Orals: Mon, 28 Apr | Room 0.11/12
The central Arctic ocean (CAO) is transforming rapidly due to climate change with wide spread consequences. Therefore, understanding the mechanisms of change, in particular related to the surface energy budget, is indispensable. Aerosols affect the surface radiation budget both directly and indirectly through interactions with clouds.
In the CAO, cloud formation and radiative processes are particularly susceptible to aerosols, because their number concentration can be very low. To date, the climatic effects of aerosols in the CAO have mostly been constrained in terms of anthropogenic emissions and direct radiation interactions, where a significant warming contribution has been found. What is missing, are effects of natural aerosols and aerosol-cloud interactions. It is hence of utmost importance to fully understand the present-day aerosol-climate interactions, constrain the most relevant processes and how they relate to Arctic change in order to anticipate future impacts.
However, the CAO is an inherently difficult place to study due to its limited physical accessibility as well as hampered satellite observations. To mitigate the observational scarcity, the ‘Multidisciplinary Observatory for the Study of Arctic Change’ (MOSAiC) expedition drifted for one year between fall 2019 and 2020 in the CAO.
In this contribution, we will present our insights from one year of aerosol observations that include variables such as cloud condensation nuclei and ice nucleating particle number concentrations, particle number size distributions, bulk and single particle chemical composition as well as optical properties. This presentation will specifically focus on unprecedented insights, for example the roles of processes like blowing snow and sea spray emissions and warm air mass intrusions, as well as the abundance of biogenic and biological aerosol components.
How to cite: Schmale, J., Heutte, B., Bergner, N., Beck, I., Dada, L., Angot, H., Mavis, C., Barry, K., Mirrieless, J., Boyer, M., Quelever, L., Jokinen, T., Pratt, K., and Creamean, J.: What have we learned from one year of aerosol observations in the central Arctic during the MOSAiC expedition?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8039, https://doi.org/10.5194/egusphere-egu25-8039, 2025.
The Hindu Kush Himalayan (HKH) region holds substantial strategic significance owing to its extensive reserves of pristine water in the form of glaciers. In recent years, significant levels of particulate pollution have been documented within the high-altitude regions of the Himalayas. The influence of the albedo changes due to aerosol pollutants deposition on the glacial mass balance due to an excess and earlier snow melting, and thereby an earlier glacier runoff, is expected to impact the downstream hydrology. This is specifically of concern for the HKH region as the Himalayan glaciers are the source of major rivers in South Asia. The remote topography and severe weather conditions prevalent in the Himalayan region, however pose challenges to obtaining consistent spatial-temporal measurements of atmospheric aerosol concentration and their presence in snow. The simulated aerosol species concentration, using atmospheric chemical transport models (CTMs), which is validated by measurements, can be utilized to predict the spatial mapping of aerosol species distribution over the HKH region. In order to spatially map the estimates of atmospheric aerosol species concentration and their concentration in snow as adequately as possible, including the corresponding snow-albedo reduction over the HKH region, an integrated approach merging the relevant information from observations with a relatively consistent atmospheric chemical transport model estimates are applied in the present study.
We examine the cumulative and relative impact of aerosol species over the HKH region, including aerosol concentration in the snow, impacts on snow albedo re duction (SAR) and enhanced annual glacier snowmelt runoff identifying the hotspot locations. This is done evaluating aerosols transport simulations corresponding to dust, sulfate, and organic carbon (OC) aerosols relative to black carbon (BC) in free-running (freesimu) atmospheric general circulation model (GCM) and application of constrained (constrsimu) aerosol simulations, aerosol-snow radiative interaction model, and a novel hypsometric glacier energy mass balance model. Estimates for aerosol species concentrations from freesimu demonstrated increased accuracy at high-altitude (HA) stations compared to their performance at low-altitude (LA) stations. Conversely, estimates from constrsimu exhibited notably better performance at LA stations. The pre-monsoon aerosol species deposited in snow (> 850 µg kg−1 over Gangotri and Chorabari) were the highest among glaciers, being about 40% greater than winter with OC including BC over selected glaciers and dust across all glaciers as compared to sulphate being twice larger than winter. The annual runoff increase (ARI) from the cumulative impact due to all aerosols showed the most significant ARI for Pindari glacier (about 500 mm w.e. y−1), with five out of the nine glaciers, including Sankalpa, Milam, Gangotri, and Chorabari, had an ARI exceeding 300 mm w.e. y−1. Analysis from source- and region-tagged simulations indicates about 50 to 60% of aerosols-induced ARI can be mitigated by controlling BC aerosols over the region originating from open-biomass burning emissions mainly in the Indo Gangetic plain (IGP) and far-off region.
How to cite: Verma, S.: Simulations of cumulative and relative impact of aerosol species over the Hindu Kush Himalayan region: validation, implications on glacier runoff, and source control, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1125, https://doi.org/10.5194/egusphere-egu25-1125, 2025.
The high yield of condensable vapors from OH-initiated oxidation of naphthalene raises intriguing questions about the role of ozone in this process. As the simplest polycyclic aromatic hydrocarbon (PAH), naphthalene is a significant component of anthropogenic volatile organic compounds (AVOCs) in urban atmospheres, characterized by its high reactivity and prevalence among PAHs. Emitted primarily through the incomplete combustion of fossil fuels and biomass, naphthalene plays a pivotal role in atmospheric chemistry under ambient conditions. While recent studies (Zhang et al., 2012; Garmash et al., 2020) highlight the substantial contribution of naphthalene to secondary organic aerosol (SOA) formation, these are in conflict with our current molecular level understanding of the oxidation process. In the atmosphere, naphthalene is quickly oxidized by the addition of an OH radical to the aromatic ring, forming a carbon-centered radical (Shiroudi et al., 2015, Gnanaprakasam et al., 2017). This subsequently reacts with O₂ to generate peroxy radicals, which undergo autoxidation, resulting in the formation of low-volatility products containing multiple oxygen atoms i.e., highly oxygenated organic molecules (HOM) which contribute to SOA formation. However, molecular level studies indicate autoxidation rates that are much too slow to explain the observed HOM in the oxidation of naphthalene. Also, previous experiments that measured HOM yields from OH-initiated oxidation of naphthalene (Molteni et al., 2018, Garmash et al., 2020) did not investigate the effect of ozone. We think that ozone is the missing piece in resolving the discrepancy between our current molecular level understanding of naphthalene oxidation and measurements.
