Small aerosol particles have a huge significance in the atmosphere. Without them, there would be no clouds, and the amount of water vapour, a powerful natural greenhouse gas, would be much more plentiful in the atmosphere. Our climate would be completely different.
In order to form a cloud, each droplet of water requires a particle to provide a surface for the vapour to condense upon. The creation of these particles begins with the formation of miniscule molecule clusters no more than a nanometre in diameter. These clusters are constantly created in the atmosphere through gas-to-particle conversion.
The clusters may grow as vapours, such as sulphuric acid, condense on their surface. After reaching a sufficient size, approximately 50 nanometres in diameter, they may serve as condensation nuclei for cloud droplets.
It has been estimated that globally, approximately one half of cloud condensation nuclei are created through this mechanism.
Creation mechanisms in nature only successfully measured and reported once
While the creation processes of particles have been studied for decades, they have only been examined with sufficient precision in laboratory conditions, in the CLOUD experiment at CERN. University of Helsinki researcher Mikko Sipilä, who recently received a two-million-euro grant from the ERC, has been actively involved in CLOUD since its inception.
The only study thus far capable of measuring the creation of particles directly from the atmosphere is also one of Sipilä’s.
Together with his research group, he observed the gas-to-particle conversion in an Atlantic coastal area in a study that was published in Nature in autumn 2016. They found that iodine compounds released by algae were converted into small particles through several processes.
However, there is currently no scientific evidence of the creation processes of particles in other areas of the world, and Sipilä and his group can now set about finding some, thanks to the ERC grant.
Small concentrations are a challenge
The most difficult aspect of the research is detecting the smallest clusters of just a handful of molecules and determining their chemical composition.
In the atmosphere, there may be just a few of such tiny clusters for each 1018 (billion billion) air molecules. This is a challenge for current measuring instruments. Consequently, the development of instruments has always been central to Sipilä’s research, which has led to two spin-out companies dedicated to measurement technology.
“If I could just buy the instruments I need from a store, this research problem would have been resolved ages ago.”
Measuring in extreme conditions
As Mikko Sipilä takes a global perspective towards his research, he cannot do his work in an office. He frequently packs up his laboratory and sets out on research trips around the world with his team.
The next destination is the Svalbard archipelago, where the researchers will spend six months studying particle formation in Arctic areas. Later this year, they will head to the Antarctic and the Southern Ocean. Plans are also underway for expeditions to the tropics, the Indian Ocean as well as mountainous areas to study the upper layers of the atmosphere.
Of course, Sipilä is also running constant measurements at the University of Helsinki’s SMEAR II station in Juupajoki. The laboratory experiments conducted under the CLOUD project in CERN add to his research.
Research in the polar regions is particularly demanding for the research group, as the conditions are very harsh. For this reason, members of the research team have received training which is typically not part of a physicist’s education. For example, they are trained in shooting (in case of polar bears), first aid and Spanish – a language Sipilä himself has also started to study.
“Some of my research destinations are in areas where English just isn’t a viable working language,” he says.
Results help understand human involvement in climate change
As aerosol particles are created both in nature and through human action, it is important that we understand both processes. By studying the atmosphere in the unpolluted Antarctic, researchers can uncover the natural mechanisms which generate particles in the Polar regions. By repeating the same studies in the Arctic region, which is exposed to sulphur dioxide and other pollutants due to the presence of shipping traffic and Siberian smelters, they can see how and to what extent human action disrupts nature’s mechanisms.
The intention is to ultimately feed the research results into computer models which describe the climate and predict its future.
“Since we don’t understand the mechanisms, we have been unable to reliably include them in climate models. I believe that our research will improve and expand our ability to understand human impact on the atmospheric system of the Earth,” states Mikko Sipilä.
The competitive ERC Starting Grant
In addition to Mikko Sipilä, University of Helsinki researchers who received the ERC Starting Grant in 2016 include Jing Tang, Samu Niskanen and Tuomas Tammela. The grant entails €1.5 million in funding for five years, with possible additional equipment funding.
Mikko Sipilä’s research group is part of Markku Kulmala’s Division of Atmospheric Sciences at the University of Helsinki’s Department of Physics. Kulmala recently received the honorary title of academician, the highest title that may be granted to a scholar in Finland.
Further information about the research can be found on the group website.
Please note! Mikko Sipilä will depart Finland for Svalbard on 15 March, 2017, and head to the Ny-Ålesund research village on 17 March, 2017. Ny-Ålesund is a radio silent research site, and there is no phone network. The research will also be documented here: https://npf-masspec-helsinki.tech.blog/blog/. =r follow @sipimikko.