Emissions of primary aerosols and aerosol precursors from the ocean are key for the Arctic climate. Among those, secondary aerosols from oceanic dimethylsulfide (DMS) are a key species for aerosol-radiation and aerosol-cloud interactions. However, the representation of DMS in atmospheric models is challenging, which generates large uncertainties in the Arctic aerosol budget. In this work we evaluate the sensitivity of simulated Arctic aerosols and clouds in the WRF-Chem atmospheric chemistry model, over a complete annual cycle, to (1) the representation of DMS chemistry in the atmosphere and (2) the oceanic DMS concentration product used as boundary condition. For (2), we compare the results obtained using the Lana et al. (2011) global climatology versus dedicated simulations of the Arctic Ocean biogeochemistry with NEMO-CSIB.
We find that aerosol number concentrations can change by up to more than 100%, including over sea ice, depending on the model configuration, with a greater sensitivity to the chemistry mechanism than to the oceanic DMS product. This change is negative in the summer, which leads to decreased cloud droplet number and increased (decreased, respectively) shortwave (longwave, respectively) radiation at the surface over sea ice. The opposite effect is found in late spring and autumn. Overall, we find that using a more complex chemistry and better description of Arctic Ocean DMS has an impact on the surface energy budget of +4 W/m2 on average for the year 2018, both over sea ice and the open ocean. This configuration also performs best compared to observations. Additional experiments evaluating the changes of aerosol number under future oceanic DMS concentrations, potential emissions of DMS through sea ice, and the role of methanesulfonic acid (MSA) nucleation in summertime aerosol number concentration are presented.
This work demonstrates the importance of accurately modeling DMS for simulations of the Arctic aerosol budget and climate, and the value-added of forcing atmospheric models with ocean biogeochemistry simulations.
How to cite: Lapere, R., Marelle, L., Haddon, A., Steiner, N., Raut, J.-C., and Thomas, J. L.: The importance of oceanic emissions for modelling Arctic aerosols and clouds, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5474, https://doi.org/10.5194/egusphere-egu25-5474, 2025.
Global climate models and reanalysis products have revealed large downwelling shortwave radiation biases over the Southern Ocean and Antarctica. The biases are hypothesized to be caused by the incapability of models to accurately simulate the frequent occurrence of low-level mixed-phase clouds in these regions. It’s crucial to elucidate the intricacy of cloud microphysics and aerosol-cloud interaction in climate models over the Southern Ocean and Antarctica in order to better simulate the climate system.
In this study, we use the ground-based observations colleted at Davis, East Antarctica to assess the capability of the high-resolution regional Unified Model (UM) to reproduce precipitating clouds off coastal Antarctica. We found the default configuration of the model can generally simulate the phase, vertical structure, and timing of clouds while exhibiting biases in the simulated water path and surface radiation fluxes compared to observations. A series of sensitivity tests with changed cloud and aerosol properties were conducted. The key findings suggest that: (1) Current monthly aerosol climatology implemented in the UM for cloud droplet activation largely underestimates aerosol concentrations, leading to fewer cloud droplets and worse radiation biases; (2) Increasing the cloud droplet number concentrations to a maximum satellite-based value doesn’t have a significant impact on liquid water path (LWP) and radiation biases; (3) A more realistic ice nucleating particle parameterization significantly increases the LWP and reduces temperature and radiation biases at coastal Antarctica. Moreover, preliminary results from coupling CASIM and GLOMAP aerosol schemes in the UM evaluated with ship-based observations over high-latitude Southern Ocean will be presented.
How to cite: Pei, Z., Fiddes, S., Mallet, M., Alexander, S., Furtado, K., Knight, C., Roff, G., Smith, D., Protat, A., McDonald, A., and French, J.: Simulating aerosol and cloud properties over coastal Antarctica in a high resolution regional model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-731, https://doi.org/10.5194/egusphere-egu25-731, 2025.
The Arctic is rapidly warming, causing reductions in sea ice extent and thickness. This is resulting in increasing areas of open water, which can act as a source of sea spray aerosol generated by bubble bursting at the sea surface. Changing local marine biogeochemistry is expected to have an increasing impact on the Arctic aerosol population. However, measurements of the Arctic atmosphere under these changing conditions are challenging and limited, especially during the fall-winter transition, when sea ice freeze-up is delayed. As such, there is little knowledge of how the changing ecosystem will influence the regional atmosphere and climate. To investigate Arctic sea spray aerosol particles during the fall-winter transition, we present measurements of individual particles collected during the November – December 2018 Aerosols in the Polar Utqiaġvik Night (APUN) field campaign in coastal Utqiaġvik, Alaska. The morphology and chemical composition of individual atmospheric particles ranging in diameter from 0.1–1.8 μm were measured using computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) and Raman microspectroscopy. CCSEM-EDX was used to identify individual sea salt aerosol particles and investigate their elemental composition, with an emphasis on quantifying organic carbon content. Using Raman microspectroscopy, we identified marine-derived organics within the individual sea salt aerosol particle coatings. The majority of the sea spray aerosol particles were identified as being produced from nearby open water, rather than being long-range transported. These measurements of sea spray aerosol during the coastal Arctic fall-winter transition will further our understanding of the connections between delayed sea ice freeze-up, seawater microbiology, and aerosol particle composition in the changing Arctic environment.
How to cite: Costa, E. J., Waters, C., Mirrielees, J. A., Kempf, H. E., Liu, J., Lee, J. Y., Holen, A. L., Wu, J., Ault, A. P., and Pratt, K. A.: Local Production of Arctic Sea Spray Aerosol in the Fall-Winter Transition, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-752, https://doi.org/10.5194/egusphere-egu25-752, 2025.