In this study, laboratory experiments were conducted to investigate the oxidation of naphthalene by hydroxyl (OH) radicals using a flow reactor coupled with a nitrate-based chemical ionization mass spectrometer (NO₃⁻-CIMS). The influence of ozone on the reaction products was systematically explored. Results revealed a significant enhancement in product intensities, particularly monomers (C₁₀H₉O₅-₁₀), in the presence of ozone. The reaction time was varied from 2.1 – 0.7 seconds. At a reaction time of 0.7 seconds, the addition of ozone led to the formation of a series of monomeric products that were absent in the ozone-free environment. Complementary high-level quantum chemical calculations provided mechanistic insights into the role of ozone in product formation. To further elucidate product formation pathways, experiments were also conducted for the OH-initiated oxidation of naphthalene derivatives such as 1-naphthol and 2-naphthol. A significant effect of ozone was observed in the oxidation of 1-naphthol, whereas no prominent change was noted in the case of 2-naphthol. These findings indicate that the oxidation of naphthalene proceeds rapidly enough to compete with other bimolecular reactions such as RO2 + RO2/HO2/NO, and the presence of ozone is crucial for the formation of HOM and consequently has a pronounced effect on the SOA formation.
References:
Zhang, Z. et al (2012) Phys. Chem. Chem. Phys. 14, 2645 - 2650.
Garmash, O. et al (2020) Atmos. Chem. Phys. 20, 515-537.
Shiroudi, A. et al (2015) Phys. Chem. Chem. Phys. 17, 13719-13732.
Gnanaprakasam, M. et al (2017) Theor. Chem. Acc. 136, 131.
Molteni, U. et al (2018) Atmos. Chem. Phys. 18, 1909-1921.
How to cite: Kumar, A., Seal, P., Garmash, O., Ojala, A., Iyer, S., Barua, S., and Rissanen, M.: Role of ozone in enhancing the formation of aerosol precursors in the OH-initiated oxidation of naphthalene, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16516, https://doi.org/10.5194/egusphere-egu25-16516, 2025.
Black carbon (BC) is the most absorbing atmospheric aerosol and, therefore, influences the Earth’s climate system. Uncertainties in BC climate forcing estimates can be attributed to a limited understanding of its size distribution, mixing state, morphology, spatiotemporal distribution, and optical properties, all of which require more representative and long-term measurements (Bond et al., 2013; Liu et al., 2020). To investigate the long-term variation of BC physical properties, continuous measurements were conducted at the central European rural background site Melpitz (Germany) from August 2021 to February 2022. Mass concentrations, size distributions, and mixing state of BC were measured by a Single Particle Soot Photometer (SP2). A thermodenuder (300⁰C) was connected upstream of the SP2 to remove the volatile coating of BC. In addition, the light absorption coefficients were measured using a multi-angle absorption photometer (MAAP).
Different air masses associated with distinct refractory black carbon (rBC) properties were identified in summer (August) and winter (December). In summer, rBC exhibited a similar mass concentration (~0.16 μg m-3) among different air masses, with the smallest mass median diameter (MMD) of rBC overserved in the long transportation from the northwest (140nm), while in winter, the highest concentration (1.23 μg m-3) and largest MMD (216 nm) were both observed in easterly air masses. Thickly coated rBC fractions increased during the daytime in summer, indicating that photochemical processes significantly influence the rBC mixing state. In winter, a higher fraction (27%) of thickly coated rBC in the cold air mass compared to the warm air masses (14%) suggests the contribution of residential heating emissions to the mixing state. Most rBC particles retained a low-volatile coating when passing the thermodenuder with a mass fraction of 58%. In summer, photochemical processes also contribute to the volatility of coating, showing a higher fraction of rBC particles containing low-volatile coatings during the daytime. In winter, low-volatile coatings showed no significant diurnal variation and were more dependent on ambient temperature. Therefore, the volatility of rBC coatings in winter is more influenced by emission sources, particularly residential heating, rather than atmospheric processes. The optical properties of rBC showed seasonal variations as well, which were caused by changes in size distribution and mixing state.
Bond, T. C., et al. (2013). "Bounding the role of black carbon in the climate system: A scientific assessment." Journal of Geophysical Research: Atmospheres 118(11): 5380-5552.
Liu, D., et al. (2020). "Lifecycle of light-absorbing carbonaceous aerosols in the atmosphere." npj Climate and Atmospheric Science 3(1).
How to cite: Yang, Y., Müller, T., Poulain, L., Romshoo, B., Atabakhsh, S., Holanda, B. A., Voigtländer, J., Arora, S., and Pöhlker, M. L.: Seasonal characteristics in physical properties of refractory black carbon aerosols at a central European background site Melpitz, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11582, https://doi.org/10.5194/egusphere-egu25-11582, 2025.
Sub-micron aerosols are primarily consisted of organics, sulfate, nitrate, ammonium etc. and among which organics have high complexity in its chemical and physical characteristics. In the present study, aerosol volatility of non-refractory sub-micron aerosol was extensively studied during 6th – 20th February of 2021 utilizing high-resolution Time of flight Aerosol Mass Spectrometer (HR-TOF AMS) coupled with Thermal denuder. The temperature was set to 150oC and the denuded and non-denuded ambient aerosol was then sampled utilizing a switching valve with 10 minute time interval. Nitrate and Ammonium possessed highest volatility (80% and 68%) which was followed by organics with volatility rate of 54%. Sulfate was observed to be the least volatile (26%).The volatility extent for organics was low in afternoon and night-early morning hours due to possible prevalence of oxygenated organic aerosols (secondary organic aerosol) during these time period. Further PMF was done on the denuded and non-denuded organics aerosol dataset and the analysis revealed 4 factors namely, Hydrocarbon like organic aerosol (HOA), Biomass burning organic aerosol (BBOA), semi-volatile oxygenated organic aerosol (SVOOA) and low-volatile oxygenated organic aerosol (LV-OOA). LV-OOA fractional contribution increased from 31% to 56% of total organics. SVOOA, HOA, BBOA being a primary aerosol, showed decreasing trend as they have higher volatility than LVOOA. Interestingly, of SV-OOA volatility was even higher than that of the other primary aerosols (HOA, BBOA). The possible reason may be SV-OOA is freshly formed and can be deposited on to pre-existing aerosols like inorganic aerosols, HOA, BBOA, LV-OOA etc which indicated the effect of possible coating.
How to cite: Mukherjee, S., Patil, R. D., Yusuf, A., Meena, G. S., Vasudevan, A. K., Mahajan, A. S., Tinel, L., Waghmare, V., Patil, S. S., and Govindan, P.: Aerosol volatility over High-Altitude site in Western Ghats, India: Effect of semi-volatile organics coating, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18161, https://doi.org/10.5194/egusphere-egu25-18161, 2025.
