Sources and implications of black carbon (BC) and mineral dust (MD) on two glaciers on the central Tibetan Plateau were estimated based on in situ measurements and modeling. The results indicated that BC and MD accounted for 11 +/- 1% and 4 +/- 0% of the albedo reduction relative to clean snow, while the radiative forcing varied between 11 and 196 and 1-89 W m(-2), respectively. Assessment of BC and MD contributions to the glacier melt can reach up 88 to 434 and 35 to 187 mm w.e., respectively, contributing 9-23 and 4-10% of the total glacier melt. A footprint analysis indicated that BC and MD deposited on the glaciers originated mainly from the Middle East, Central Asia, North China and South Asia during the study period. Moreover, a potentially large fraction of BC may have originated from local and regional fossil fuel combustion. This study suggests that BC and MD will enhance glacier melt and provides a scientific basis for regional mitigation efforts.

PM2.5 impacts the atmospheric temperature structure through scattering or absorbing solar radiation, whose concentration and composition can affect the impact. This study calculated the effect of PM2.5 on the temperature structures in the urban centre and the suburbs of Nanjing, as well as their differences. The results show that the optical parameters, atmospheric heating rate, radiative forcing, and temperature are all impacted by the concentration and composition of PM2.5. The uneven distribution of PM2.5 influences the differences in those factors between the urban centre and suburbs. In spring, summer, autumn, and winter, surface temperatures in the urban centre were approximately 283 K, 285 K, 305 K, and 277 K, while those in the suburbs were approximately 282 K, 283 K, 304 K, and 274 K. The urban heat island intensity has been reduced by 0.1-0.4 K due to the presence of PM2.5 in Nanjing. Due to the black carbon component's warming effect on the top of the boundary layer, the impact of PM2.5 on the urban heat island intensity profile drops quickly at the 0.75-1.25 km. PM2.5 may mask the warm city problem and have a more complex impact on the urban climate.

Aviation emissions are the only direct source of anthropogenic particulate pollution at high altitudes, which can form con-trails and contrail-induced clouds, with consequent effects upon global radiative forcing. In this study, we develop a pre-dictive model, called APMEP-CNN, for aviation non-volatile particulate matter (nvPM) emissions using a convolutional neural network (CNN) technique. The model is established with data sets from the newly published aviation emission databank and measurement results from several field studies on the ground and during cruise operation. The model also takes the influence of sustainable aviation fuels (SAFs) on nvPM emissions into account by considering fuel properties. This study demonstrates that the APMEP-CNN can predict nvPM emission index in mass (EIm) and number (EIn) for a number of high-bypass turbofan engines. The accuracy of predicting EIm and EIn at ground level is significantly improved (R2 = 0.96 and 0.96) compared to the published models. We verify the suitability and the applicability of the APMEP-CNN model for estimating nvPM emissions at cruise and burning SAFs and blend fuels, and find that our predictions for EIm are within & PLUSMN;36.4 % of the measurements at cruise and within & PLUSMN;33.0 % of the measurements burning SAFs in av-erage. In the worst case, the APMEP-CNN prediction is different by -69.2 % from the measurements at cruise for the JT3D-3B engine. Thus, the APMEP-CNN model can provide new data for establishing accurate emission inventories of global aviation and help assess the impact of aviation emissions on human health, environment and climate.Synopsis: The results of this paper provide accurate predictions of nvPM emissions from in-use aircraft engines, which im-pact airport local air quality and global radiative forcing.

Aerosol behavior over the Himalayas plays an important role in the regional climate of South Asia. Previous studies at highaltitude observatories have provided evidence of the impact of long-range transport of pollutants from the Indo-Gangetic Plain (IGP). However, little information exists for the valley areas in the high Himalayas where significant local anthropogenic emissions can act as additional sources of short-living climate forcers and pollutants. The valley areas host most economic activities based on agriculture, forestry, and pilgrimage during every summer season. We report here first measurements at a valley site at similar to 2600 m a.s.l. on the trek to the Gangotri glacier (Gaumukh), in the Western Himalayas, where local infrastructures for atmospheric measurements are absent. The study comprised short-term measurement of aerosols, chemical characterization, and estimation of aerosol radiative forcing (ARF) during the winter and summer periods (2015-2016). The particulate matter mass concentrations were observed to be higher than the permissible limit during the summer campaigns. We obtained clear evidence of the impact of local anthropogenic sources: particulate nitrate is associated with coarse aerosol particles, the black carbon (BC) mass fraction appears undiluted with respect tomeasurements performed in the lower Himalayas, and inwinter, both BC and sulfate concentrations in the valley site are well above the background levels reported from literature studies for mountain peaks. Finally, high concentrations of trace metals such as copper point to anthropogenic activities, including combustion and agriculture. While most studies in the Himalayas have addressed pollution in the high Himalayas in terms of transport from IGP, our study provides clear evidence that local sources cannot be overlooked over the high-altitude Himalayas. The estimated direct clear-sky ARF was estimated to be in the range of -0.1 to +1.6Wm(-2), with significant heating in the atmosphere over the highaltitude Himalayan study site. These results indicate the need to establish systematic aerosol monitoring activities in the high Himalayan valleys.

