Simulation of Aerosol-Induced Climate Change due to Emission Change by Composition Using a Coupled Atmosphere-Ocean Model

Toshihiko TAKEMURA

Kyushu University, Japan

Abstract

Until the early 2010s, the assessment of climate change by aerosols was often based only on the calculation of radiative forcing. Since then, climate models that explicitly include the process of aerosol- induced climate change have matured, and advances in computation have led to progress in the evaluation of specific climate change by composition. However, the surface temperature change by each anthropogenic component of short-lived climate forcers (SLCFs) including aerosols shown in the Summary for Policymakers of the IPCC WG1 AR6 was estimated from the effective radiative forcing calculated in CMIP6 using a two-layer emulator. Coupled atmosphere-ocean model simulations are essential to quantitatively evaluate climate change caused by SLCFs, which have a highly heterogeneous regional distribution. In this talk, recent progress in quantitative understanding of aerosol-induced climate change using climate models will be outlined and future research will be discussed.

Aerosol Effects on Weather and Climate through Interaction with Clouds

Jen-Ping CHEN

National Taiwan University, Taiwan

Abstract

Aerosol particles interact strongly with the clouds, consequently influencing weather and climate. The climate effects proceed directly through the scattering/absorption of solar radiation and indirectly through interactions with clouds. The weather effects mainly result from aerosols’ influencing the production of cloud particles and precipitation efficiency by acting as cloud condensation nuclei or ice nuclei. The precipitation response to aerosol effects is revealed not only in the absolute amount but also in the timing of precipitation. Thermodynamic effects, such as convective invigoration, may also occur due to the inhibition of liquid-phase microphysics, leading to enhanced ice-phase processes. Aerosols’ role in these processes is complicated due to the wide variety of aerosol compositions and spatial inhomogeneity. A few numerical simulation results will be used in this presentation to demonstrate aerosols’ effects on climate and weather systems.

Measuring Atmospheric Black Carbon, Its Optical Properties and Mixing State

James ALLAN

The University of Manchester, UK

Abstract

Black carbon is a major component of anthropogenic pollution, being produced through combustion processes, however its impacts on the environment are complex and hard to predict. It can influence meteorology and climate through absorption and scattering of shortwave radiation, acting as cloud nuclei and causing snow melt after deposition, but the exact effects depend heavily on its precise microphysical nature, other chemical species present (“coatings”) and its transport and lifetime within the atmosphere. The study of black carbon continues to be of relevance to atmospheric aerosol science, as combustion emissions change through economic development, adoption of new technologies and switches to new, more sustainable fuel sources. Here I will give examples of how the use of online instrumentation, in particular the DMT Single Particle Soot Photometer (SP2) has given insight into the sources, processes and impacts of atmospheric black carbon. This includes novel combinations of instruments designed to study not just traditional metrics such as mass concentration and mass absorption cross section, but also the precise mixing state and evolution in the atmosphere. Laboratory measurements of black carbon are also performed using the same instrumentation, which allows us to determine detailed chemical and physical parameters that are used to interpret and model their behaviour in the atmosphere. However, emissions are known to vary strongly according to the fuel and combustion conditions, so additional insight can be gained by studying small-scale combustion processes under highly controlled conditions.

Asian Aerosols as Air Pollutants and SLCFs: IPCC AR6 Report and Beyond

Yugo KANAYA

Japan Agency for Marine-Earth Science and Technology, Japan

Abstract

The Intergovernmental Panel on Climate Change (IPCC) Working Group 1 Sixth Assessment Report (AR6) was publicized in August 2021 (IPCC, 2021), after expert reviews of drafts and revisions. I was appointed as a Review Editor of its Chapter 6 (Short-lived Climate Forcers (SLCFs)) and participated in the process. In this presentation, several key statements from the report and selected information from cited literatures relevant to Asian aerosols and their precursors are to be highlighted. They include several aspects: e.g., emissions, atmospheric processes connecting emissions to concentrations, and their future projections with associated climate and health impacts.

Photodissociation of Particulate Nitrate as a source of Cl2 and Impact on Air Quality in a Polluted Coastal Area

Tao WANG

Hong Kong Polytechnic University, Hong Kong, China

Abstract

Chlorine atoms (Cl) are highly reactive and can strongly influence atmospheric abundances of climate and air quality-relevant trace gases such as methane and ozone (O3). Yet, its abundances, sources and impact in polluted regions are poorly understood. In autumn 2018, we observed unprecedented levels of daytime Cl2 (up to 1 ppbv, with an average of ~400 pptv) in a coastal area in Hong Kong, indicating the presence of a large daytime source as the lifetime of Cl2 is only ~7 minutes at noon. This source was positively correlated with the product of solar actinic flux, nitrate and aerosol surface areas, suggesting a photochemical source of Cl2 involving nitrate and occurring at air-particle interface. Illuminating acid doped nitrate-NaCl solution with a xenon lamp in laboratory revealed that photolysis of particulate nitrate under acidic conditions (pH <3.0) could activate chloride, the lab derived Cl2 production could account for a great fraction of the observed daytime Cl2 production. The high Cl2 concentrations observed at the site increased the atmospheric oxidation rate of volatile organic compounds (VOCs) by 24 to 132%, ROx radical by 4-27%, and daytime O3 integrated production by 17%. Given the ubiquitous existence of chloride, nitrate, and acidic aerosols, we propose that nitrate photolysis is a significant daytime chlorine source globally. This so far unaccounted for new source of chlorine can have substantial impacts on ozone and other air pollutants. Our study also suggests additional benefit of widely adopted NOx and SO2 control through lessening Cl2 production and secondary pollution. For detail, see: https://www.nature.com/articles/s41467-022-28383-9