Understanding aerosol properties and their life cycle in regional air masses is essential for assessing their impacts on clouds, precipitation and climate. High-altitude mountain stations, often emphasized as free-tropospheric measurement sites, are ideal for cloud and climate research. However, depending on the season and time of day, high-altitude sites may be influenced by planetary boundary layer (PBL) air masses due to convective transport. The segregation between PBL-influenced and free-tropospheric (FT) air masses remains a challenging but critical issue. Being able to unravel the periods for which clouds are influenced by each air type can vastly expands the scientific value and relevance of aerosol-cloud studies at mountain tops because cloud formation and their susceptibility to aerosol and dynamic perturbations vary considerably with each air mass type; the types of droplets and ice nucleators also can vary significantly, which further expands the scope and relevance of the measurements.
The Helmos Hellenic Atmospheric Aerosol and Climate Change ((HAC)²) station in Greece (2314 m a.s.l.) is the only high-altitude station in the eastern Mediterranean, a region highly sensitive to climate change. It is located at the crossroads of different air masses; the station is well-suited for aerosol-cloud interaction studies. To enhance understanding of the processes driving the formation and evolution of warm and mixed-phase clouds, the CALISHTO (Cloud-Aerosol InteractionS in the Helmos Background TropOsphere) and CHOPIN (Cleancloud Helmos OrograPhic sIte experiment) campaigns were conducted at Mount Helmos during the autumn-winter periods of 2021–2022 and 2024–2025, respectively. During these campaigns, in-situ and remote sensing measurements at a number of sites located at the Kalavrita Ski Center and the (HAC)2 were used to study the influence of the mixing layer (PBL), and their related aerosol and gases, at (HAC)². To achieve this, both in-situ and remote sensing instruments were employed. The permanent instrumentation of the (HAC)² station (e.g., GHGs, aerosol number size distributions, aerosol optical properties, meteorological data, and liquid water content) was supplemented with additional in-situ and remote sensing instruments operated at (HAC)² and the lower-altitude sites (about 1700 m a.s.l.). During the CHOPIN campaign, radiosonde measurements were conducted to measure critical atmospheric variables and provide further details about the structure of the atmospheric layers.
A set of aerosol and gaseous species and atmospheric metrics from in-situ measurements was established to indicate the presence of PBL air at the (HAC)² based on characteristic values of the water vapor mixing ratio, the accumulation mode (particles with a diameter greater than 95 nm) number concentration, and the ratio of eBC to CO. These thresholds were established by monitoring their values when the BL-FT boundary was at the (HAC)2 altitude, determined by remote sensing of atmospheric turbulence measurements. Application of these metrics to determine the presence (or not) of BL-influenced air agreed with the classification achieved by the remote sensing observations for up to 85 % of the time. Cloudy periods were studied separately from clear-sky periods owing to the substantially different gas and particle removal mechanisms occurring in each period.
How to cite: Gini, M., Zografou, O., Fetfatzis, P., Granakis, K., Foskinis, R., Mitsios, C., Molina, C., Jönsson, A., Zieger, P., Komppula, M., Papayannis, A., Nenes, A., and Eleftheriadis, K.: Evaluation of in-situ metrics for determining the influence of the Planetary Boundary Layer at the Helmos Hellenic Atmospheric Aerosol & Climate Change (HAC)2 station , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18522, https://doi.org/10.5194/egusphere-egu25-18522, 2025.
In this study, the observation site Himalayan Cloud Observatory is located at the high-altitude location (30.34 N, 78.40 E, 1706 m above mean sea level) and established at Swami Ram Tirth Campus, Badshahithaul, Tehri Garhwal, Uttarakhand in the western Himalaya. We have identified and characterized the new particle formation events for 12-months period (January to December, 2021) of continuous monitoring of the aerosol size distribution using NanoScan Scanning Mobility Particle Sizer. Another year-long observation was carried out at the Himalayan Atmospheric and Space Physics Research Laboratory (HASPRL), Department of Physics, Hemvati Nandan Bahuguna Garhwal University (A Central University), Srinagar Garhwal, Uttarakhand, in the Alaknanda Valley (30°13'37.3"N, 78°48'14.2"E, 640 m AMSL), from January 1, 2023, to December 31, 2023.
We have observed 51 new particle formation events out of 278 days of observations having 14% frequency of new particle formation occurrence. New particle formation events were most frequent in March-April-May (pre-monsoon) and least frequent in June-July-August-September (monsoon). This trend is linked to high temperatures, strong solar radiation, and low relative humidity in pre-monsoon, which enhance the formation of low-volatility organic compounds, while in monsoon, wet scavenging reduces aerosol precursor gases. The seasonal mean of growth rate (GR11.5-27.4 nm), formation rate (J11.5), coagulation sink (CoagS11.5-27.4) and condensation sink (CSTOT, 11.5-154 nm) during the study period were 1.27±0.23 nm h-1, 0.12±0.08 cm-3 s-1, 2.92±1.65×10-5 s-1 and 9.91±3.13×10-3 s-1 respectively. Seasonal distributions show particles within 11.5–100 nm predominantly originate from secondary emissions, while particles 100–154 nm result from both direct and nucleated process, highlighting the seasonal sources of particles at Himalayan Cloud Observatory. A significant reduction (by 25%) found in incoming solar radiation on non-event days limits the oxidation of precursor gases, thereby inhibiting particle formation. Polar bivariate analysis reveals that winter airmasses, transported via mountain winds from the southwest and northeast, introduce mixed particle sizes. In contrast, the localized concentration of particles with elevated GR11.5-27.4 nm and J11.5 during pre-monsoon highlights the role of aerosol precursors, condensable vapors, and favorable meteorological conditions, emphasizing new particle formation as the dominant particle source. Comparison with prior cloud condensation nuclei study at Himalayan Cloud Observatory reveals that new particle formation significantly supplements cloud condensation nuclei production beyond primary emissions, especially in pre-monsoon. The satellite-based observation of sulfur dioxide and formaldehyde complement and support the condensable vapours during event days at Himalayan Cloud Observatory. At HASPRL, smaller-sized aerosol particles showed an increase in the morning, likely due to emissions from anthropogenic sources originating from the southwest. In the evening, larger-sized aerosol particles were observed to increase, possibly resulting from various human activities such as vehicular emissions, transportation of sand and stone, and other anthropogenic emissions from the southeast. At HCO, particle transport is likely influenced by movement from valley and forested regions, with air masses traveling from the southeast to the southwest.
In summary, this research offers fresh perspectives on the characterization of new particle formation events in the Himalayan region of Uttarakhand. These insights are crucial for comprehending secondary aerosol formation processes worldwide, particularly at the process level.