In order to quantify air pollution effects on climate change, we investigated the climate response associated with anthropogenic particulate matters (PMs) by dividing fine PM (PM2.5, particle size 2.5 mu m) in great detail in this work, with an aerosol-climate coupled model. We find that the changes in PM2.5 and CPM are very different and thus result in different, even opposite effects on climate, especially on a regional scale. The column burden of PM2.5 increases globally from 1850 to the present, especially over Asia's southern and eastern parts, whereas the column concentration of CPM increases over high-latitude regions and decreases over South Asia. The resulted global annual mean effective radiative forcing (ERF) values due to PM2.5 and CPM changes are -1.21 W center dot m(-2) and -0.24 W center dot m(-2), respectively. Increases in PM2.5 result in significant cooling effects on the climate, whereas changes in CPM produce small and even opposite effects. The global annual mean surface air temperature (SAT) decreases by 0.94 K due to PM2.5 increase. Coolings caused by increased PM2.5 are more apparent over Northern Hemisphere (NH) terrain and ocean at mid- and high latitudes. Increases in SATs caused by increased CPM are identified over high latitudes in the NH, whereas decreases are identified over mid-latitude regions. Strong cooling due to increased PM2.5 causes a southward shift of the Intertropical Convergence Zone (ITCZ), whereas the Hadley circulation associated with CPM is enhanced slightly over both hemispheres, along with the weak movement of corresponding ITCZ. The global annual mean precipitation decreases by approximately 0.11 mm day(-1) due to the increased PM2.5. Generally, PM2.5 concentration changes contribute more than 80% of the variation caused by all anthropogenic aerosols in ERF, SAT, cloud fraction, and precipitation.

Low- and middle-income countries have the largest health burdens associated with air pollution exposure, and are particularly vulnerable to climate change impacts. Substantial opportunities have been identified to simultaneously improve air quality and mitigate climate change due to overlapping sources of greenhouse gas and air pollutant emissions and because a subset of pollutants, short-lived climate pollutants (SLCPs), directly contribute to both impacts. However, planners in low- and middle-income countries often lack practical tools to quantify the air pollution and climate change impacts of different policies and measures. This paper presents a modelling framework implemented in the Low Emissions Analysis Platform - Integrated Benefits Calculator (LEAP-IBC) tool to develop integrated strategies to improve air quality, human health and mitigate climate change. The framework estimates emissions of greenhouse gases, SLCPs and air pollutants for historical years, and future projections for baseline and mitigation scenarios. These emissions are then used to quantify i) population-weighted annual average ambient PM2.5 concentrations across the target country, ii) household PM2.5 exposure of different population groups living in households cooking using different fuels/technologies and iii) radiative forcing from all emissions. Health impacts (premature mortality) attributable to ambient and household PM2.5 exposure and changes in global average temperature change are then estimated. This framework is applied in Bangladesh to evaluate the air quality and climate change benefits from implementation of Bangladesh's Nationally Determined Contribution (NDC) and National Action Plan to reduce SLCPs. Results show that the measures included to reduce GHGs in Bangladesh's NDC also have substantial benefits for air quality and human health. Full implementation of Bangladesh's NDC, and National SLCP Plan would reduce carbon dioxide, methane, black carbon and primary PM2.5 emissions by 25%, 34%, 46% and 45%, respectively in 2030 compared to a baseline scenario. These emission reductions could reduce population-weighted ambient PM2.5 concentrations in Bangladesh by 18% in 2030, and avoid approximately 12,000 and 100,000 premature deaths attributable to ambient and household PM2.5 exposures, respectively, in 2030. As countries are simultaneously planning to achieve the climate goals in the Paris Agreement, improve air quality to reduce health impacts and achieve the Sustainable Development Goals, the LEAP-IBC tool provides a practical framework by which planners can develop integrated strategies, achieving multiple air quality and climate benefits.