Field evidence has confirmed a new sea salt aerosol (SSA) source on sea ice, which may significantly affect polar boundary layer chemistry and polar winter climate. While the SSA production rate from blowing snow has been previously parameterised (Yang et al., 2008) and then validated by measurements at both Poles, some key parameters involved are not yet fully constrained, leading to uncertainties when using numerical models to compare with field measurements and assess their environmental and climate impacts. In this presentation, we focus on two key parameters: blowing snow size distribution and snow salinity, which determine SSA production in number and size, respectively. We aim to constrain these factors using the latest field data, supported by remote sensing BrO data and modelling. Blowing snow particles typically follow a two-parameter gamma distribution function with shape factor (alpha) and scaling factor (beta) varying over a large range. However, our recent work focusing on the Arctic Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition data showed that at a given height, beta values increase with wind speeds, while alpha gradually approach a constant value of 1.9 at higher wind speeds (e.g. larger than 10 m/s). This is the first time that we derive such a relationship for blowing snow, which further affirms the aerosol production mechanism from blowing snow and helps elucidate the underlying processes involved. Accordingly, we parameterised the blowing snow particle size distribution as a function of wind speed, accounting for variable wind speeds during storms. In addition, supported by a chemistry transport model (p-TOMCAT), we examined the sensitivities of SSA mass and reactive bromine release rate (in association with the SSA production) to representative snow salinities derived from observations in the central Arctic and coastal regions (at Eureka, Canada). Mean winter/springtime snow salinities that best represent the Arctic were derived by comparing the modelled BrO with ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) and air-based satellite-based GOME-2 BrO data at Svalbard and Eureka.
How to cite: Yang, X., Ranjithkumar, A., Frey, M., Eliza Duncan, E., Partridge, D., Lachlan-Cope, T., Gong, X., Nishimura, K., Strong, K., Criscitiello, A., Santos-Garcia, M., Bognar, K., Zhao, X., Fogal, P., Walker, K., Morris, S., Li, Q., Luo, Y., Zilker, B., and Richter, A.: Using Arctic field data and remote sensing BrO data to constrain blowing snow sea salt aerosol production parameterizations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10762, https://doi.org/10.5194/egusphere-egu25-10762, 2025.
Primary marine organic aerosol (PMOA) is a significant contributor to aerosol concentrations in remote oceanic regions, influencing aerosol-cloud-climate interactions. In the Arctic, sea ice retreat and summer ice loss are key drivers of potential increases in marine aerosol emissions. This study uses an extended version of the aerosol-climate model ECHAM6.3-HAM2.3 to investigate the emission patterns and trends of primary marine organic aerosol in the Arctic from 1990 to 2019 in large detail, considering changing climate and ice conditions. Using the offline results of the biogeochemistry model FESOM2.1-REcoM3, three aerosol-relevant biomolecule groups - polysaccharides (PCHO), amino acids (DCAA), and polar lipids (PL) - are modelled. Their atmospheric transfer is parameterized with OCEANFILMS, which was implemented into the aerosol-climate model ECHAM6.3-HAM2.3 to advance the marine emission scheme. Of the modelled organic groups, PCHO is most abundant in seawater, while PL dominates aerosol particles due to its higher air-seawater affinity. Seasonal variations in both the ocean and aerosol concentrations are pronounced, peaking between May and June, then gradually decreasing by late summer. The modelled PMOA seasonal patterns show reasonable agreement with ground-based measurements, considering the uncertainties in model assumptions and observations. Regional differences within the Arctic are evident in the initiation of biomolecule production in seawater and aerosol emissions. Long-term trends in Arctic PMOA emissions, analysed in this study, reveal a strong dependence on sea ice changes. Over the 30-year period, emissions have increased by at least 24%, with variations among biomolecules and regions. PCHO shows the most pronounced trend.
How to cite: Heinold, B., Leon-Marcos, A., van Pinxteren, M., Zeppenfeld, S., Zeising, M., and Bracher, A.: Emission patterns and trends of primary marine organic aerosol in the Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19566, https://doi.org/10.5194/egusphere-egu25-19566, 2025.
The Arctic region is undergoing rapid changes caused by a warming climate and positive radiative feedback loops associated with rapidly-declining sea ice. Clouds play a key role in melt onset timing and annual extent of sea ice loss by modifying the amount of radiation that reaches the surface. The characteristics of Arctic mixed-phase clouds, including lifetime and partitioning of cloud particle phase, are sensitive to ice nucleating particles (INPs), a cloud-active aerosol capable of initiating freezing of cloud droplets at temperatures above homogeneous freezing (-38 °C). INP concentration and freezing temperature (T) are necessary parameters for modeling and validating observations of cloud ice. Observations of INPs are therefore critical for reducing the uncertainties associated with aerosol-cloud interactions for predicting the future Arctic climate. We present an overview of temperature-resolved INP concentrations observed during the ARTofMELT (Atmospheric rivers and the onset of sea ice melt) expedition from May-June 2023. Included in this overview are concentrations of INPs from total aerosol filters (collected continuously on the icebreaker Oden and directly on the sea ice downwind of open leads) and from size-resolved aerosol collected on Oden. Information regarding particle size is pertinent for revealing the aerosol populations acting as INPs and, alongside back-trajectory and meteorological data, their sources. The concentration of INPs from the Oden total aerosol filters reached a maximum of ~1 L-1 at the coldest detectable temperature (-29 °C) and a minimum of ~0.0001 L-1 at temperatures near -10 °C. The total aerosol filters deployed on the ice were less effective at detecting the warm-temperature (rarest) INPs due to the shorter sampling periods. However, an INP maximum of ~1000 L-1 at T = -29 °C was reached on May 11 downwind of a lead, potentially due to wave breaking in strong winds. The total concentrations of INPs from the size-resolved samples were lower than the concentrations observed from both locations with total aerosol filters, likely due to the size cut-off in the size-resolved samples (0.34-12 μm in particle diameter). The variability in INP size distribution showed associations with wind speed and direction. At T = -20 °C, the largest size stage (2.96-12 μm) had the highest fraction of INPs during a period at the beginning of the expedition that encompassed a series of surface cyclones (May 11-18). The INP number concentrations in the smallest smallest size stage (0.15-0.34 μm) eclipsed those on the largest as a larger storm passed the Oden on May 13. Further analysis into INP size and composition, from heat and chemical treatments of samples, will be used to assess their sources.