How to cite: Gautam, D. A. S. and Singh, K.: New Particle Formation and Growth of Climate-Relevant Aerosols at Two Key Himalayan Sites in Uttarakhand, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-635, https://doi.org/10.5194/egusphere-egu25-635, 2025.
Posters on site: Mon, 28 Apr, 14:00–15:45 | Hall X5
The study aimed to evaluate the burden of anthropogenically emitted pollutants over an ecologically sensitive region of Munnar in Western Ghats, and quantify a baseline for aerosol measurements for comparisons with highly polluted urban clusters in India. Pre-monsoon sampling of PM₁ aerosols was carried out at the NABHA (Natural Aerosol and Bioaerosol at High Altitude) laboratory (10.09°N, 77.07°E), located ~1600 m above sea level, approximately 90 km east of the Arabian Sea. The collected PM₁ particles were analysed for metals, carbonaceous fractions, inorganic species, and polycyclic aromatic hydrocarbons (PAHs) to identify potential pollution sources and evaluate the toxicity of the sampled airmasses.
The PM₁ concentrations at this ecologically sensitive site were notably elevated, with an average of 21.7 ± 5.5 µg/m³ for the sampling duration. The physio-chemical analysis revealed the composition consisting of approximately 8% crustal dust, 7% sea salt, 20% sulphate, 7% ammonium, 42% organic mass (OM), and 4% elemental carbon (EC). Surprisingly, PM-bound nitrates were below quantifiable levels, likely due to the region's high relative humidity (>80%) and frequent precipitation, which may have scavenged nitrate salts, given their high water-solubility. However, nitrogen in the form of ammonia (1.5 ± 0.9 µg/m3) and water-soluble nitrogen (2.4 ± 0.8 µg/m3) was abundant in PM1. The concentration of PM₁-bound USEPA priority PAHs was 98.1 ± 11.2 ng/m³. This included 2–3 ring PAHs at 41.5 ± 7.5 ng/m³ and 4–6 ring PAHs at 56.7 ± 7.2 ng/m³.
Both the PM1 mass concentration and chemical characterization showed significant contribution of anthropogenically derived aerosol mass burden. The elevated OC/EC ratio (~6.6), coupled with a high water-soluble organic carbon (WSOC) fraction (~0.8), suggests a significant contribution from biomass burning emissions and active combustion sources in the region during sampling duration. Emissions from tea processing factories, coupled with the unchecked growth of tourist vehicles, are significant contributors to the regional high levels of sulphate, EC, Zn, Mn, Cu, and heavy metals in the ambient air. The influx of marine aerosols from the Arabian Sea further amplifies the regional pollutant load, particularly sulphate concentrations, formed through the atmospheric oxidation of dimethyl sulphide released by oceanic phytoplankton. These marine air masses additionally carry ship emissions, as evidenced by the significant presence of Ni and V in the aerosol composition.
The insights gained from this data at a strategically important geographic location are pioneering and have the potential to make a significant contribution to the development of pollution control policies in ecologically sensitive and high-altitude areas. Additionally, these findings could serve as a valuable resource for advancing climate change research.
How to cite: Gupta, A. D., Gupta, T., Gunthe, S. S., and Singh, A.: Characteristic aerosol properties from ecologically sensitive high-altitude region of Western Ghats in India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-561, https://doi.org/10.5194/egusphere-egu25-561, 2025.
The Montreal Protocol which mandated the global phase-out of ozone-depleting substances, contributed to the gradual recovery of Antarctic stratospheric ozone. Current projections estimate that the Antarctic ozone level recovers to the 1980 values by 2066. However, anomalous behaviours of the Antarctic ozone hole such as increased ozone hole area and prolonged ozone depletion have been observed since 2020. During this period, extreme events such as the Australian bushfires in 2020 and the Hunga Tonga–Hunga Haʻapai volcanic eruption in 2022 injected a significant amount of aerosols into the lower stratosphere. These aerosols provided the surface for chlorine activation reactions, contributing to chemical ozone loss in the polar lower stratosphere. Concurrently, previous studies suggest that the observed ozone depletion is also attributed to dynamic changes in the polar vortex and the descent of mesospheric air to the lower stratosphere. However, the relative percentage contribution of chemical and dynamical loss contributing to total ozone loss in recent years remains unquantified. In this study, we decompose the total ozone loss into chemical and dynamical losses using the passive tracer method, where ozone is considered as a passive tracer and simulated in the Chemical Lagrangian Model of the Stratosphere (CLaMS) using reanalysis data. The difference between the observed and simulated ozone provides information about the chemical ozone loss. These findings will help in advancing our understanding of the factors leading to the recent enhanced ozone depletion and the potential implications on the long-term healing of the ozone layer.
How to cite: Srinivasan, P., Kudilil, S., Narayana Sarma, A., Sreedharan K., S., and Krishnaswamy K, M.: Quantification of Chemical and Dynamical loss in Recent Antarctic Ozone depletion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-658, https://doi.org/10.5194/egusphere-egu25-658, 2025.
Entrance of metals in any form through any pathway causes significant damage to human health. The present study quantifies probabilistic health risk for carcinogenic and non-carcinogenic metals entering through inhalation, ingestion, and dermal routes within the human body for different age groups (children and adults). Water soluble metals (major metals; Na, Ca, K, Al, Mg, and trace metals; Fe, Zn, Sr, Ni, Cu, Mn, Cr, Ba, and Cd,) present into clouds over hilltop sites of the Western Ghats (Mahabaleshwar) and Eastern Himalayas (Darjeeling) situated at the entrance and final destination of monsoonal clouds over Indian Subcontinents are measured using ICP-OES. pH of cloud water is found to be alkaline in nature over both measurement sites. Clouds contain two times higher total soluble metal concentration (TMC) over Mahabaleshwar than that of Darjeeling. Analysis of enrichment factor and PCA suggest road dust, contributes maximum to the loading of metals into the clouds while desert dust coming from Arabian deserts contribute more to the initial clouds found in Western Ghats and fossil fuel influences maximum to the Himalayan clouds. Heavy metal pollution index (HPI) is found to be 14.8 over Mahabaleshwar and 22.6 over Darjeeling indicating relatively higher polluted clouds over Darjeeling due to higher concentrations of toxic metals like Cd and Zn emitted from fossil fuel combustion and road dust. Inhalation of polluted clouds containing higher concentrations of toxic metals like Cd, Cr, Mn, and Ni are the most potential threat to non-carcinogenic diseases. Cd is most dominating metal in clouds over Darjeeling, mainly coming from fossil fuel combustion, and has two folds higher HQ values than the Mahabaleshwar. Cr emitted from industrial waste has the highest carcinogenic health risk factor for children and adults over Mahabaleshwar (3.2×10-7, 2.3×10-7) than that of Darjeeling (2.1×10-7, 1.5×10-7). The present study suggests that clouds contain major metals like Na, Ca, Al, etc., mainly coming from marine sources and desert dust over the Arabian Sea and nearby continental regions while entering to Indian Sub-continental region, and later contaminated with trace metals like Cd, Cr, Cu, Ni, etc. emitted from vehicular emissions, industrial waste, and road dust that have greater impact on human health via inhalation pathway responsible for non-carcinogenic and carcinogenic diseases.
