a historical perspective / Jagannath Adhikari -- Environmental justice and the role of Nepalese judiciary : a missed opportunity / Jony Mainali -- Environmental injustice in confronting gendered access to land in Nepal : joint land ownership as a promising practice / Srijana Baral, Kalpana Karki, and Kanchan Lama -- Environmental justice and unfree agricultural labourers in the Eastern Tarai of Nepal / Suresh Kumar Dhakal -- Connecting Dalit land rights and climate justice / Madan Pariyar and Arjun Biswakama -- Environmental justice and pesticides / Kishor Atreya, Kanchan Kattel, Anisha Sapkota, and Hom Nath Gartaula -- From red to green to grey hills : reflections on the four-decade-long journey of community forestry and environmental justice in Nepal / Sunita Chaudhary -- Protected areas and expendable communities : human-animal conflict survivors and unjust compensation in the Koshi Tappu Wildlife Reserve / Dhirendra Nalbo -- The river people and the parks : political ecology of conservation and indigenous livelihoods in Nepal's Terai / Naya Sharma Paudel, Sudeep Jana Thing, and Rahul Karki -- Disaster is social : uneven effect and recovery from the 2015 Nepal earthquake / Mukta S. Tamang -- Indigenous struggles for development justice in Nepal : environmentalism on the ground / Prabindra Shakya -- Ensuring health, hygiene and dignity for solid waste workers / Prashanna Pradhan and Bhawana Sharma -- Urban environmental justice : for whom, from whom? / Kirti Kusum Joshi -- Cycling for livelihood in Nepal : seeking justice on two wheels / Tara Lal Shrestha and Bidhya Shrestha -- Through the haze : air pollution and environmental justice / Arnico K. Panday and Arti Govinda Shrestha -- Driving towards environmental justice on the streets of Kathmandu / Bhushan Tuladhar -- Building political capabilities through participation for environmental justice in informal housing in Kathmandu / Sangeeta Singh and Bijay Singh -- Climate change in Nepal through an indigenous environmental justice lens / Pasang Yangjee Sherpa -- Women, water and weather : Kavre villages adapt to the increasing impacts of the climate crisis / Sonia Awale -- Applying a climate justice framework to understand inequities in urban water governance amid climate change challenges in Nepal / Gyanu Maskey, Poshendra Satyal, Monica Giri, and Prajal Pradhan -- The stress of poverty in tackling tuberculosis in Nepal / Marissa Taylor -- Impacts of lead contamination on children's health in Nepal / Meghnath Dhimal, Mandira Lamichhane Dhimal, and Madhusudan Subedi.

Chapter 1 Biomass Burning in South/Southeast Asia Needs and Priorities[Krishna Prasad Vadrevu, Toshimasa Ohara,and Christopher Justice]Section I Mapping and Monitoring of Fires,including Burned AreasChapter 2 Identification of Smoldering Peatland Fires in Indonesia viaTriple-Phase Temperature Analysis of VIIRS Nighttime Data[Christopher D. Elvidge, Mikhail Zhizhin, Kimberly Baugh,and Feng-Chi Hsu]Chapter 3 Evaluation of Sentinel-3 SLSTR Data for Mapping Firesin Forests, Peatlands, and Croplands A Case Study overAustralia, Indonesia, and India[Aditya Eaturu and Krishna Prasad Vadrevu]Chapter 4 An Assessment of Burnt Area Signal Variations in Laos UsingSentinel-1A&B Datasets[Krishna Prasad Vadrevu, Aditya Eaturu, Sumalika Biswas,and Chittana Phompila]Chapter 5 Peatland Surface Loss due to Fires in Central Kalimantan,Indonesia A Case Study Using Differential InterferometrySAR (DInSAR)[Yessy Arvelyna, Hidenori Takahashi, Lies Indrayanti,Hiroshi Hayasaka, Krishna Prasad Vadrevu, Retno Maryani,Mitsuru Osaki, and Hirose Kazuyo]Chapter 6 Burnt Area Mapping in Nainital, Uttarakhand, India, UsingVery High-Resolution PlanetScope Imagery[Krishna Prasad Vadrevu, Aditya Eaturu, and Sumalika Biswas]Chapter 7 Investigations on Land and Forest Fires in the North IndianRegion over a Decade[Narendra Singh and Ashish Kumar]Chapter 8 Spatial Point Patterns and Scale Analysis of Vegetation Firesin Laos and Cambodia[Krishna Prasad Vadrevu, Sumalika Biswas, and Aditya Eaturu]Section II Land Use, Forests, and Biomass BurningChapter 9 Vegetation Fire Status and Management in Bhutan[Pankaj Thapa, Krishna Prasad Vadrevu, Aditya Eaturu,and Sumalika Biswas]Chapter 10 Biomass Burning in Malaysia: Sources and Impacts[Justin Sentian, Franky Herman, Vivian Kong Wan Yee,Carolyn Melissa Payus, and Mohd Sharul Mohd Nadzir]Chapter 11 Swidden Agriculture and Biomass Burning in the Philippines[Gay J. Perez, Josefino C. Comiso, and Mylene G. Cayetano]Section III Climate Drivers and Biomass BurningChapter 12 Fire Danger Indices and Methods: An Appraisal[Krishna Prasad Vadrevu]Chapter 13 Air Pollution Conditions near Peat Fire-Prone Areas duringEl Nino in Central Kalimantan, Indonesia[Hiroshi Hayasaka, Alpon Sepriando, Aswin Usup,and Naito Daisuke]Chapter 14 Biomass Burning and Haze in Indonesia, Long-Term ClimatePerspective, and Impact on Regional Air Quality[Sheila Dewi Ayu Kusumaningtyas, Edvin Aldrian,Sunaryo Sunaryo, and Roni Kurniawan]Chapter 15 Meteorological Drivers of Anomalous Wildfire Activityin the Western Ghats, India[Narendran Kodandapani]Chapter 16 Geochemical Evidence for Biomass Burning Signalson Tibetan Glaciers[Chao You and Chao Xu]