How to cite: Mavis, C., Murto, S., Kojoj, J., Guy, H., Zieger, P., Brooks, I., Tjerström, M., Kreidenweis, S., and Creamean, J.: Evolution of the size and composition of ice nucleating particles within the synoptic context of the Arctic melt onset, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13063, https://doi.org/10.5194/egusphere-egu25-13063, 2025.
The rapid warming of the Arctic, driven by glacial and sea ice melt, poses significant challenges to Earth's climate, ecosystems, and economy. Recent evidence indicates that the snow-darkening effect (SDE), caused by black carbon (BC) deposition, plays a crucial role in accelerated warming. However, high-resolution simulations assessing the impacts from the properties of snowpack and land‒atmosphere interactions on the changes in the surface energy balance of the Arctic caused by BC remain scarce. This study integrates the Snow, Ice, Aerosol, and Radiation (SNICAR) model with a polar-optimized version of the Weather Research and Forecasting model (Polar-WRF) to evaluate the impacts of snow melting and land‒atmosphere interaction processes on the SDE due to BC deposition. The simulation results indicate that BC deposition can directly affect the surface energy balance by decreasing snow albedo and its corresponding radiative forcing (RF). On average, BC deposition at 50 ng g-1 causes a daily average RF of 1.6 W m-2 in offline simulations (without surface feedbacks) and 1.4 W m-2 in online simulations (with surface feedbacks). The reduction in snow albedo induced by BC is strongly dependent on snow depth, with a significant linear relationship observed when snow depth is shallow. In regions with deep snowpack, such as Greenland, BC deposition leads to a 25–41% greater SDE impact and a 19–40% increase in snowmelt than in areas with shallow snow. Snowmelt and land‒atmosphere interactions play significant roles in assessing changes in the surface energy balance caused by BC deposition based on a comparison of results from offline and online coupled simulations via Polar-WRF/Noah-MP and SNICAR. Offline simulations tend to overestimate SDE impacts by more than 50% because crucial surface feedback processes are excluded. This study underscores the importance of incorporating detailed physical processes in high-resolution models to improve our understanding of the role of the SDE in Arctic climate change.
How to cite: Zhang, Z., Zhou, L., and Zhang, M.: A numerical sensitivity study on the snow-darkening effect by black carbon deposition over the Arctic in spring, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2025, https://doi.org/10.5194/egusphere-egu25-2025, 2025.
Aerosol number size distributions, along with thermodynamic and dynamic parameters, were measured from the surface to 600 m using a tethered balloon, the Helikite. The field measurements were carried out at Villum Research Station in Northern Greenland from 23rd March to 2nd May 2024. During the transition from winter to spring, three types of atmospheric regimes were identified: (1) a background regime with a profile of uniformly distributed aerosols, represented by low particle number concentrations as well as number size distributions along the vertical axis similar to the surface number size distribution, (2) a winter-type regime characterized by a pollution layer observable at altitudes above 500 m and not observed at the surface, (3) new particle formation episodes in late April and beginning of May, which accompanied a warm airmass intrusion event that had trigged surface melt. Most of the profiles presented a temperature inversion below 200 m, and a low-level jet was sometimes visible between 50 m and 100 m. These recently acquired measurements helped to clarify when ground-based aerosol observations were representative for higher altitude aerosol populations. By capturing a warm airmass intrusion, a comparison could be established with previous events to better understand its impact on the Arctic climate.
Aerosol number size distributions from the Helikite ranged from 8 nm to 3 µm measured with a Miniaturized Scanning Electrical Mobility Sizer (mSEMS, Brechtel) and a Portable Optical Particle Spectrometer (POPS, Hendix). Wind speed and direction were obtained with a SmartTether (Anasphere), and temperature and relative humidity with SHT85 sensors (Sensirion). Observations from the Helikite were complemented by measurements from the Villum Research Station with a ceilometer (Vaisala CL51) for cloud heights, a Scanning Mobility Particle Sizer (SMPS, TSI) for surface aerosol number size distributions and a stand-alone condensation particle counter (CPC, TSI) for number closure, and a 9-meter meteorological mast (temperature, relative humidity, wind, shortwave radiation). Back trajectories from the Lagrangian Analysis Tool LAGRANTO were also used to shed light on the warm airmass intrusion event.
How to cite: Calmer, R., Favre, L., Dönmez, B., Dyson, J., Pohorsky, R., Jensen, B., Massling, A., Skov, H., Sørensen, L. L., Gryning, S.-E., Kumar, V., and Schmale, J.: Vertical measurements of aerosols in the high Arctic during the winter-spring transition using a tethered balloon. , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15432, https://doi.org/10.5194/egusphere-egu25-15432, 2025.
Biases of the winter near-surface temperature over Arctic sea ice have been reported in climate models, increasing uncertainties in future sea ice and Arctic climate projections. Mitigating these biases in future model versions requires proper evaluation and understanding of their origin. To progress on these matters, we focus on the near surface air temperature simulated in the atmosphere-only and coupled configurations of the IPSL-CM6A-LR climate model. To establish a reliable baseline for evaluating simulations, we identified a linear relationship between the mean surface air temperature from the European Centre for Medium-Range Weather Forecasts 5th generation reanalysis (ERA) and their bias relative to in situ observations from Soviet North Pole drifting stations. This relationship is then used to correct the ERA5 data. We find the winter near-surface temperature bias in the atmosphere-only IPSL-CM6A-LR configuration turns from cold to warm once ERA5 is linearly corrected, reaching +2.2°C over Arctic multiyear ice. The bias increases to +4.8°C in the fully-coupled configuration. Using a pan-Arctic energy budget evaluation, the warm bias in IPSL models is explained by an excessive poleward atmospheric heat transport. In the coupled configuration, the warm bias is increased by the too small sea ice extent, which also acts to reduce the overestimated atmospheric heat transport and leads to a too small poleward oceanic heat transport and surface energy budget. The methods developed here could be used in multi-model evaluations to further progress in understanding and reducing biases in climate models.