How to cite: Mushtaque, M. A., Saikh, S. R., Biswas, A., Darbha, G. K., and Das, S. K.: An Investigation on Source-Specific Health Risks Associated with Metals Present in Clouds over Hilly Regions in Indian Subcontinent, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1053, https://doi.org/10.5194/egusphere-egu25-1053, 2025.
Understanding aerosol particles in the Arctic is crucial due to their impact on the region’s radiative balance and their role in modifying cloud properties. These interactions drive unique feedback mechanisms that enhance Arctic warming and influence global climate systems. Consequently, it is important to identify and quantify Arctic aerosol particle sources and sinks, including their vertical transport, and to characterize their optical properties and resulting effects on cloud formation. Despite the importance of aerosol particles in the Arctic, there is a lack of direct measurements of aerosol particles over the Arctic especially over the Arctic marine boundary layer. In this context, we have conducted aerosol measurements aboard the German research vessel Polarstern during the ATWAICE (Atlantic Water Pathways to the Ice in the Nansen Basin and Fram Strait) expedition from June to August 2022. This study included continuous measurements of physical and chemical aerosol parameters to investigate variations in aerosol properties. On-line measurements of black carbon (BC) and its mixing state were complemented by off-line analyses of seawater and fog water samples to identify transport pathways of BC particles. Additionally, seawater, aerosol filter samples, and fog water samples were analyzed to explore how ice nucleating particles are linked across these compartments. Vertical profiles of aerosol particles were measured above different surface conditions to examine the direction of vertical particle transport. Higher aerosol concentrations were recorded as the ship passed through the outer margin of the marginal ice zone, where marine sources dominate, supported by evidence of significant photochemical ageing processes. The highest values of refractory black carbon (rBC) and light scattering coefficients were measured during the transact from northern Europe to the Arctic circle (between 56°N to 70°N), with average rBC concentrations of approximately 40 ng m-3 and light scattering at 525 nm averaging ~29 Mm-1. During this period, air mass trajectories reflected a nearly equal influence from both continental and marine sources. In contrast, the lowest scattering and absorption values were observed in the central Arctic, when the ship navigated in densely packed ice regions under the influence of north-easterly air masses originating over the Arctic Ocean. A comprehensive analysis of these findings will be presented in this presentation.
How to cite: Babu Suja, A., Müller, T., Pöhlker, M., Wex, H., Held, A., van Pinxteren, M., Yang, Y., Oehlke, P., Lüchtrath, S., Siebert, H., Mathes, T., Merkel, M., and Wehner, B.: Overview of Atmospheric Aerosol Observations during the ATWAICE Expedition in the Central Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7323, https://doi.org/10.5194/egusphere-egu25-7323, 2025.
Aerosol optical depth (AOD) observations are usually focused on the visible wavelength. Recent studies highlight the potential of the infrared emission waveband in providing valuable insights for aerosol compositions (Ji et al., 2023). Expanding AOD measurements into the infrared spectrum offers an approach to enhance our understanding of aerosol properties. In this study, we use solar absorption spectra measured by Fourier Transform Infrared Spectrometer (FTIR) to obtain the infrared spectrum AOD using Langley method (Barreto et al., 2020) in several stations, including Ny-Ålesund (Arctic), Bremen (mid-latitude), and Palau (tropics). Integrating FTIR and sun-photometer observations, we obtain AOD in visible and infrared spetrum regions. This work highlights the possibility of extending traditional AOD retrieval method in visible wavelengths to a broad spectrum range.
Reference:
Ji, D., Palm, M., Ritter, C., Richter, P., Sun, X., Buschmann, M., and Notholt, J.: Ground-based remote sensing of aerosol properties using high-resolution infrared emission and lidar observations in the High Arctic, Atmos. Meas. Tech., 16, 1865–1879, https://doi.org/10.5194/amt-16-1865-2023, 2023.
Barreto, África, Omaira Elena García, Matthias Schneider, Rosa Delia García, Frank Hase, Eliezer Sepúlveda, Antonio Fernando Almansa, Emilio Cuevas, and Thomas Blumenstock. 2020. "Spectral Aerosol Optical Depth Retrievals by Ground-Based Fourier Transform Infrared Spectrometry" Remote Sensing 12, no. 19: 3148. https://doi.org/10.3390/rs12193148
How to cite: Ji, D., Palm, M., Sun, X., and Notholt, J.: Expanding the Langley Calibration Method to Infrared Wavelengths: Modeling, Validation, and Applications, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9716, https://doi.org/10.5194/egusphere-egu25-9716, 2025.
Processes occurring over the oceans, including greenhouse gas (GHG) fluxes and cloud-aerosol interactions, are a major source of uncertainty in the present climate state and hence in estimating near-term warming. To reduce this uncertainty, more comprehensive and specific observations over the oceans are needed. Due to the limited supply of dedicated research vessels, platforms of opportunity are essential to fill these observational gaps. We discuss here the Ships of Opportunity for Atmospheric Research (SOAR) program, a science infrastructure program built in collaboration with OceansX. SOAR’s purpose is to expand atmospheric observations in under-observed oceanic regions, providing new measurements to existing climate observation programs that provide open data to the global community.
We present current pilot projects under SOAR. A GHG flask sampler from NOAA Global Monitoring Lab is deployed on the Maersk Kentucky, which is taking samples as the ship transits the tropical Pacific. Sensors from NASA’s Maritime Aerosol Network (AERONET MAN), are also deployed on two other Maersk vessels and a Smyril Line vessel, where volunteer sailors are collecting aerosol optical depth measurements that are now accessible on the AERONET/MAN webpage. Finally, in collaboration with NOAA Global Monitoring Laboratory, SilverLining is developing a version of the NOAA Federated Aerosol Network (NFAN) package for deployment on ships of opportunity. This effort includes integrating instruments into a system adapted to marine environments and validating it against the NFAN technical standards. This project serves as a proof of concept for including additional higher-complexity atmospheric instrumentation packages in ships of opportunity programs
How to cite: Lamarque, J.-F., Wong, A., Kaufman, S., Bowen, D., Schubert, S., Sweeney, C., Andrews, B., and van de Kraats, B.: Ships of Opportunity for Atmospheric Research: Pilot Efforts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11958, https://doi.org/10.5194/egusphere-egu25-11958, 2025.