Crop straw (agricultural residue) is one of the most important biomass resources in China. Crop straw is either burned in the field or collected for recycling. Open burning of crop straw releases particulate matter and gaseous pollutants, which play a key role in poor air quality, prompting heavy haze episodes during the harvest season. Such episodes threaten human health and interfere with social and economic activities. In contrast, recycling of crop straw reduces open burning and avoids its negative environmental impacts. In fact, improving the efficiency of straw use contributes to a circular economy, dedicated to reducing waste, while also making the best use of any 'waste' in economically viable processes that increase its value. Returning straw to agricultural fields in China is the easiest solution and the most important measure promoted by governments promising clean technologies to replace open burning. Recently, China's municipalities have issued regulations forbidding outdoor burning of straw to reduce air pollution and have passed regulations to encourage farmers to use straw shredders during harvesting, and return crop straw as a bio-fertilizer. However, these regulations have not achieved the desired results, with ongoing open burning and reluctant use of straw on fields. In the first part of this research, urban residents' willingness of to pay (WTP) for a corn straw ban in Henan (China) was assessed using contingent valuation in a face-to-face survey. Such assessments are important for policy makers to determine the investment and policy instruments for regulating the environmental impacts of straw open burning. The expected WTP analyzed using the Tobit model was about 77 RMB per person per year for the total respondents and 143 RMB per person per year for respondents with positive WTP bids. Aggregate values were between 3.4 and 3.9 billion RMB, suggesting that the corn straw burning ban is of considerable economic value in Henan. In the second part of this research, the factors affecting farmers' willingness to participate in corn straw return and their willingness to accept compensation (WTA) were explored using a questionnaire survey and face-to-face interviews. A logistic regression model was used to assess adoption success, and the Tobit model was used for WTA analysis. High machinery costs, amount of straw returned, and slow decomposition rates of straw were the most significant factors negatively influencing adoption of this practice. They had a positive influence on the WTA. Poor quality of the straw was another significant factor reducing the probability of using straw return technology. Sown areas and soil improvements associated with adding straw wereoth positive factors determining adoption of the practice and negative determinants affecting WTA compensation. The mean WTA for the total respondent sample was 47 RMB per mu. In the third part of this research, a field experiment was carried out to compare the effects of tillage (minimum/full tillage) combined with corn straw return (mulching, incorporation, and removal) and irrigation (reduced/normal irrigation) methods on wheat productivity and water conservation. In 2013-2014, the yield for minimum tillage with residue mulch (MTm) was slightly but not significantly higher than the yield under full tillage with residue incorporation (FTi). Yields for MTm with reduced irrigation were 10.2% higher than FTi and reduced irrigation. The positive crop response to MTm may reflect higher topsoil moisture and soil temperature under MTm compared with FTi during winter. In conclusion, this study showed there is huge value to prohibiting open burning of corn straw to improve air quality. Despite machinery and operational problems that negatively influence farmers' enthusiasm for straw return, minimum tillage coupled with corn straw return does benefit subsequent wheat yields.