In this work we present the results of the four-years (2015-2018) data-analysis of aerosols optical extensive properties such as scattering (sigma(sc)) and backscattering coefficients (sigma(bsc)), scattering Angstrom exponent (SAE), single scattering albedo (SSA), and asymmetry parameter (g). They were measured at three GAW (Global Atmosphere Watch-WMO) regional observatories in the South of Italy: CGR (Capo Granitola), LMT (Lamezia Terme) and ECO (Lecce). The aim of this work is to characterize the optical properties of the aerosols, in terms of scattering, absorption and radiative forcing, to study their relationship with the equivalent black carbon (eBC) mass concentration, meteorological parameters and to evaluate their variability in the Central Mediterranean area. From the mean values of SAE (1.73 ECO, 1.93 LMT) and SSA (0.81 ECO, 0.78 LMT) observations can be argued that ECO and LMT are mainly influenced by ultrafine particles, while CGR, with mean values of SAE and SSA of 1.15 and 0.87, respectively, is characterized by natural sources, mainly marine. In all stations, g(550) is very similar, 0.68 at CGR and 0.63 at LMT, with the greatest value (0.70) at ECO. The aerosol optical properties, at the three stations, are significantly influenced by the meteorological conditions. The daily pattern for eBC concentration at ECO and LMT is essentially influenced by local activities, namely due to vehicular traffic, and, for LMT, to local sea-land breeze circulation. Wood burning is the main source contribute to eBC concentration in the remote site of CGR. Aerosols optical properties were analysed in the cold (from October to March) and warm (from April to September) period in the three observatories to highlight the behaviour of optical parameters as a response to changing black carbon concentration, especially, from local sources. As expected, three observatories exhibited low values of SSA, during the cold season, 0.87 at CGR, 0.78 at LMT and 0.80 at ECO, which confirm an increment of industrial/traffic and wood combustion contributions at the three observatories. SSA values are very similar in warm and cold period, especially in the middle part of the day. A persistent and important results in the findings of this study is that aerosol optical properties vary widely from station to station throughout the central Mediterranean basin. Thus, the wide spatial and temporal variability of aerosol characteristics in the basin need additional investigations to study the relationship between particle size distribution, optical parameters and local sources contribution at the three sites. Further, our results show a negative radiative forcing of aerosols, with mean values of -58.8 at CGR, -45.4 at LMT and - 55.9 at ECO, according also to several studies in central Mediterranean area.

Sources and implications of black carbon (BC) and mineral dust (MD) on two glaciers on the central Tibetan Plateau were estimated based on in situ measurements and modeling. The results indicated that BC and MD accounted for 11 +/- 1% and 4 +/- 0% of the albedo reduction relative to clean snow, while the radiative forcing varied between 11 and 196 and 1-89 W m(-2), respectively. Assessment of BC and MD contributions to the glacier melt can reach up 88 to 434 and 35 to 187 mm w.e., respectively, contributing 9-23 and 4-10% of the total glacier melt. A footprint analysis indicated that BC and MD deposited on the glaciers originated mainly from the Middle East, Central Asia, North China and South Asia during the study period. Moreover, a potentially large fraction of BC may have originated from local and regional fossil fuel combustion. This study suggests that BC and MD will enhance glacier melt and provides a scientific basis for regional mitigation efforts.

Understanding of carbonaceous aerosols from different combustion sources and their optical properties are important to better understand atmospheric aerosol sources and estimate their radiative forcing. In this study, eight organic carbon (OC) and elemental carbon (EC) sub-fractions and light absorption properties of EC are investigated using thermal/optical method and compared among six typical solid and liquid fossil fuel combustion sources (e.g., coal combustion, industry, power plant, diesel and gasoline vehicle, and ship emissions) and within each source type, with consideration of different fuel types and combustion conditions. The results indicate that OC and EC sub-fraction distributions and mass absorption efficiency of EC (MAE(EC)) are sensitive and specific to sources, fuels, combustion and operating conditions. The differences in carbon fractions and AE(EC) between solid and fossil fuel source emissions are statistically significant (p < 0.05). The average MAE(EC) from liquid fossil fuel sources (7.9 +/- 3.5 m(2)/g) are around1.5-fold higher than those from solid fossil fuels (5.3 +/- 4.0 m(2)/g). Correlation analysis indicates that light attenuation of EC positively correlates with EC1 and EC2 fractions with correlation coefficients (r) around 0.6, while negatively correlates with the percentages of OC2 and OC3 in total carbon. Inter-comparisons of distributions of carbon sub-fractions and MAE(EC) from different coal samples indicate the tested new stoves and honeycomb-like shape may contribute to lower EC emission factors but with stronger light absorptivity of EC, suggesting curbing short-lived pollutants (e.g., EC) with improvement of coal stoves and clean coal at current stage might not always result in co-benefits of air quality and climate.

The present study examines the effect of Diwali festival (17-21 October 2017; 19th October was the Diwali day) on aerosol characteristics over Patiala, northwestern part of India. Diwali being one of the major festivals of India that falls between mid-October and mid-November is celebrated with full enthusiasm by burning crackers, fireworks, etc. During this period, the study site also is engulfed with high aerosol loading because of extensive paddy residue burning emission. During Diwali event, a particulate matter (PM10) concentration varies from 132 to 155 mu gm(-3), while a mass concentration of black carbon aerosols varies from 6 to 9 mu gm(-3) with the maximum concentration on post-Diwali day. Aerosol optical depth (AOD(500)) was maximum (0.852) on post-Diwali day indicating the additional loading of submicron particles due to burning of crackers and fireworks. The magnitude of single scattering albedo (SSA(500)) decreases to a minimum value around 0.864 showing abundance of absorbing aerosols on Diwali affected days (19th and 20th October). A sudden jump of +12.9Wm(-2) in atmospheric radiative forcing resulting in a heating rate of up to 1.4Kday(-1) on next day of Diwali shows the warming state of the lower and middle atmosphere.