Black carbon (BC) aerosols are a major concern in changing climatic scenario due to their ability to absorb solar radiation. This study investigates the temporal variation of BC and its impact on radiative forcing in the Sikkim Himalayan region. It aimed to understand the optical properties of BC and its radiative forcing at Yumthang Valley, a high-altitude (~3800 m) remote location in North Sikkim, India. In-situ measurements were undertaken to quantify BC mass concentration, using an Aethalometer, and satellite retrieval techniques were employed to assess the optical properties of BC during May 2022 to April 2024. The monthly mean BC concentration in the valley ranged from 1.03 ± 3.07 to 9.54 ± 16.44 µgm-3, with an annual mean of 5.07 ± 16.54 µgm-3. BC concentrations decrease during monsoon months due to limited long-range transport and effective wet scavenging. Biomass burning contributes significantly to BC levels, accounting for 88% of the total, with the highest contribution in September (55%) and the lowest in February (21%). Transport models indicate inputs from the Indo-Gangetic Plain and adjacent valleys with increased biomass burning activity. Seasonal variations reflect tourism-driven emissions and local wood burning, with the lowest levels observed in the early morning hours. BC-induced direct radiative forcing (DRF) was also calculated at the surface (SFC) and top of the atmosphere (TOA) using Santa Barbara DISORT Atmospheric Radiative Transfer (SBDART) model which estimate a substantial forcing at both the surface and top of the atmosphere. The BC-induced atmospheric heating rates suggest potential regional warming, which could accelerate glacier melt in the region.
How to cite: Gupta, A., Ranjan, R. K., Panicker, A., Anand, V., and Rajak, R.: Seasonal Dynamics and Radiative Impacts of Black Carbon in the Yumthang Valley in Sikkim Himalaya, India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12303, https://doi.org/10.5194/egusphere-egu25-12303, 2025.
Understanding the pathways through which aerosols are emitted, transformed, and removed in remote and climatically sensitive regions is essential for minimizing uncertainties in global climate modeling. This study capitalizes on the unique conditions created by the COVID-19 societal slowdown to explore anthropogenic aerosol behavior over South Asia. Observations during this period showed a marked decline in aerosol concentrations, resulting in a demasking effect comparable to nearly 75% of the radiative forcing induced by CO₂ in the region. Additionally, this reduction caused a ~7% increase in surface-reaching solar radiation and a ~0.4 K d⁻¹ decrease in atmospheric solar heating.
Black carbon (BC) aerosols were further analyzed using dual-isotope (Δ¹⁴C and δ¹³C) techniques at monitoring sites in the Maldives and Bangladesh. Findings revealed a significant decrease in fossil fuel-derived BC, dropping from 49% to 35%, while emissions from C₃ biomass burning rose from 31% to 55%. These changes reflect reduced fossil fuel usage alongside increased reliance on crop residue burning and biomass for domestic energy needs during the slowdown.
These findings highlight the complex interplay between human activities and natural processes in determining aerosol-climate interactions across South Asia. The rapid changes in emission patterns observed during societal disruptions underscore the potential for targeted policy interventions to mitigate climate impacts and reduce atmospheric pollution.
How to cite: Chandrika Rajendran Nair, H. R.: When the World Stopped: Insights into Aerosol masking effect and Black Carbon Source Shifts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12522, https://doi.org/10.5194/egusphere-egu25-12522, 2025.
Aerosol Black Carbon (BC) can influence Earth’s radiation balance and climate in numerous ways. Atmospheric warming and the modification of the local thermodynamic structure of the atmosphere, cloud formation and precipitation are known to be influenced by BC aerosols. Many of these effects depend on the vertical distribution of BC. When the concentration of absorbing aerosols such as BC are significant, Aerosol Optical Depth (AOD) and chemical composition are not the only determinants of aerosol radiative effects. Under such circumstances, the altitude of the aerosol layers also plays a crucial role. Thus, high BC loading at elevated altitudes is of utmost importance to regional weather and climate. These elevated aerosols can further be lofted to the upper troposphere and lower stratospheric regions through strong tropical monsoonal updrafts. Despite the above significances of elevated BC layers, measurements of the vertical distribution of BC in the middle and upper tropical troposphere are extremely scarce due to the difficulties in devising suitable instrumentation. Hence, direct measurements of BC are virtually non-existent at altitudes around 10 km or above. Under this backdrop, we conducted a series of high-altitude balloon observations to improve the understanding of such elevated layers. Results of these experiments conducted during the winter and pre-monsoon summer seasons of the years 2023-2024 show several elevated layers of BC aerosol, reaching as high as three times that of the surface concentrations. In the mid/upper troposphere, aircraft engine exhaust is the main if not the only source for anthropogenic emissions, with a technology trade-off existing between the fuel performance of engines, and climate forcers. The role of aircraft emissions in the mid-tropospheric region in contributing to these layers has also been examined in the background of balloon experiments.
How to cite: Sunilkumar, K., Ajay, A., Anand, N. S., Satheesh, S. K., and Krishna Moorthy, K.: Vertical profiles of black carbon measured using high-altitude balloon experiments over an urban location in India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14674, https://doi.org/10.5194/egusphere-egu25-14674, 2025.
The Antarctic region is a large component of the global climate system. While it is largely underrepresented in climate models due to the scarcity of in-situ data, the interactions between processes occurring mid- and high-latitude are even less investigated. Understanding the processes between the atmosphere, the ocean laying within the polar front is critical to assert the relevance of climate models and improve future climate predictions.
The SOPHYAC-light (Responses of the Southern Ocean PHYtoplankton to climate changes, feedback to the Atmosphere -impact of Light) took place onboard of the research vessel Marion Dufresne during the Obs’Austral campaign 2025 between December 24th 2024 and February 5th 2025. Air-sea interaction process studies were performed using two Air-Sea Interface Tanks (ASIT, Sellegri et al. 2023) in the aim of quantifying realistic air-sea fluxes and their relation to seawater biochemical properties, as well as the impact of UV light on these processes. The twotanks, one as a control and the other UV shielded, were filled with 1 m3 of seawater each at 7 different locations of the Southern Ocean, between sub-tropical and sub-Antarctic regions along the ship track. The incubation time varied between 4 and 6 days with coordinated water sample coupled with continuous atmospheric sampling within the head space of the two ASITS, with measurements of chemical, physical & biological parameters. The atmospheric measurements were focused on the investigation of new particle formation, encompassing three mass spectrometers for the characterization of gas phase precursors of aerosols and nanoparticle size distribution. A first overview of the SOPHYAC results related to new particle formation purely driven by the marine environment and ecosystem across the tropical / polar transect will be presented at the conference.