In order to assess the evolution of aerosol parameters affecting climate change, a long-term trend analysis of aerosol optical properties was performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann-Kendall (MK) statistical test associated with several pre-whitening methods and with Sen's slope was used as the main trend analysis method. Comparisons with general least mean square associated with autoregressive bootstrap (GLS/ARB) and with standard least mean square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficient trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficient time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, eastern/northern Europe and the Arctic, 22 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 26 % of sites have trends which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10-year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10-year trends are primarily found for earlier periods (10-year trends ending in 2010-2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10-year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10-year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10-year trends of the scattering coefficient - there is a shift to statistically significant negative trends in 2009-2012 for all stations in the eastern and central USA. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage provides insight into potential aerosol effects on climate changes. ; The authors would like to thank the numerous, but unfortunately unnamed, technical and scientific staff members of the stations as well as many students included in these analyses, whose dedication to quality for decades have made this paper possible. Provision of data from this study has mainly been acquired in the framework of NOAA-FAN (https://www.esrl.noaa.gov/gmd/aero/net/); ACTRIS, under the ACTRIS-2 (Aerosols, Clouds, and Trace gases Research InfraStructure) project supported by European Union (grant agreement no. 654109) and the ACTRIS PPP project under grant agreement no. 739530; and IMPROVE (http://vista.cira.colostate.edu/Improve/). Some European sites and measurements were also supported by the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air pollutants in Europe (EMEP) under UNECE. The authors are also grateful to the following persons and organizations. AMY: the Korea Meteorological Administration Research and Development Program "Development of Monitoring and Analysis Techniques for Atmospheric Composition in Korea" under grant KMA2018-00522 APP: Appalachian State College of Arts and Sciences, electronics technician Michael Hughes, machinist Dana Greene BEO: ACTRIS-BG project BIR: project no. 80026 "Arctic Monitoring and Assessment Programme" (AMAP) under EU action "Black Carbon in the Arctic". Aerosol optical/physical properties at Birkenes II are financed by the Norwegian Environment Agency CGO: the Australian Bureau of Meteorology and all the staff from the Bureau of Meteorology and CSIRO, particularly John Gras who instigated the measurements of aerosol scattering and absorption CPR: Para La Naturaleza and the nature reserve of Cabezas de San Juan and the support of grants AGS 0936879 and EAR-1331841. GSN: the Basic Science Research Program through the National Research Foundation of Korea (2017R1D1A1B06032548). SMR: the European Union Seventh Framework Programme under grant agreement no. 262254, the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654109 via project ACTRIS-2 and grant agreement no. 689443 via project iCUPE, the Academy of Finland (project no. 307331). IMPROVE: IMPROVE is a collaborative association of state, tribal, and federal agencies, and international partners. Support for IMPROVE nephelometers comes from the National Park Service. The assumptions, findings, conclusions, judgments, and