MOSAiC: onboard the largest Arctic expedition in history

It isn’t called the “largest Arctic expedition in History” for nothing. Last September 2019, the first group of researchers embarked on Leg 1 of the 1-year long expedition that will drift across the Arctic. In total, over 500 researchers from 20 countries are involved onboard and more behind the scenes for a project aimed at better understanding climate change in the Arctic.

At the Insititute for Atmospheric and Earth System Research (INAR) of the University of Helsinki, we have a group of 4 early career scientists who took or will take part in the Legs of the cruise: PhD students Lauriane Quéléver, Zoe Brasseur and Tiia Laurila, together with postdoc and campaing co-cordinator Tuija Jokinen.

Lauriane was the first to wave goodbye at the Norwegian coast and embark on the dark cruise for the following 3 months. This January she returned and has some news to share.

Photo: Lauriane Quéléver onboard Leg 1 of the MOSAiC expedition on the Polarstern research vessel.

What is the purpose of MOSAiC overall.
The Multidisciplinary drifting Observatory for the Study of arctic Climate (MOSAiC) expedition aims at understanding the arctic climate for better representation into the present climate model. In essence, the long-year observation of the atmosphere, biogeochemistry, ice, ocean, and ecosystem during the drift will provide the basis for projecting the arctic climate prediction.

What is INAR’s involvement in MOSAiC, different from other research groups?
INAR involvement in MOSAiC was coordinated with the Paul Scherrer Institute (PSI, Switzerland) in which we focused on understanding the interactions between the Arctic environment and aerosol processes which further impact the regional arctic climate. This involves better understanding of the sea – ice – atmosphere interactions and exchanges in two seasons: polar night and arctic summer. The collaboration between the two institutes enabled an impressive set of instruments that can measures the aerosol concentrations, composition and properties – from the smallest diameters (as small as 1 nm) to the climate relevant size of cloud condensation nuclei (CCN) – but also the trace gases potentially precursors of particles, all locally measured from a laboratory container placed at the bow of research vessel Polarstern.

What led to to the collaboration with PSI?
The project between INAR and the Paul Scherrer Institute (PSI) embrace interlinked research questions, while INAR focuses more on the Arctic new particle formation and its chemical processes, PSI aims at understand how aerosol impact the arctic climate. The experience from Julia Schmale’s group on doing atmospheric and aerosol science while cruising over the pole was essential for performing our measurement. PSI also provided the container infrastructure without which we could not measure otherwise. The collaboration provided a wider set of instruments from which both institutes are taking care during the expedition since we are sharing the manpower with one person only taking care of the whole instrumentation: Lauriane (INAR-Leg1), Ivo (PSI-Leg2), Julia (PSI-Leg3), Tiia (INAR-Leg4), Tuija (INAR-Leg5), Zoe (INAR-Leg6).

What training was involved for the INAR participants on the Legs?
Since only one person is send to take care of the whole PSI-INAR deployment, we set a battle plan with the future participant on board but also backup persons (in case plans changes). We are experts on different type of instrumentation, which is challenging, but it also becomes great for sharing knowledge. We organized training in Helsinki as early as a year ahead, and training at PSI while installing our instruments in the swiss container. Practicing the daily routine was a great help to feel more comfortable with an instrumentation that we were not use to run on daily basis before the start of MOSAiC.

Lauriane you are back, how was onboard research collaboration? Social activities?
Since we have only one person at a time from the INAR-PSI group, we set a SOS email where we communicated the status of the campaign more or less regularly, and most importantly when a problem occurs with the instruments (which could be fairly often 🙂 ). Of course, there is also many other (atmospheric) scientist that are experienced of the field and sometimes with similar instrumentation. On my side I had great help from the Atmos-team participant and from the crew, who did not hesitate to give a hand when I ran into trouble. On board, we had regular meetings: the ceremonial 18:30 daily science meeting and the dominical Atmos-team meeting. From time to time we also had some social event at the local bar, the ‘Zillertal’, where crew and scientist members gathered together to share some drinks and funny stories.

The first batch of data is back, what can you say preliminary about it?
The first leg was particularly challenging in order to get ‘clean’ data since, after finding the floe for the drift, an intense phase of set up occurred with several logistic event that can be source of contamination (e.g. refueling, helicopter flight, crane activity). These are inevitable when measuring in remote places. Beside contamination, we observed very interesting aerosol behavior between total aerosol concentration and ultrafine aerosol concentration when measuring in fog conditions. Additionally, the ice dynamics could generate lead opening from which chemicals (potentially aerosol precursors) were released into the atmosphere and possibly contribute to particle formation. So far, the analysis is very preliminary but our data are very promising.
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You can follow the day to day activities of MOSAiC documented via impressive photographs shared in their social media channels.

Photo credit: Lauriane Quéléver. Top: Onboard Polarstern research vessel. Middle: Lauriane Quéléver on MOSAiC Leg 1. Bottom: (left) inside INAR-PSI research container, (right) Polarstern vessel.

Interviewing Lauriane Quéléver and Tuija Jokinen, INAR/Univeristy of Helsinki, Interview text by Stephany Mazon, PEEX-HQ/INAR.

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