Transport and Transformation of Urban Air Pollutants

Charles CHOU

Academia Sinica, Taiwan

Abstract

Along with the industrialization and urbanization, a large fraction of population is now living and/or workingin urban areas, particularly the megacities (UNDESA, 2018). The emissions of air pollutants from anthropogenic activities have caused significant impacts on the health of urban inhabitants (Lelieveld et al., 2015). Besides, the urban air pollutants can transport over a long distance and deteriorate air quality in the downwind areas.  Moreover, the primary air pollutants are known to participate atmospheric reactions and, consequently, produce secondary air pollutants, in particular ozone and secondary aerosols. Thus, understanding the mechanisms underlying the emission, transport and transformation of urban air pollutants is essential to the sustainable development of our society.

Patterns of Size-fractionated PMs and PAHs in Urban and Rural Areas of Northern Thailand 

Somporn CHANTARA

Chiang Mai University, Thailand

Abstract

Size distribution of atmospheric particles is important because of deposit capability of various particle sizes in different parts of respiratory system (Kim et al., 2015). In Southeast Asia, only a few works reported on size-fractionated atmospheric particles and particle-bound PAHs especially in submicron or ultrafine levels, which are much more harmful to human health. This study aims to find out distribution pattern of size-fractionated atmospheric particles and their PAHs content in urban and rural environments during intensive burning and non-burning periods in Northern Thailand.

Identification of Metal Pollutants in Ambient Air (Case Study: West Surabaya, East Java, Indonesia)

Arie Dipareza SYAFEI

Institut Teknologi Sepuluh Nopember, Indonesia

Abstract

The western area of Surabaya is utilized for industrial space, warehousing, final disposal sites, and port areas. Activities in these areas produce emissions, particularly PM2.5 and PM10. They contain metals and cause respiratory disorders and death. Therefore, it is necessary to determine the concentrations of PM2.5 and PM2.5–10 and the heavy metals contained in the PMs. Sampling was conducted using a Gent Stacked Filter Unit. The samples were analyzed using gravimetry to determine mass concentrations and X-Ray Fluorescence to determine the elements and concentrations. Positive Matrix Factorization used to identify potential pollutant sources and Conditional Probability Function used to determine the source locations of pollutants. The observed concentrations of PM2.5 and PM10 are 11.45 μg/Nm3 and 26.98 μg/Nm3. The 18 elements are identified in the PMs. Potential sources of PM2.5 pollutants are metal industries, biomass burning, non-ferrous metal industries, transportation, iron and steel industries, construction, dust, port, and Pb industries. Potential sources of PM2.5–10 pollutants are construction, dust, transportation, non-ferrous metals industries, and Ni industries. The estimated source locations of the pollutants are spread out from north to southwest.  Based on this analysis, the concentrations of PM2.5, PM2.5–10, and metal elements met air quality standards.

Exposure of Malaysian School Children to Air Pollutants and Health Risk and Impact Assessment

Juliana Binti JALALUDIN

Universiti Putra Malaysia, Malaysia

Abstract

Air quality in both outdoor and indoor environments in Malaysia have been affected by the urbanization process for the past years. Breathing this polluted air can cause significant health impacts on the recipient throughout their life, especially children as their exposure begins at an early age. Children’s environmental health has been recognized as the top environmental health threat in Malaysia. Mechanisms underlying the associations between air pollutants and health effects have been explored via biomarkers to understand the roles of inflammatory responses, genetic variants, and epigenetic changes at the molecular level. This talk will address evidence from previous relevant findings with highlights on assessing children’s health risks and impacts.

Emissions and Reduction at the Source of Air Contaminants from Charcoal Making Process - A Case Study in the Vietnamese Mekong Delta

Toan Pham VAN

Can Tho University, Viet Nam

Abstract

Charcoal is a fuelwood commonly used for household purposes in the developing word, especially Africa and South East Asia nations. Unfortunately, airborne emissions from the charcoal making process could affect human health and the environment. A series of study on the impact of charcoal production was performed in the Vietnamese Mekong Delta. Study results revealed that current charcoal making process caused a substantial loss of carbon and emitted the products of incomplete combustion. These contaminants caused negatively impacts on the social and environmental aspects. Local residents were at high risks of charcoal particles. Carbon dioxide and incomplete combustion products were highly potential causes of global warming. An air pollution control system proved to be an urgent solution before finding alternatives to control the impacts of charcoal production.