views presented herein are those of the authors and should not be interpreted as necessarily representing the National Park Service (stations: ACA, BBE, CRG, GBN, GLR, GSM, HGC, MCN, MRN, MZW, NCC, RMN, SCN, SHN). IZO: Measurement Programme within the Global Atmospheric Watch (GAW) Programme at the Izaña Atmospheric Research Centre, financed by AEMET. JFJ: Urs Baltensperger, Günther Wehrle, Erik Herrmann; the International Foundation High Altitude Research Station Jungfraujoch and Gornergrat (HSFJG), the Swiss contributions (GAW-CH and GAW-CH-Plus) to the Global Atmosphere Watch programme of the World Meteorological Organization (WMO) which are coordinated by MeteoSwiss; the Swiss State Secretariat for Education, Research and Innovation, SERI, under contract number 15.0159-1 (ACTRIS-2 project). The opinions expressed and arguments employed herein do not necessarily reflect the official views of the Swiss Government. LLN: the Taiwan Environmental Protection Administration and the Ministry of Science and Technology for the support to individual PI's research funding. MSY: the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654109, MINECO (Spanish Ministry of Economy, Industry and Competitiveness) and FEDER funds under the PRISMA project (CGL2012-39623-C02/00) and under the HOUSE project (CGL2016-78594-R), the MAGRAMA (Spanish Ministry of Agriculture, Food and Environment) and the Generalitat de Catalunya (AGAUR 2014 SGR33, AGAUR 2017 SGR41 and the DGQA). Marco Pandolfi is funded by a Ramón y Cajal Fellowship (RYC-2013-14036) awarded by the Spanish Ministry of Economy and Competitiveness. MUK: the Ministry of Foreign Affairs of Finland, project grants (264242, 268004, 284536, and 287440) received from Academy of Finland; Business Finland and DBT, India sponsored project (2634/31/2015), the Centre of Excellence in Atmospheric Science funded by the Finnish Academy of Sciences (307331), and an esteemed collaboration of FMI and TERI. NOAA stations (BND, BRW, MLO, SGP, SPO, SUM, THD): Derek Hageman for all his programming efforts for NOAA and NFAN stations, John Ogren for initiating the expanded NFAN measurements and NOAA's Climate Program Office for funding PAY: the Swiss Federal Office for the Environment (FOEN). PUY: the staff of OPGC and LaMP, INSU-CNRS and the University Clermont Auvergne, and the financial support from ACTRIS-France National Research infrastructure and CNRS-INSU long-term observing program. SGP: the U.S. Department of Energy Atmospheric Radiation Measurement Program via Argonne National Laboratory, the DOE SGP ARM Climate Research Facility staff and scientists. TIK: the Aethalometer was supplied by Russ Schnell; Tiksi overall logistics and operations by Taneil Uttal and Sara Morris (NOAA/ESRL/PSD, Boulder, CO, USA). UGR: the Spanish Ministry of Economy and Competitiveness through projects CGL2016-81092-R, CGL2017-90884-REDT and RTI2018-101154-A-I00. WLG: China Meteorological Administration, National Scientific Foundation of China (41675129), National Key Project of the Ministry of Science and Technology of the People's Republic of China (2016YFC0203305 and 2016YFC0203306), and Basic Research Project of the Chinese Academy of Meteorological of Sciences (2017Z011) and the Innovation Team for Haze-fog Observation and Forecasts of China Meteorological Administration. ZEP: the Swedish EPA's (Naturvårdsverket) Environmental monitoring program (Miljöövervakning), the Knut-and-Alice-Wallenberg Foundation within the ACAS project (Arctic Climate Across Scales, project no. 2016.0024), the research engineers Tabea Henning, Ondrej Tesar and Birgitta Noone from ACES and the staff from the Norwegian Polar Institute (NPI), NPI for substantial long-term support in maintaining the measurements, Maria Burgos and Dominic Heslin-Rees (ACES) for preparing the data.