How to cite: Michalezyk, N., Gastineau, G., Vancoppenolle, M., and Rousset, C.: Evaluation and Attribution of a Warm Winter Bias Over Arctic Sea Ice in a Climate Model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3641, https://doi.org/10.5194/egusphere-egu25-3641, 2025.
Ongoing rapid changes in sea-ice cover require a more accurate representation of their interactions with marine biogeochemistry and cascading impacts on the global carbon cycle. Yet, despite the critical role of polar biogeochemical processes, assessing these interactions remains challenging as sea ice and snow are often treated as biogeochemically inert in most large-scale and climate models.
To address this gap, we present a novel integration of the Biogeochemical Flux Model in Sea Ice (BFMSI) within the three-dimensional global NEMO/SI3 system. This innovative coupling explicitly accounts for dynamic interactions between sea-ice physical properties and biogeochemical processes.
To evaluate this implementation, we perform two sensitivity experiments: one assuming a fixed biologically active layer in the sea ice and another where the thickness of this layer dynamically adjusts based on sea-ice permeability, as derived from the sea-ice model. Model results for 2000–2021 are compared against available observations, providing a brief performance assessment. The two experiments are also analyzed to evaluate the sensitivity of ice and under-ice biogeochemical properties to the biological active layer parameterization and the representation of the light transmission through the ice/snow.
These results aim to provide insights into the interplay between sea-ice properties and ocean biogeochemical processes, informing future studies on the role of sea-ice biogeochemistry in shaping the global carbon cycle and its response to ongoing climatic warming.
How to cite: Bachélery, M. L., Perez, I., Lovato, T., Tedesco, L., and Butenschön, M.: Towards Improved Polar Biogeochemistry: Integrating an Explicit Sea-Ice Biogeochemical Model in NEMO/SI3, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21585, https://doi.org/10.5194/egusphere-egu25-21585, 2025.
This study aims to assess the connectivity of currents around the Antarctic Peninsula and identify the structure of flows carrying particles from the Eastern to Western Antarctic Peninsula continental shelves. We use circulation data for the Weddell and Bellingshausen Seas from the “Whole Antarctica Ocean Model” to obtain and analyse particle trajectories using the “Probably A Really Computationally Efficient Lagrangian Simulator” (Parcels) model. In addition to the main Parcels kernels and a previously developed kernel that ensures the conservation of the number of particles during flow around irregularities in the bottom relief and the lower edge of ice shelves, we have also developed a kernel to simulate convection in the ocean upper mixed layer. Around 170,000 virtual particles were released at a depth of 10 m during a year with a spatial step of 1° in two shelf and slope sectors in the southern Weddell Sea where depth is less than 1500 m. The first sector covers a shelf area between 71°S and 77°S adjacent to the Filchner-Ronne Ice Shelf. The second sector covers a shelf area between 70°S and 65°S adjacent to the Larsen Ice Shelf. The pathways of water masses were characterised by the visitation frequency (the percentage of particles P that visit each 10×10 km grid column at least once in a modelling period of 20 years). The proportion of particles crossing 58°W (tip of the Antarctic Peninsula) is 21% of the total amount, while the proportion of particles turning northeast is 70%. The smaller sector, adjacent to the Larsen Ice Shelf, is the main source of particles transferred to the Bellingshausen Sea (51%). In contrast, particles released in the larger sector were mostly transported to the northeast (75%). Only 3.4% of the released particles were transported to the west of 80°W, while the Amundsen Sea (105°W) is reached only by 0.1% of released particles. This indicates a virtual lack of connectivity between the ocean circulation from the Weddell to the Amundsen Seas.
How to cite: Maderich, V., Bezhenar, R., Brovchenko, I., Boeira, D. F., Äijälä, C., and Uotila, P.: Lagrangian pathways connecting the Weddell and Bellingshausen Seas, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7289, https://doi.org/10.5194/egusphere-egu25-7289, 2025.
The Chemistry in the Arctic: Clouds, Halogens, and Aerosols (CHACHA) field project featured a wide collaboration from six universities to enhance the scientific understanding of multiphase halogen chemistry in the Arctic that took place in Utqiaġvik, Alaska during February-April 2022. This project was spurred by the pursuit of strengthening our understanding of how Arctic Sea ice loss and fossil fuel extraction affects atmospheric halogen chemistry.
In this study, cloud flights from the University of Wyoming King Air are evaluated closely to assess the ambient conditions relevant to the Arctic boundary layer during flights targeting clouds emanating from open leads in the Arctic sea ice. During these flights, the Particle into Liquid Sampler (PILS) was utilized using a Roger’s inlet and Counterflow Virtual Impactor (CVI) with low volume (1.5 mL) samples being collected. This study aims to introduce a methodological basis for prioritizing samples and identifying samples that can be safely grouped together to maximize the chemical analysis possible. Instruments are used for this method include Aerosol microphysics data from instruments including Condensation Particle Counters (CPC), Portable Optical Particle Spectrometer (POPS), and Passive Cavity Aerosol Spectrometer Probe (PCASP) and cloud microphysics data from a Cloud Droplet Probe (CDP) and Two-Dimensional Stereo (2D-S). Ultimately, this work is a key step in chemical analysis of cloud flights that will be used to better understand multiphase Arctic halogen chemistry by constraining a Lagrangian chemical box model and cloud parcel modeling.
How to cite: Lombardo, S., Selimovic, V., Lance, S., Woods, S., Jeong, D., Corral, A. F., Garner, N., Peterson, P., Costanza, C., Bigge, K., Starn, T., Stirm, B. H., Sorooshian, A., Fuentes, J. D., Simpson, W. R., Shepson, P. B., and Pratt, K.: Integrated Analysis of Airborne In-situ Cloud and Aerosol Microphysics Data during the 2022 Chemistry in the Arctic: Clouds, Halogens, and Aerosols (CHACHA) Field Campaign, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7504, https://doi.org/10.5194/egusphere-egu25-7504, 2025.