How to cite: Quéléver, L. L. J., Bahr, M., Rose, C., Bassez, M., Barthelmess, T., Dimier, C., Dulaquais, G., Eschalier, A., Fiel, H., Frère, W., Ingeniero, R., Néel, B., Raimbault, E., Ridame, C., Boyé, M., and Sellegri, K.: Investigating marine driven new particle formation during the SOPHYAC-light campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15052, https://doi.org/10.5194/egusphere-egu25-15052, 2025.
In this study, we present and analyze the first continuous time series of relevant aerosol precursor
vapors from the central Arctic (north of 80° N) during the Multidisciplinary drifting Observatory for the Study of
Arctic Climate (MOSAiC) expedition. These precursor vapors include sulfuric acid (SA), methanesulfonic acid
(MSA), and iodic acid (IA). We use FLEXPART simulations, inverse modeling, sulfur dioxide (SO2) mixing
ratios, and chlorophyll a (chl a) observations to interpret the seasonal variability in the vapor concentrations
and identify dominant sources. Our results show that both natural and anthropogenic sources are relevant for the
concentrations of SA in the Arctic, but anthropogenic sources associated with Arctic haze are the most prevalent.
MSA concentrations are an order of magnitude higher during polar day than during polar night due to seasonal
changes in biological activity. Peak MSA concentrations were observed in May, which corresponds with the
timing of the annual peak in chl a concentrations north of 75° N. IA concentrations exhibit two distinct peaks
during the year, namely a dominant peak in spring and a secondary peak in autumn, suggesting that seasonal IA
concentrations depend on both solar radiation and sea ice conditions. In general, the seasonal cycles of SA, MSA,
and IA in the central Arctic Ocean are related to sea ice conditions, and we expect that changes in the Arctic
environment will affect the concentrations of these vapors in the future. The magnitude of these changes and the
subsequent influence on aerosol processes remains uncertain, highlighting the need for continued observations
of these precursor vapors in the Arctic.
How to cite: Boyer, M., Aliaga, D., Quéléver, L., Bucci, S., Angot, H., Dada, L., Heutte, B., Beck, L., Duetsch, M., Stohl, A., Beck, I., Laurila, T., Sarnela, N., Thakur, R., Miljevic, B., Kulmala, M., Petäjä, T., Sipilä, M., Schmale, J., and Jokinen, T.: The annual cycle and sources of relevant aerosol precursor vapors in the central Arctic during the MOSAiC expedition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15303, https://doi.org/10.5194/egusphere-egu25-15303, 2025.
The dearth of measurements of Volatile Organic Compounds (VOCs) in the marine boundary layer have raised question on how the marine environment is impacted or can impact the overlying atmosphere. VOCs emissions in the interface between air and soil, snow or ocean plays a major role in atmospheric oxidation processes, gas-particle transfer and the formation of secondary organic aerosols. Recent studies indicate that some VOCs produce low volatility vapors through the process of autoxidation (Ehn et al., 2014). These low volatility vapors under atmospheric conditions may rapidly form highly oxygenated molecules (HOMs) which act as important precursor vapors leading to new particle formation (NPF). Extensive studies have been done for the terrestrial VOC fluxes and much less attention has been given to the marine emissions of VOCs (Yu and Li, 2021). Coastal NPF may lead to the formation of coastal/marine clouds, which affect many coastal ecosystem processes and the radiation budget globally. Some of the previous studies in coastal settings have identified biogenic emissions as the main driving factor for the NPF (O'Dowd et al., 2002). Every year extensive cyanobacterial blooms occur in the Baltic Sea region and Finnish water bodies, and these blooms could be a significant source of iodic acid, biogenic sulphuric acid and methane sulphonic acid, and possibly biogenic volatile organic compounds (BVOCs) (Thakur et al., 2022) yet no marine BVOC fluxes field studies have been reported so far from this sector.
To understand sea to air emission processes of BVOCs and their role in aerosol formation, we have set up a permanent atmospheric laboratory at the Tvärminne Zoological Station (TZS) on the Finnish coast of the Baltic Sea in 2022, under the project “CoastClim” (https://coastclim.org). The laboratory houses state of the art instrumentation to measure the gaseous composition and aerosol size distribution. The continuous measurement of Dimethyl sulphide (DMS) and monoterpenes at the coast, through proton transfer reaction-time of flight mass spectrometer (PTR-ToF-MS) suggests high emissions during the bloom period in summer (June-August 2023). A field experiment through floating glass chamber flux measurements over the algae and phytoplankton rich waters was also carried out at the coastal site of TZS station from 30th May 2022 to 8th June 2022. The samples were collected in Tenax tubes and analyzed using a thermal-desorption instrument connected to a gas chromatograph (Mäki et al., 2017) with a mass selective detector. The results showed high isoprene fluxes followed by a-pinene and other terpenes.
Further investigation on the source and processes of the biogenic VOC emission from the sea surface and oxidation chemistry happening in the air is needed to link these emissions to aerosol formation at the TZS coast. Connecting the coastal emissions to aerosol formation for understanding the impacts of climate change is one of the core aims of our multidisciplinary project “CoastClim”.
O’Dowd et al., 2002: doi:10.1038/nature00775
Ehn, M.et al., 2014 : https://www.nature.com/articles/nature13032
Mäki M.et al, 2017: https://doi.org/10.5194/bg-14-1055-2017.
Yu & Li., 2021: https://doi.org/10.1016/j.scitotenv.2021.145054
Thakur, R.C, et al., 2022: doi.org/10.5194/acp-22-6365-2022.
How to cite: Thakur, R., Peltola, M., Spence, K., Hellén, H., Tykkä, T., Norkko, J., Norkko, A., Kulmala, M., and Ehn, M.: Biogenic volatile organic compounds emissions from the coastal waters of Gulf of Finland, Baltic Sea and their role in aerosol formation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15525, https://doi.org/10.5194/egusphere-egu25-15525, 2025.
Atmospheric aerosols contribute to the largest uncertainty in estimates of the Earth’s global energy balance. Their interactions with sunlight and their ability to affect cloud formation leads to both direct and indirect influence of radiative forcing. The substantial uncertainties associated with aerosol climate effects stem amongst others from the complexity of their sources, composition, and properties. Aerosols in coastal areas present a challenging mix of inorganic and organic particles from diverse sources, making measurements and characterization of their properties in these regions essential.