Aerosol particles are a complex component of the atmospheric system which influence climate directly by interacting with solar radiation, and indirectly by contributing to cloud formation. The variety of their sources, as well as the multiple transformations they may undergo during their transport (including wet and dry deposition), result in significant spatial and temporal variability of their properties. Documenting this variability is essential to provide a proper representation of aerosols and cloud condensation nuclei (CCN) in climate models. Using measurements conducted in 2016 or 2017 at 62 ground-based stations around the world, this study provides the most up-to-date picture of the spatial distribution of particle number concentration (Ntot) and number size distribution (PNSD, from 39 sites). A sensitivity study was first performed to assess the impact of data availability on Ntot's annual and seasonal statistics, as well as on the analysis of its diel cycle. Thresholds of 50g% and 60g% were set at the seasonal and annual scale, respectively, for the study of the corresponding statistics, and a slightly higher coverage (75g%) was required to document the diel cycle. Although some observations are common to a majority of sites, the variety of environments characterizing these stations made it possible to highlight contrasting findings, which, among other factors, seem to be significantly related to the level of anthropogenic influence. The concentrations measured at polar sites are the lowest (g1/4g102gcm-3) and show a clear seasonality, which is also visible in the shape of the PNSD, while diel cycles are in general less evident, due notably to the absence of a regular day-night cycle in some seasons. In contrast, the concentrations characteristic of urban environments are the highest (g1/4g103-104gcm-3) and do not show pronounced seasonal variations, whereas diel cycles tend to be very regular over the year at these stations. The remaining sites, including mountain and non-urban continental and coastal stations, do not exhibit as obvious common behaviour as polar and urban sites and display, on average, intermediate Ntot (g1/4g102-103gcm-3). Particle concentrations measured at mountain sites, however, are generally lower compared to nearby lowland sites, and tend to exhibit somewhat more pronounced seasonal variations as a likely result of the strong impact of the atmospheric boundary layer (ABL) influence in connection with the topography of the sites. ABL dynamics also likely contribute to the diel cycle of Ntot observed at these stations. Based on available PNSD measurements, CCN-sized particles (considered here as either >50gnm or >100gnm) can represent from a few percent to almost all of Ntot, corresponding to seasonal medians on the order of g1/4g10 to 1000gcm-3, with seasonal patterns and a hierarchy of the site types broadly similar to those observed for Ntot. Overall, this work illustrates the importance of in situ measurements, in particular for the study of aerosol physical properties, and thus strongly supports the development of a broad global network of near surface observatories to increase and homogenize the spatial coverage of the measurements, and guarantee as well data availability and quality. The results of this study also provide a valuable, freely available and easy to use support for model comparison and validation, with the ultimate goal of contributing to improvement of the representation of aerosol-cloud interactions in models, and, therefore, of the evaluation of the impact of aerosol particles on climate. ; NOAA base funding supports the observatories BRW, BND, MLO, SMO, SPO and THD, where efforts of the dedicated observatory staff and of programmer Derek Hageman are appreciated. BRW observations are also supported in part by the Atmospheric Radiation Measurement (ARM) user facility, a US Department of Energy (DOE) Office of Science user facility managed by the Biological and Environmental Research programme. Measurements at Welgegund are supported by North-West University, the University of Helsinki and the Finnish Meteorological Institute. This publication also forms part of the output of the Biogeochemistry Research Infrastructure Platform (BIOGRIP) of the Department of Science and Innovation of South Africa. Pallas and SMEAR II are grateful for the support of the Academy of Finland Centre of Excellence programme (project no. 272041), the Academy of Finland project Greenhouse gas, aerosol and albedo variations in the changing Arctic (project no. 