Recent case studies highlight that warm and moist air intrusion events are significant sources of aerosol particles in the Arctic, influencing cloud properties and thus the resulting radiative forcing in the region. However, the contribution of these short-lived events to different aerosol size modes, cloud condensation nuclei (CCN), and droplet number concentrations remains unconstrained. Here, we investigate the multi-annual aspects of intrusion impacts on aerosol properties using data on aerosol number size distributions, CCN, total particle number concentrations, and optical properties from multiple Arctic stations, including Alert, Tiksi, Utqiaġvik, Villum, and Zeppelin, covering the period 2010-2020.
Preliminary results suggest that particle concentrations change significantly during intrusion episodes, with variations across seasons and stations. For instance, contrary to previous studies, number size distribution data indicate a distinct decrease in accumulation mode concentrations during wintertime intrusion episodes relative to non-intrusion periods at several Arctic stations. In summer, this pattern reverses, although not uniformly across stations. Additionally, at Zeppelin, the average of the yearly mean CCN concentrations during intrusions is increased by 13% compared to non-intrusion periods, with some years showing increases exceeding 40%.
We explore the potential drivers of these observed number size distribution patterns and derive potential source contribution function and removal mechanisms along the trajectories, employing the Lagrangian analysis tool LAGRANTO.
How to cite: Dönmez, B., Pernov, J. B., Asmi, E., Chan, T., Krejci, R., Massling, A., Sharma, S., Skov, H., Tunved, P., Wiedensohler, A., Weinhold, K., Nenes, A., and Schmale, J.: Aerosol Number Concentration and Cloud Condensation Nuclei Variability During Warm and Moist Intrusions into the Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10952, https://doi.org/10.5194/egusphere-egu25-10952, 2025.
Surface albedo, sea ice growth and glacier mass balance in the Arctic are all heavily dependent on snow and thus also impacted by blowing snow through redistribution and increased sublimation. The sublimation of blowing snow is significantly higher than that of ground snow due to the larger surface area of the suspended snow crystals and the continuous entrainment of dry air. Thus, sublimation of blowing snow impacts the exchange of energy, moisture and particles between the snow and atmosphere in windy conditions.
Because of the difficulty of modelling such a small-scale process for large areas, parameterizations of sublimation of blowing snow are necessary for snow mass balance and aerosol production studies. The widely used Déry and Yau (2001) parameterization has only been evaluated with model data from the Canadian Prairie, but never for other surface types, where it is applied, or with in-situ observations. Therefore, the goal of this work is to evaluate the parameterization by Déry and Yau (2001) with observations from the MOSAiC expedition in the central Arctic and the Intensive Observation Period for Water (IOP4H20) field measurements in Ny-Ålesund, Svalbard.
Here we show observations of blowing snow events that were detected and characterized by a snow particle counter and the Video In-Situ Snowfall Sensor (VISSS). During these events, measurements of latent heat fluxes from eddy covariance systems are used to evaluate the parameterized sublimation rate. To address challenges with eddy covariance observations in snowy conditions and calculating column-integrated values the observations are complemented with the 1D-column PIEKTUK-D blowing snow model.
In this way, comparing the parameterization with observations brings insights into its uncertainty or possible limitations for two different surface types and thereby improves the estimation of the accuracy of snow mass balance and aerosol production studies that apply this parameterization.
How to cite: Monrad-Krohn, L., Maahn, M., Frey, M., and Déry, S. J.: Evaluating a Parameterization for Sublimation of Blowing Snow with In-situ Observations in the Arctic, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-614, https://doi.org/10.5194/egusphere-egu25-614, 2025.
Vertical profile measurements of aerosol properties in the lower atmosphere still constitute a major observational gap. Focusing on the polar regions, where the planetary boundary layer often forms temperature inversions that inhibit vertical mixing of the lowermost atmosphere, surface measure-ments can often not represent aerosol properties further aloft. However, understanding vertical aerosol distribution is critical for several reasons. From a climate perspective, in the Arctic and Antarctic, cloud formation is often sensitive to aerosol availability. Because clouds strongly influence the surface radiation budget and primarily exert warming, it is important to understand aerosols at cloud level.
Overall, understanding the thermodynamic structure of the lower atmosphere and the dynamics of vertical mixing is critical to answer questions on cloud formation. In situ measurements that describe the (thermo)dynamic, aerosol and cloud variables are indispensible to understand relevant process mechanisms and to improve models that typically struggle to simulate polar lower atmospheric aerosols.
Here we present results obtained with the Modular Multiplatform Compatible Air Measure-ment System (MoMuCAMS). MoMuCAMS can observe particle number size distributions (8-3000 nm) and overall concentrations, aerosol absorption, cloud droplet size distributions, and trace gas mixing ratios (CO2, CO, O3). Based on filter measurements, aerosol chemical composition and INP number concentrations can be obtained. Wind speed and direction, as well as temperature and relative humidity and video images are recorded.
We deployed MoMuCAMS up to 800 m with a payload of ~20 kg in Fairbanks, Alaska (Jan-Feb 2022), Pallas, Finland (Sep-Oct 2022), the Arctic Ocean (May-Jun 2023), southern Greenland (Jun-Aug 2023), and at Neumayer, Antarctica (Dec 2024 – Feb 2025). Overall, more than 350 profiles were flown. This contribution synthesizes observations of aerosol properties below, in and above clouds, and vertically resolved contributions of local and long-range transported particles.
How to cite: Schmale, J., Pohorsky, R., Lonardi, M., Temel, Y., Dyson, J., Calmer, R., and Favre, L.: From the Arctic to Antarctica: Observations of vertical aerosol distribution from tethered balloon measurements, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10134, https://doi.org/10.5194/egusphere-egu25-10134, 2025.
