Seasonal Sources of Biogenic Ice Nucleation Particles in the Arctic

TY - BOOK

T1 - Seasonal Sources of Biogenic Ice Nucleation Particles in the Arctic

AU - Jensen, Lasse Z.

PY - 2024/2/1

Y1 - 2024/2/1

N2 - The Arctic is particularly vulnerable to climate change, experiencing fasterwarming than the global average. This warming leads to multiple negativefeedback processes like sea ice decline and retreating glaciers due to lowerreflectivity and a warmer temperature. Another crucial factor in the Arcticclimate budget is the extent, lifetime, and properties of clouds. Clouds play acritical role in regulating the Arctic temperature by influencing heatdistribution and absorption, reflecting solar radiation, and trapping the heatemitted by the Earth in the form of infrared radiation. Cloud formations aremediated by aerosols, tiny particles suspended in the air. Aerosols, includingmineral dust and soot, serve as cloud condensation nuclei or ice nucleatingparticles (INPs) below -15 °C. Bioaerosols, encompassing bacteria, fungalspores, microalgae, cell fragments, and macromolecules, exhibit ice nucleationactivity (INA) at higher temperatures.A recent report by the Intergovernmental Panel on Climate Change hashighlighted the largest uncertainties in calculating effective radiative forcingchange as aerosol-cloud interactions. Other research suggests that thisuncertainty is primarily driven by the lack of understanding of sources,diversity, and activity of INA bioaerosols.In response to these research gaps this thesis addresses the uncertaintiessurrounding INA bioaerosols in the Arctic by examining their seasonal sources.Our findings reveal a distinct seasonality in the bacterial atmosphericcommunity, with long-range transport dominating bioaerosols during winterand early spring. In contrast, the summer period exhibits a shift to localsources. In winter, sea ice emerges as an overlooked source of biogenic INPs,while soil and streams play a crucial role as sources of highly active INPs in thesummer. These INPs can either be directly aerosolized into the atmosphere ortransported to the ocean, where melting sea ice and local productioncontribute to an enrichment of INPs in the surface microlayer, readily availablefor aerosolization during wave breaking and bubble bursting. Ourcomprehensive study significantly contributes to our understanding of Arcticmicrobial communities, their potential as producers of highly active INPs, andthe interactions influencing the distribution of these particles in air, soil, water, and ice environments. The significance of this research reaches intoconsiderations related to cloud formation, climate dynamics, and underscoresthe importance of addressing the impact of changing environmentalconditions on biogenic INP concentrations and emissions in the Arctic. Thisthesis establishes a solid foundation for future studies in this area.

AB - The Arctic is particularly vulnerable to climate change, experiencing fasterwarming than the global average. This warming leads to multiple negativefeedback processes like sea ice decline and retreating glaciers due to lowerreflectivity and a warmer temperature. Another crucial factor in the Arcticclimate budget is the extent, lifetime, and properties of clouds. Clouds play acritical role in regulating the Arctic temperature by influencing heatdistribution and absorption, reflecting solar radiation, and trapping the heatemitted by the Earth in the form of infrared radiation. Cloud formations aremediated by aerosols, tiny particles suspended in the air. Aerosols, includingmineral dust and soot, serve as cloud condensation nuclei or ice nucleatingparticles (INPs) below -15 °C. Bioaerosols, encompassing bacteria, fungalspores, microalgae, cell fragments, and macromolecules, exhibit ice nucleationactivity (INA) at higher temperatures.A recent report by the Intergovernmental Panel on Climate Change hashighlighted the largest uncertainties in calculating effective radiative forcingchange as aerosol-cloud interactions. Other research suggests that thisuncertainty is primarily driven by the lack of understanding of sources,diversity, and activity of INA bioaerosols.In response to these research gaps this thesis addresses the uncertaintiessurrounding INA bioaerosols in the Arctic by examining their seasonal sources.Our findings reveal a distinct seasonality in the bacterial atmosphericcommunity, with long-range transport dominating bioaerosols during winterand early spring. In contrast, the summer period exhibits a shift to localsources. In winter, sea ice emerges as an overlooked source of biogenic INPs,while soil and streams play a crucial role as sources of highly active INPs in thesummer. These INPs can either be directly aerosolized into the atmosphere ortransported to the ocean, where melting sea ice and local productioncontribute to an enrichment of INPs in the surface microlayer, readily availablefor aerosolization during wave breaking and bubble bursting. Ourcomprehensive study significantly contributes to our understanding of Arcticmicrobial communities, their potential as producers of highly active INPs, andthe interactions influencing the distribution of these particles in air, soil, water, and ice environments. The significance of this research reaches intoconsiderations related to cloud formation, climate dynamics, and underscoresthe importance of addressing the impact of changing environmentalconditions on biogenic INP concentrations and emissions in the Arctic. Thisthesis establishes a solid foundation for future studies in this area.

M3 - Ph.D. thesis

BT - Seasonal Sources of Biogenic Ice Nucleation Particles in the Arctic

PB - Aarhus University

CY - Aarhus

ER -