269095), and the Novel Assessment of Black Carbon in the Eurasian Arctic: From Historical Concentrations and Sources to Future Climate Impacts (NABCEA, project no. 296302). Aerosol measurements at Anmyeon-do were supported by the Korea Meteorological Administration Research and Development Program "Development of Monitoring and Analysis Techniques for Atmospheric Composition in Korea" under grant KMA2018-00522. Measurements at Gosan were supported by the National Research Foundation of Korea (2017R1D1A1B06032548) and the Korea Meteorological Administration Research and Development Program under grant KMI2018-01111. The Lulin station is operated under the grants funded by the Taiwan Environmental Protection Administration. WLG is supported by the China Meteorological Administration, where efforts of the dedicated observatory staff are appreciated. Sites PDM, PUY, GIF, CHC and RUN are partially operated with the support of CNRS-INSU under the long-term observation programme and the French Ministry for Research under the ACTRIS-FR national research infrastructure. PDM and GIF received specific support from the French Ministry of the Environment. ATMO Occitanie is mentioned for sampling operations at PDM. Measurements at SIRTA are hosted by CNRS and by the alternative energies and atomic energy commission (CEA) with additional contributions from the French Ministry of the Environment through its funding to the reference laboratory for air quality monitoring (LCSQA). PUY is grateful for support from ATMO Auvergne Rhône Alpes for sampling operations and the support from the personnel of the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC). The specific support of the Institut de Recherche et Développement (IRD) in France and the Universidad Mayor de San Andrés in Bolivia support operations at CHC operations. The Steamboat Ski Resort provided logistical support and in-kind donations for SPL. The Desert Research Institute is a permittee of the Medicine Bow–Routt National Forests and an equal opportunity service provider and employer. SPL appreciates the extensive assistance of the NOAA/ESRL Federated Aerosol Network, of Ian McCubbin, site manager of SPL, and of Ty Atkins, Joe Messina, Dan Gilchrist and Maria Garcia, who provided technical assistance with the maintenance and data quality control for the aerosol instruments. SGP measurements/mentorship were supported by DOE-7F-30118 and staff on site. The Cape Grim Baseline Air Pollution Monitoring Station is grateful to the Australian Bureau of Meteorology for their long-term and continued support and all the staff from the Bureau of Meteorology and CSIRO, who have contributed to the generation of records reported here. The aerosol measurements at the Jungfraujoch were conducted with financial support from MeteoSwiss (GAW-CH aerosol monitoring programme) and from the European Union as well as the Swiss State Secretariat for Education, Research and Innovation (SERI) for the European Research Infrastructure for the observation of Aerosol, Clouds and Trace Gases (ACTRIS). The International Foundation High Altitude Research Station Jungfraujoch and Gornergrat (HFSJG) is mentioned for providing the research platform at the Jungfraujoch. The aerosol measurements at Kosetice received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement no. 654109 and from the project for support of the national research infrastructure ACTRIS – participation of the Czech Republic (ACTRIS-CZ – LM2015037) supported by the Ministry of Education, Youth and Sports of CR within National Sustainability Program I (NPU I), grant agreement no. LO1415. The measurements were also supported by ERDF "ACTRIS-CZ RI" (no. CZ.02.1.01/0.0/0.0/16_013/0001315). Measurements at the Madrid site were funded by the following projects: CRISOL (CGL2017–85344-R MINECO/AEI/FEDER, UE), TIGAS-CM (Madrid Regional Government Y2018/EMT5177), AIRTEC-CM (Madrid Regional Government P2018/EMT4329), REDMAAS2020 (RED2018-102594-T CIENCIA) and Red de Excelencia ACTRIS-ESPAÑA (CGL2017-90884-REDT). Measurements at Montsec and Montseny were supported by the Spanish Ministry of Economy, Industry and Competitiveness and FEDER funds under project HOUSE (CGL2016-78594-R) and by the Generalitat de Catalunya (AGAUR 2017 SGR41 and the DGQA). Aerosol measurements at El Arenosillo Observatory are supported by the National Institute for Aerospace Technology and by different R&D projects of the Ministerio Español de Economía, Industria y Competitividad (MINECO). Aerosol measurements at UGR are supported by the