Aerosol processes in polar regions : from formation to climatic implications

Atmospheric aerosols affect our health, air quality, visibility and climate. They can impact the climate trough their ability to interact with radiation and to alter cloud properties by acting as cloud condensation nuclei (CCN) or ice nuclei (IN). Globally, aerosols cool the climate, but locally their effect may be opposite. Their climatic effects are determined by their concentration, size distribution and chemical composition as well as their vertical and spatial distribution and the underlying surface type. Currently, the largest uncertainties in estimating our future climate are related to atmospheric aerosols and their intearctions with climate. Polar regions are experiencing faster warming than the Earth on average. This enhanced warming leads to many dramatic changes in the cryosphere, including rapid shrinkage of Arctic summer sea ice. Arctic ampli cation also decreases the temperature gradient between the Arctic and polar air masses. Both of these changes feed back to the atmospheric dynamics and thus the transport of pollutants into the Arctic. The rapid climate change alters also the sources - both natural and anthropogenic - and sinks of secondary aerosols in polar regions. Therefore, it is crucial to understand the formation and growth mechanisms of atmospheric aerosols in these areas in order to assess their climatic effects. High latitudes also offer a great natural laboratory to study the aerosol dynamics and timescales for reaching climatically relevant sizes or obtaining a balance between sources and sinks, with very little anthropogenic influence. Moreover, as the precipitation amount and patterns will change in the future, the removal of aerosols is also subject to change. Quantifying this requires parameterization for climate models. This thesis adds to the understanding of all of these aforementioned parts in the aerosol processes and their climatic effects in polar regions. It offers the fi rst observations of Antarctic new particle formation (NPF) from continental biogenic precursors and shows that areas with melt water ponds over glaciers and continental ice sheets are important regions for the formation of secondary aerosols and the organics evaporating from such ponds have the potential to grow the particles up to climatically relevant sizes even in timescales of only few hours. In this thesis, it is also shown that in areas with low background aerosol concentrations, large sources of anthropogenic sulphur have a substantial impact to the trends in NPF and potential CCN in the scale of few hundreds of kilometers. This thesis also introduces a new way to study the evolution of aerosol number size distribution during air mass transport and shows that the aerosol condensational growth is markable even in the absence of evident NPF. Finally, this thesis offers the fi rst parameterization of snow scavenging in a way that is easily applicable to climate models.

Grantor dc:publisher

Helsingin yliopisto

Year dc:date.issued

2014

Author dc:creator

• Kyrö, Ella-Maria

• meteorologia

Statement dc:rights

• Julkaisu on tekijänoikeussäännösten alainen. Teosta voi lukea ja tulostaa henkilökohtaista käyttöä varten. Käyttö kaupallisiin tarkoituksiin on kielletty.
• This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
• Publikationen är skyddad av upphovsrätten. Den får läsas och skrivas ut för personligt bruk. Användning i kommersiellt syfte är förbjuden.

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10138/45329

OAI record oai:identifier

https://helda.helsinki.fi/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Ahelda.helsinki.fi%3A10138%2F45329