Surface Mass Balance (SMB) is a critical forcing of the long term contribution of the Antarctic Ice Sheet (AIS) to sea level. While most GCMs do not produce SMB as an output, several RCMs, including a new ensemble produced in the PolarRES project do and are used to provide forcing for ice sheet models. There are significant spatial variations between regional climate models forced with reanalysis. RCMs also inherit biases from forcing GCMs when run for historical and future climate pathways which may exacerbate or cancel out biases within the RCM. Since the previous intercomparison, there has been significant regional model development and an expansion of datasets that can be used for evaluating these. We assess the SMB estimates of downscaled GCM and reanalysis simulations over Antarctica, compared to a new updated observational database for the historical period. Our ensemble compares 19 SMB products, generated from 4 different GCMs downscaled by 6 RCMs and SMB models, to observations of SMB gathered in the 2024 SUMup dataset. As 8 datasets do not explicitly calculate SMB, we approximate SMB by subtracting evaporation and melt from precipitation with these models. The various simulations are all pan-Antarctic at resolutions from 11 to 27 km, and span periods from 24 to 64 years, between 1950 and 2023. Fidelity of models to observations varies from product to product. As would be expected given they assimilate observational data, reanalyses perform better overall, with minor biases, whereas climatological SMB from GCM-forced runs are usually too dry (5/9 GCM, 5/19 total). This is a significant bias in GCMs that will have an impact on modelled future evolution of the Antarctic Ice Sheet. One notable exception is the HIRHAM RCM forced by UKESM. In this case opposing biases appear to cancel out, giving the lowest t-statistic and one of the highest correlation coefficients in the intercomparison, while having the most comparison points due to the length of the simulation. The mean yearly accumulation of the models is 2100 Gt/year on the grounded AIS (Zwally’s mask) with most models predicting about 2000 Gt/year and 3 potential outliers predicting over 2500 Gt/year. Our analysis demonstrates that assessing model performance based on reanalysis driven simulations may provide misleading evidence of model performance for future projections. There are still large divergences in the spatial variability of modelled SMB. We also show the need for observational data with a wide spread in time and space.
How to cite: Cherblanc, C. and Mottram, R.: How well do downscaled Global Climate Models represent SMB in Antarctica?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12992, https://doi.org/10.5194/egusphere-egu25-12992, 2025.
The Korea Institute of Atmospheric Prediction Systems (KIAPS) is developing a spatio-temporal integrated coupled modeling system that is capable of forecasting from one week to two months. This system is based on the Korean Integrated Model (KIM) and incorporates the Nucleus for European Modelling of the Ocean (NEMO) framework to simulate ocean and sea ice components. While the coupled model’s mid-term prediction performance is comparable to that of the atmosphere-only model, it exhibits a significant cold bias in the polar regions when evaluated against reanalysis data such as ECMWF reanalysis version 5 (ERA5).
Polar regions, characterized by sea ice, present unique challenges due to the complex interactions between the atmosphere and the ocean. In winter, reduced sea ice formation allows more heat to transfer from the ocean to the atmosphere, further warming the air. Accurate simulation of these regions requires a further understanding of atmosphere-sea ice interaction. In this study, sensitivity tests of the atmosphere-sea ice exchange coefficient were conducted to optimize the momentum and heat transfer in the Arctic and Antarctic. The exchange coefficients were fixed at 0.0014 in the control run, while two parameterization methods, modulating sea ice roughness length, were applied to the experimental run. The results revealed opposing outcomes: one method caused atmospheric warming, while the other resulted in cooling, implying significant uncertainty in calculating the heat exchange coefficient. Further analysis of atmospheric and sea ice dynamics within the coupled KIM will determine the most suitable parameterization approach for accurate polar region simulations.
Acknowledgements. This work was carried out through the R&D project “Development of a NextGeneration Numerical Weather Prediction Model by the Korea Institute of Atmospheric Prediction Systems (KIAPS)”, funded by the Korea Meteorological Administration (KMA2020-02212).
How to cite: Jeong, J.-Y. and Koo, M.-S.: Effects of advanced atmosphere-sea ice exchange coefficient in the Korean Integrated Model (KIM) , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14691, https://doi.org/10.5194/egusphere-egu25-14691, 2025.
The Greenland Ice Sheet (GrIS) discharges ~1000 Gt yr-1 of freshwater into Arctic coastal oceans in the form of meltwater runoff and glacial discharge, with the majority entering the ocean via fjords. Fjordic ecosystems lie at the nexus of various facets of the environment, the ocean, land, cryosphere, atmosphere and biosphere, all of which are especially sensitive to climate change exacerbated by the rising global temperature. With the increase in length and intensity of the summer melt periods, both marine and land-terminating glaciers are slowly receding leaving altered downstream ecosystems in their wake. As glaciers recede, glacial outwash plains become exposed and the potential of sediment aerosolization increases. Concurrently, triggered by increasing melt-water discharge, marine biological productivity is changing, due to the evolving fjord dynamics, stratification, and composition. Hence, the composition and sources of atmospheric aerosols responsible for the cloud formation in this region are evolving and we expect this to influence both the Cloud Condensation Nuclei (CCN) and Ice Nucleating Particle (INP) populations. In addition to natural aerosols sources, also local anthropogenic activities can contribute to the CCN and INP populations. Furthermore, distant emissions e.g., from north American boreal forest fires, occasionally reach Greenlandic Fjord systems and can have significant impact on the aerosol properties.
In this presentation we aim to provide an overview of the processes which influence aerosol populations in Greenlandic fjord systems during Arctic summer. We will show results from a comprehensive and extensive field campaign in the Kujalleq province of Southern Greenland (60.91°N, 46.05°W) in June-August 2023. We will present aerosol size distributions, particle number concentrations, and scattering and absorption measurements from both ground-based and tethered-balloon measurement platforms. We will explore the following questions:
- What are the local and regional sources of aerosols leading to the formation of CCN in Southern Greenland?
- What is the current contribution of anthropogenic activities to the aerosol budget and how does this compare to the contribution from natural sources?