Spanish Ministry of Economy and Competitiveness through projects no. CGL2016-81092-R, CGL2017-90884-REDT, RTI2018-097864-B-I00 and PGC2018-098770-B-I00 and by the Andalusia Regional Government through project no. P18-RT-3820. FKL, HAC and DEM are grateful for funding by project PANhellenic infrastructure for Atmospheric Composition and climate change (MIS 5021516), which is implemented under action Reinforcement of the Research and Innovation Infrastructure, funded by operational programme Competitiveness, Entrepreneurship and Innovation (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund). CPC measurements at Sonnblick are supported by the Climate and Air Quality Commission of the Austrian Academy of Sciences and the office of the provincial government Salzburg, Unit 5/02. At CMN, aerosol measurements were partially supported by the Italian Ministry of Research and Education. Measurements at Birkenes II are financed by the Norwegian Environment Agency. VAV is grateful for various Swedish FORMAS, Swedish Research Council (VR) grants and the Magnus Bergvall and Märta och Erik Holmberg foundations and the Swedish EPA for making the research possible at the VAV site. NMY wishes to thank the many technicians and scientists of the Neumayer overwintering crews, whose outstanding commitment enabled continuous, high-quality aerosol records over many years. Gunter Löschau is acknowledged for his contribution to the data acquisition at ANB, DTC and DRN. Financial support This research was supported by the European Commission's Horizon 2020 Framework Programme (ACTRIS2 (grant agreement no. 654109)), the University of Helsinki, the Finnish Meteorological Institute, the Department of Science and Innovation of South Africa, the Academy of Finland Centre of Excellence programme (project no. 272041), the Academy of Finland project Greenhouse gas, aerosol and albedo variations in the changing Arctic (project no. 269095), the Novel Assessment of Black Carbon in the Eurasian Arctic: From Historical Concentrations and Sources to Future Climate Impacts (NABCEA, project no. 296302), the Korea Meteorological Administration Research and Development Program "Development of Monitoring and Analysis Techniques for Atmospheric Composition in Korea" (grant no. KMA2018-00522), the National Research Foundation of Korea (grant no. 2017R1D1A1B06032548), the Korea Meteorological Administration Research and Development Program (grant no. KMI2018-01111), the Taiwan Environmental Protection Administration, the China Meteorological Administration, the National Scientific Foundation of China (41675129, 41875147), the National Key R&D Program of the Ministry of Science and Technology of the People's Republic of China (grant no. 2016YFC0203305 and 2018YFC0213204), the Chinese Academy of Meteorological Sciences (2020KJ001), the Innovation Team for Haze-fog Observation and Forecasts of MOST and CMA, CNRS-INSU, the French Ministry for Research under the ACTRIS-FR national research infrastructure, the French Ministry of the Environment, MeteoSwiss (GAW-CH aerosol monitoring programme), the Swiss State Secretariat for Education, Research and Innovation (SERI), the Ministry of Education, Youth and Sports of CR within National Sustainability Program I (NPU I, grant no. LO1415), ERDF "ACTRISCZ RI" (grant no. CZ.02.1.01/0.0/0.0/16_013/0001315), CRISOL (CGL2017-85344-R MINECO/AEI/FEDER, UE), TIGAS-CM (Madrid Regional Government Y2018/EMT-5177), AIRTEC-CM (Madrid Regional Government P2018/EMT4329), REDMAAS2020 (RED2018-102594-T CIENCIA), Red de Excelencia ACTRIS-ESPAÑA (CGL2017-90884-REDT), the Spanish Ministry of Economy, Industry and Competitiveness, FEDER funds (project HOUSE, grant no. CGL2016-78594-R), the Generalitat de Catalunya (AGAUR 2017 SGR41 and the DGQA), the National Institute for Aerospace Technology, the Ministerio Español de Economía, Industria y Competitividad (MINECO), the Spanish Ministry of Economy and Competitiveness (projects no. CGL2016-81092-R, CGL2017-90884-REDT, RTI2018-097864-B-I00 and PGC2018-098770-B-I00), the Andalusia Regional Government (project no. P18-RT-3820), the PANhellenic infrastructure for Atmospheric Composition and climate change (MIS 5021516), Research and Innovation Infrastructure, Competitiveness, Entrepreneurship and Innovation (grant no. NSRF 2014-2020), the Italian Ministry of Research and Education, the Norwegian Environment Agency, Swedish FORMAS, the Swedish Research Council (VR), the Magnus Bergvall foundation, the Märta och Erik Holmberg foundation, and the Swedish EPA. ; Peer reviewed