This study presents measurements of the optical properties of ambient aerosols on Askö, Sweden, from October 2024 to January 2025. Askö, an island and nature reserve located approximately 80 km south of Stockholm, experiences low levels of local pollution, making it an ideal location for studying marine aerosols. Its location in the Trosa Archipelago, facing the Baltic Sea, also makes it well-suited for investigating the impact of long-range transport from Central and Eastern Europe.
Instruments were placed in a container situated on top of a floating platform near the island. Scattering coefficients, measured with a nephelometer, and absorption coefficients, measured with an aethalometer, were used to calculate Scattering and Absorption Ångström Exponents. The Ångström matrix was used to characterize aerosol types found in the area at different times. The optical data set is further complemented by local meteorological data, particle size distributions, and back trajectory analysis. This combination of data will give valuable insights into aerosol sources at this remote location, the degree of aerosol ageing, and the identification of prevailing emissions sources such as local emissions versus long-range transport of air masses.
How to cite: Tygesen Skønager, J., Salter, M., Bilde, M., and Rosati, B.: Relating aerosol optical properties to different emission sources at a coastal site in Sweden, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17907, https://doi.org/10.5194/egusphere-egu25-17907, 2025.
Posters virtual: Wed, 30 Apr, 14:00–15:45 | vPoster spot 5
EGU25-18095 | ECS | Posters virtual | VPS3
New Particle Formation and Condensable Vapours in an Arctic Site: Ny-ÅlesundWed, 30 Apr, 14:00–15:45 (CEST) | vP5.13
INTRODUCTION
New particle formation (NPF) is an important source of aerosol particles in the Arctic, the dynamics and drivers of which are still not fully understood. The concentrations of precursor gases, such as sulfuric acid (SA), methane sulfonic acid (MSA), iodic acid (IA), and highly oxygenated organic molecules (HOMs), are strongly linked with the occurrence and strength of NPF. Currently, though, measurement data of NPF, as well as precursor gases, in the Arctic remains extremely limited.
Here we present some preliminary results of our in-situ measurements deployed to study NPF in the Svalbard archipelago. The region is mapped by snow-, ice-, and permafrost-covered land, limited vegetation, and a strong marine influence of the sea ice. SA, MSA, and IA concentrations at the site are interlinked with the behaviour of ocean and sea ice. The terrestrial vegetation emits volatile organic compounds (VOC), which in the atmosphere convert to HOMs. As the Arctic is rapidly transforming due to climate change, all these ecosystems are being altered, which also affects the dynamics of NPF.
METHODS
The measurements considered in this work have been conducted at the Ny-Ålesund Research Station (Svalbard) and, originally started in 2017, represent the longest time series of aerosol data measured with mass spectrometry in the Arctic. In this work, the Arctic summer of 2024 is studied.
A nitrate-based chemical ionisation atmospheric pressure interface time-of-flight mass spectrometer (CI-APi-TOF, Tofwerk AG.) is used to measure precursor vapour concentrations and identify ion clusters in the ambient air. A neutral cluster and air ion spectrometer (NAIS, Airel Ltd) and a cluster ion counter (CIC, Airel Ltd) are used to monitor neutral particle (2-42nm) and ion cluster (0.8-42nm) size distribution. The measurements are paired with solar radiation data gathered at the Climate Change Tower by CNR (Mazzola et al., Rend. Fis. Acc. Lincei 27, 2016).
RESULTS AND DISCUSSION
A SA/MSA ratio larger than 1 was observed almost throughout the measurement period (Figure 1). This is contrary to previous results from the site by Beck et al. (Geophysical Research Letters 48, 2021). The difference could be due to yearly variation in the oceanic phytoplankton spring bloom, which affects atmospheric MSA concentrations Arctic.
From the preliminary analysis for one week, a diurnal cycle for SA and MSA was observed (Figure 2). NPF occurrence appeared to correlate with radiation intensity, as well as SA and MSA concentrations.
CONCLUSIONS
These preliminary results highlight the importance of long-term data sets in monitoring Arctic NPF, as they imply strong inter-annual variation in precursor gas concentrations, which may initiate NPF and growth of particles at the study site.
Figure 1. Daily mean values for precursor gas concentrations measured with CI-APi-TOF (May-August 2024).
Figure 2. Upper panel: 1.5-hour average values of net short-wave radiation and precursor gas concentrations from a seven-day period with NPF. Lower panel: particle size distribution measured with NAIS, from the same period.
How to cite: Vaittinen, A., Sarnela, N., Sipilä, M., Brasseur, Z., Boyer, M., Righi, C., Thakur, R., Mazzola, M., and Quéléver, L.: New Particle Formation and Condensable Vapours in an Arctic Site: Ny-Ålesund, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18095, https://doi.org/10.5194/egusphere-egu25-18095, 2025.
EGU25-1100 | ECS | Posters virtual | VPS3
Modulation of temporal evolution of black carbon aerosols at a rural location in the Western Ghats by meteorology and boundary layer dynamicsWed, 30 Apr, 14:00–15:45 (CEST) | vP5.44
Black carbon (BC) aerosols have been reported to influence the precipitation patterns over South-East Asia. In this study, we present surface measurements of BC carried out from a rural location in the Western Ghats and covering all the seasons. Despite being a remote location with negligible anthropogenic emissions, the total BC concentration is strongly modulated by particles originating from fossil fuel burning (~75%). Contrary to the prominent role played by boundary layer dynamics in the diurnal variations of BC in the tropics, our measurements reveal a disconnection between boundary layer dynamics and BC concentration mostly due to the advection from a distant urban location being the dominant source of BC. However, this influence is conspicuous on the concentration of particles originating from biomass burning. Seasonal variations in the wind fields, surface temperature, and rainfall are observed to influence the BC concentration, thereby leading to distinct diurnal variations seldom reported elsewhere. Reanalysis data sets fail to capture these changing patterns in BC, with daily mean concentrations exhibiting large differences with our observations (particularly in winter months) and diurnal patterns being different throughout the season. Under this backdrop, incorporation of these measurements could possibly improve the monsoon forecast in global climate models and provide deeper insights on the role of meteorology and boundary layer dynamics on aerosol fields in complex environments.
How to cite: Sunil S, D., Narayana Sarma, A., Kudilil, S., Sreedharan Krishnakumari, S., and Krishnaswamy, K.: Modulation of temporal evolution of black carbon aerosols at a rural location in the Western Ghats by meteorology and boundary layer dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1100, https://doi.org/10.5194/egusphere-egu25-1100, 2025.