- How do long-range transport, new particle formation and ground-level fog events affect the concentration and vertical distribution of aerosols and subsequent CCN formation?
How to cite: Dyson, J., Bergner, N., Favre, L., Heutte, B., Surdu, M., Weng, J., Augugliaro, M., Winiger, P., Nenes, A., Violaki, K., Henning, S., and Schmale, J.: Exploring local and long-range aerosol source contributions to summertime CCN in Southern Greenlandic fjord systems, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16059, https://doi.org/10.5194/egusphere-egu25-16059, 2025.
Aerosol-cloud interactions remain one of the most significant challenges in accurately estimating human-induced radiative forcing, as well as projecting the future climate. To address this uncertainty, establishing the baseline levels of natural aerosols in various environments is crucial. The polar regions are ideal locations for studying natural aerosols due to their distances from anthropogenic influences, yet observations in these regions are relatively limited. Specifically, the role of oceans and sea ice in controlling aerosol concentrations, influencing cloud formation, and determining cloud phase remains unclear. A key component is biological aerosol particles that participate in the formation and microphysical modulation of Arctic mixed-phase clouds. Yet, many questions regarding their Arctic sources, emission processes, and ice nucleating properties remain.
We present a detailed study of potential natural sources of aerosols in the high Arctic over the pack ice during the ARTofMELT expedition (May–June 2023). We collected samples of snow, sea ice, seawater, and the sea-surface microlayer (SML) and utilized the comprehensive aerosol instrumentation setup on-board to analyze them immediately after collection for their chemical, microphysical, and fluorescent properties. After the expedition, further analysis of the samples was conducted including measurements of ice-nucleating properties and biological cell quantification.
Our results show that during the late Arctic spring, heightened biological activity in the seawater and the SML increased emissions of fluorescent primary biological aerosol particles (confirmed by increased cell count) and organic-coated sea salt particles. However, concentrations of ice-nucleating particles in liquid samples did not follow the same trend. We will present the clear distinctions found in the biological, chemical, and physical properties of all sample types, and the effect of salinity on the aerosolization process and ice nucleating activity. These results provide valuable information for future studies aimed at improving the source attribution of natural Arctic aerosols, helping to reduce uncertainties in their representation in models, and understanding their influence on Arctic mixed-phase clouds.
This work is currently in discussion at Freitas et al. (2024).
Freitas GP, Kojoj J, Mavis C, Creamean J, Mattsson F, Nilsson L, Schmidt JS, Adachi K, Šantl-Temkiv T, Ahlberg E, Mohr C. A comprehensive characterisation of natural aerosol sources in the high Arctic during the onset of sea ice melt. Faraday Discussions. 2024. DOI: 10.1039/D4FD00162A
How to cite: Kojoj, J., Pereira Freitas, G., Mavis, C., Creamean, J., Mattsson, F., Nilsson, L., Spicker Schmidt, J., Adachi, K., Santl-Temkiv, T., Ahlberg, E., Mohr, C., Riipinen, I., and Zieger, P.: Evaluating natural aerosol sources from the Arctic Ocean during the onset of sea ice melt, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17925, https://doi.org/10.5194/egusphere-egu25-17925, 2025.
Field studies in the high and mid latitudes have demonstrated that snowpack emissions of reactive trace gases driven by photolysis alter regional atmospheric composition, the fate of pollutants and the polar ice core archive of past environmental change. Of particular interest are reactive nitrogen and halogen species released by surface snow, which in turn influence atmospheric levels of O3 and hydroxyl radicals (OH and HO2). Previous field campaigns at South Pole and Dome C showed that surface-near air on the high East Antarctic Plateau in summer is highly oxidising due to the interplay of photolytic snow emissions, a shallow boundary layer and cold temperatures. However, open questions remain regarding the atmospheric oxidant budget above polar snow. Here we present recent observations carried out as part of the ISOL-ICE project at Kohnen Station (75ºS 0ºW) in austral summer 2017, located at a similar latitude as Dome C. Concurrent measurements of nitrogen oxides (NO and NO2), atmospheric particulate nitrate collected on filters, O3, slant-column bromine oxide (BrO), actinic flux and atmospheric turbulence were carried out for the first time at Kohnen. The bulk ion composition of in surface snow and shallow pits was measured as well.
While diurnal cycles of NOx and turbulent diffusivity were similar to previous observations at Dome C, a distinct and strong diurnal cycle of surface O3 with an amplitude of more than 10 nmol mol-1 was detected. O3 showed also a negative correlation with BrO in the lower atmosphere. These observations may imply O3 photochemical source/sink processes, which are stronger than seen previously on the East Antarctic Plateau. We discuss the role of O3 precursor emissions from the sunlit snowpack and vertical mixing with a view of the implications for our understanding of O3 above polar snow.
How to cite: Frey, M., Winton, H., Savarino, J., and Juranyi, Z.: Unusually strong diurnal variability of ozone (O3) above summer snow in East Antarctica – a discussion of pre-cursor snow emissions and atmospheric transport, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12209, https://doi.org/10.5194/egusphere-egu25-12209, 2025.
Stable boundary layers (SBL) commonly form during the Arctic polar night, but their correct representation has been posing major challenges for numerical weather prediction (NWP) systems. To enable innovative model verification, we performed measurements of the lower atmospheric boundary layer with airborne fiber-optic distributed sensing (FODS), a tethered sonde, and ground-based eddy-covariance measurements. Here we contrast findings across two representative synoptic forcings leading to structurally different inversion types in a fjord-valley system in Svalbard, namely inflow and outflow conditions during the arctic polar night in early 2024. The strong gradients of the inversions are accompanied by an increased temperature variance, which is related to enhanced buoyancy fluctuations. The observed vertical temperature and wind speed profiles are compared to two configurations of the HARMONIE-AROME system with different horizontal resolutions at 2.5 km and 0.5 km.
