Two ArcTrainees – one big scientific question: A story about leads from the MOSAiC drift expedition

168 days, that’s the time, we, Linda and Luisa, two ArcTrain students from Bremen, spent on our greatest scientific adventure so far: the MOSAiC drift expedition.

MOSAiC – The  Multidisciplinary drifting Observatory for the Study of Arctic Climate was a large, international research expedition. Frozen into the ice, the German research icebreaker Polarstern drifted with the sea ice for one year, and provided a research platform for hundreds of scientists studying the polar climate and ecosystem on a scale never seen before. One unique feature of this expedition was that year-long experiments were run continuously,  as scientists and crew were exchanged every two to three months.

Although the two of us were on two different legs and only met for a few hours during the handover, we are still sharing a common experience: being a MOSAiC scientist. 

What does this mean for us? MOSAiC is a great example of cooperation across disciplines, research interests, institutes, and legs! And since this idea of scientific cooperation fits so well with ArcTrain, we found our story worth telling you here on our blog.

Fig. 1: A lead forms when ice floes are moving away from each other driven by ocean currents and winds. Heat and moisture is exchanged between ocean and atmosphere, enhancing the formation of new ice (Credit: Luisa von Albedyll).

Our story is about leads. Leads are open water areas, cracks in the ice between the different ice floes (Fig. 1, 2). Leads play an important role in the Arctic. Since ice acts like a lid on the ocean, most of the heat and gas exchanges between the warm ocean and the cold atmosphere take place in the cracks of the lid: leads. During the Polar day, sunlight is absorbed by the dark ocean, while gases like CO2 or methane are exchanged. When it is below freezing, new ice is quickly forming in leads, a process that is faster the thinner the ice is. Leads are hotspots for the Arctic climate system, and that’s why they united all teams of MOSAiC, even across legs. Let’s take an example.

Luisa studies sea ice dynamics and deformation. Leads and pressure ridges are the visible signs of sea ice deformation that describe the relative motion of ice floes to each other. For example, leads are the result of divergent motion, i.e. when ice floes drift apart from each other (Fig. 1). During MOSAiC she observed sea ice deformation on the scale of hundreds of kilometers using radar satellites (You want to now more about satellites? Read a previous post about them here!), and on the scale of meters  using the ship-radar system. Using an airborne laser scanner and the EM-Bird, she monitored the presence of leads, the roughness of the ice surface, and the ice thickness.

Fig. 2: The mobile remote sensing instrument ‘Balamis Radiometer Ariel’ (L-band) measured thin ice at a lead (Credit: Linda Thielke).

Linda is working with images taken with a thermal infrared camera. Leads are an important aspect of her research because these areas are very efficient in exchanging heat between the ocean and the atmosphere. With the images taken from a helicopter, the spatial distribution of the open water and thin ice area is investigated on a local and regional scale. The variability of the heat flux, based on the sea ice characteristics, can be analysed on a satellite sub-footprint scale. During the expedition, we could measure sea ice properties we usually cannot see with the satellites because of their coarse spatial resolution (Fig. 2). This helps to improve satellite retrievals, which provide the only year-round Pan-Arctic observations, which represent an important source of data  about the changing climate.

Combining our research, we can compare the different estimates of the spatial distribution of leads. While Luisa focuses on the processes that create leads, Linda can measure their effects on heat transfer.

Those cross-cutting activities around leads were not restricted to work within a single team. Team Ocean measured turbulence of the upper ocean to understand the heat transport to the atmosphere. Team Atmosphere investigated the gas fluxes at the ocean-air interface; gases that the surprising variety of living species in the Arctic Ocean were producing and consuming. The chemical and physical conditions of their delicate ecosystem were the main focus of Team Eco and Team BioGeoChemistry.

MOSAiC as a big picture consisting of different puzzle pieces (Credit: Linda Thielke).

Combining our measurements with these of other disciplines helps us to draw the greater picture. It is just so much more exciting to have more than one piece of the puzzle when doing your own research. And MOSAiC offered us exactly this: the bigger picture!

This experience was also a great opportunity for us as early career scientists (ECS). We gained so much from the teamwork with international and experienced colleagues from several different fields, learned new things every day about our science and that of others; all while having a lot of fun.

Loving every day spent in the Arctic, going onto the ice motivated us for the physical work, the long working hours, and the challenges we faced. Nature was simply beautiful, and at times, challenging. We experienced storms, rain, fog, and breakups in the ice floe. We got wet feet, cold fingers, and were frustrated, but then we realized again how unique and fascinating this white world around us is.

You want to get even more insights into our time on the MOSAiC? On Twitter, we gave some insights on our experiences during the cruise, including some nice pictures!

You can find the whole thread here
You can find the whole thread here

The usual schedule of day during MOSAiC (Credit: Linda Thielke).
Scientific tasks during our field work
As part of the ICE Team, our goal was to capture the melt and refreezing of the sea ice. Therefore we supervised or joined different tasks:
> Set up, maintain and take down the remote sensing site with several instruments
> Conduct scienctific flights with the helicopter (EM-Bird, IR-Camera)
> Walk transect to measure ice and snow thickness, and ice properties
> Helping hands for: coring, snow pits, drilling, deploying buoys, ROV dives

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