Kirsten N Fossum

• Doctor of Philosophy
• researcher at Ollscoil na Gaillimhe – University of Galway

Source apportionment quantitatively links pollution to its source but can be difficult to perform in areas like ports where emissions from shipping and other port-related activities are intrinsically linked. Here we present the analysis of aerosol chemical speciation monitor (ACSM) data using combined organic and sulfate ion positive matrix factori...

Organic aerosols play a significant role in atmospheric chemistry and climate, yet their sources and transformations remain poorly characterised over marine regions. This study aims at representing the clean Northeast Atlantic background by presenting the first source apportionment of organic aerosols (OA) at Mace Head, Ireland. Resolved organic ae...

Ultrafine secondary marine aerosol (<100 nm), formed via gas-to-particle conversion, can make an important contribution to the number of cloud condensation nuclei in the marine boundary layer. It has long been known that the growth of ultrafine secondary marine aerosol cannot be sustained solely by condensation of the inorganic species that drive t...

Source apportionment quantitatively links pollution to its source, but can be difficult to perform in areas like ports where emissions from ship and other port-related activities are intrinsically linked. Here we present the analysis of aerosol chemical speciation monitor (ACSM) data and combined organic and sulfate ion positive matrix factorizatio...

Organic aerosol (OA) is a key component to total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectr...

Sea spray aerosols (SSAs) make up a substantial proportion of aerosols in the global atmosphere and, especially when considering marine haze and cloud layers, can have a large impact on cloud formation and atmospheric radiative balance. Although SSA has the highest cloud condensation nuclei (CCN) activation potential, the majority of its population...

Approximately 80% of the Southern Hemisphere (SH) surface is oceanic, while the Northern Hemisphere (NH) hosts 85% of the world's population along with a broadly equivalent anthropogenic emissions contribution. Consequently, the so-called ‘background’ marine air loading would be expected to be notably lower, or cleaner, in the SH than that over the...

Organic aerosol (OA) is a key component to total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectr...

We present an aerosol cloud condensation nuclei (CCN) closure study over the north-east Atlantic Ocean using six approximating methods. The CCN number concentrations (NCCN) were measured at four discrete supersaturations (SSs; 0.25 %, 0.5 %, 0.75 % and 1.0 %). Concurrently, aerosol number size distribution, sub-saturation hygroscopic growth factor...

Five years of nearly continuous measurements of aerosol hygroscopicity by a Humidified Tandem Differential Mobility Analyzer (HTDMA) at Mace Head research station are presented, making it the longest aerosol hygroscopicity data set in marine environment and Northeast Atlantic region in particular. The main goal of this work was to examine seasonal...

We present an aerosol cloud condensation nuclei (CCN) closure study over the Northeast Atlantic Ocean using six approximating methods. The CCN number concentrations (NCCN) were measured at four discrete super-saturations (SS, 0.25, 0.5, 0.75 and 1.0 %). Concurrently, aerosol number size distribution, sub-saturation hygroscopic growth factor and bul...

Sulfate aerosols are typically the dominant source of cloud condensation nuclei (CCN) over remote oceans and their abundance is thought to be the dominating factor in determining oceanic cloud brightness. Their activation into cloud droplets depends on dynamics (i.e. vertical updrafts) and competition with other potential CCN sources for the conden...

Chemical composition and hygroscopicity closure of marine aerosol in high time resolution has not been achieved yet due to the difficulty involved in measuring the refractory sea-salt concentration in near-real time. In this study, attempts were made to achieve closure for marine aerosol based on a humidified tandem differential mobility analyser (...

Abstract. Chemical composition and hygroscopicity closure of marine aerosol in high time resolution has not been yet achieved because of the difficulty in measuring refractory sea-salt concentration in near-real time. In this study, attempts were made to achieve a closure for marine aerosol based on a humidified tandem differential mobility analyse...

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This work investigates marine aerosol physico-chemical properties (e.g. size and chemistry) and its Cloud Condensation Nuclei (CCN) properties under natural background conditions. Black carbon (BC), a tracer for anthropogenic pollution, was used to classify Southern Ocean air mass cleanliness, where the study focussed on anthropogenic influences an...

Atmospheric aerosols in clean remote oceanic regions contribute significantly to the global albedo through the formation of haze and cloud layers; however, the relative importance of 'primary' wind-produced sea-spray over secondary (gas-to-particle conversion) sulphate in forming marine clouds remains unclear. Here we report on marine aerosols (PM1...