The higher-resolution model captures cold pool and low-level jet formation during weak synoptic forcing and valley outflow, resulting in a well-represented vertical temperature profile down to the snow surface, while the coarser model exhibits a warm bias in near-surface temperatures of up to 8 K due to underestimated inversion strength. During changing background flow to valley inflow conditions, the higher-resolution model is more sensitive to misrepresented fjord-scale wind directions and performs less well, while the coarser NWP system has a seemingly better agreement with the observations lending to the underrepresented interaction with the topography.
The results indicate the importance of the ratio between nominal horizontal model resolution and valley width to represent stable boundary layer features in a physically meaningful manner. Our results underline the substantial benefit of the innovative spatially resolving FODS measurements for model verification studies as well as the importance of model and topography resolution for accurate representation of stable boundary layers in complex terrain.
How to cite: Thomas, C., Mack, L., Kähnert, M., Jonassen, M., Batrak, Y., Remes, T., and Pirk, N.: Investigating Stable Boundary-Layer Temperature Profiles Observed from Fiber-Optic Distributed Sensing on a Tethered Balloon and comparing them against NWP Systems at Different Resolutions for an Arctic Fjord-Valley System in Svalbard, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7195, https://doi.org/10.5194/egusphere-egu25-7195, 2025.
Effusive volcanic eruptions are relatively gentle compared to explosive eruptions, resembling boiling stews rather than fireworks. They often last weeks, or even years, and can emit large amounts of gases into the lower atmosphere, among them sulphur dioxide. Through these emissions, they can impact climate via formation of sulphate aerosols and subsequent impacts on clouds. This was, for example, observed during the 2014-15 Holuhraun eruption in Iceland.
Volcanic eruptions with considerable effusive components have been common during the historical period in Iceland (the last ca. 1100 years), with roughly 20% of the more than 200 identified eruptions being either purely effusive or mixed effusive-explosive. The largest of those (e.g. 10th-century Eldgjá and 1783-84 Laki) occurred prior to the industrial revolution, when anthropogenic influences on the climate were smaller than they are today. As different atmospheric conditions modulate the cloud and climate responses to aerosol perturbations, a large pre-industrial effusive eruption might have different climate impacts were it to happen today or in the future. Here we use an Earth system model to simulate the surface climate response to an idealized Icelandic effusive volcanic eruptions, similar to 2014-15 Holuhraun, under pre-industrial (1850; PI), present day (2010; PD), and future (2090, SSP3-7.0; Ft) climate conditions and find that this is indeed the case.
The modulating effects of the climate state are especially prominent in the Arctic. During winter, we simulate stronger Arctic surface warming under PI conditions, compared to PD and Ft, as the background PI clouds are thinner and hence more transparent to longwave radiation. During summer, we find that the sea ice area significantly modulates the surface cooling in the Arctic, with more Arctic sea ice under PI conditions resulting in weaker surface cooling compared to PD and Ft conditions. We further model a significant increase in sea ice area, as a result of volcanic perturbations, during summer and fall across climate states through increased shortwave cloud shielding.
The different surface air temperature responses in the Arctic between different climate states are rather due to a warmer climate as a result of anthropogenic greenhouse gas emissions, with subsequent changes in cloud properties (during winter) and decreased sea ice (during summer), than changes in the background aerosol state.
How to cite: Zoëga, T., Storelvmo, T., and Krüger, K.: Arctic response to high-latitude effusive volcanic eruptions depends on the climate state, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12366, https://doi.org/10.5194/egusphere-egu25-12366, 2025.
Posters virtual: Thu, 1 May, 14:00–15:45 | vPoster spot 2
EGU25-12275 | ECS | Posters virtual | VPS29
Change in precipitation as a response to the Amundsen Sea Low characteristics in region of West AntarcticaThu, 01 May, 14:00–15:45 (CEST) | vP2.16
Climate change has led to the shrinkage of ice sheets and glaciers, contributing to sea level rise, particularly in regions like West Antarctica. Over the past several decades, this area has experienced one of the most pronounced increases in temperature and precipitation. Projections suggested increase in extreme precipitation by the end of the 21st century. Together with the expected deepening of the Amundsen Sea Low (ASL), these changes play a significant role in Antarctic ice sheet's mass in the future. This study aims to analyze a spatio-temporal precipitation variability and its extreme values in West Antarctica as a response to ASL characteristics. To analyze the relationships, we used a number of parameters describing ASL (average pressure field, the central pressure, the relative pressure at the center, longitude of the ASL, and the distance to the ASL center), and parameters for precipitation (daily totals and the 95th percentile) derived from the historical European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis data. The study is focused on natural zones along the coast corresponding to glacial basins such as Getz Ice Shelf, Thwaites Glacier, Pine Island glaciers, and Abbot Ice Shelf. Relationships between precipitation and ASL characteristics were assessed using Spearman rank correlation coefficients in each grid cell of the studied domain. Overall, the highest 95th percentile values, approximately 35 mm, were observed along the western coast of the Antarctic Peninsula. These values decreased to 15 mm along the remaining coastline of West Antarctica and further to 5 mm over the continental areas. Extreme precipitation had well-detected seasonality, with maximum precipitation totals during the austral autumn/spring seasons. In average, extreme precipitation events covered approximately 4.7–4.9% of basin areas. Over the last 30 years, the tendencies of extreme precipitation intensified the observed spatial differences: the 95th percentile increased over more humid areas with a trend of 4 mm/decade and decreased in continental regions by 2 mm/decade. The meridional position of ASL impacts weather and precipitation over the region much more than changes in its latitudinal remoteness to the coast. The ASL movement towards the west caused decreased precipitation near the Amundsen Sea and increased over the Antarctic Peninsula. Extreme precipitation was more sensitive to changes in ASL location than total precipitation. This study will contribute to understanding the occurrence of extreme precipitation events under climate change.
How to cite: Pysarenko, L. and Pishniak, D.: Change in precipitation as a response to the Amundsen Sea Low characteristics in region of West Antarctica, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12275, https://doi.org/10.5194/egusphere-egu25-12275, 2025.
