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MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate) Expedition

Background    Research Vessel     Expedition Status   References

Embark on the largest polar expedition in history: in September 2019, the German research icebreaker Polarstern has set sail from Tromsø, Norway, to spend a year drifting through the Arctic Ocean - trapped in ice. The goal of the MOSAiC expedition is to take the closest look ever at the Arctic as the epicenter of global warming and to gain fundamental insights that are key to better understand global climate change. 1)

Hundreds of researchers from 19 countries take part in this exceptional endeavor. Following in the footsteps of Fridtjof Nansen's ground-breaking expedition with his wooden sailing ship Fram in 1893-1896, the MOSAiC expedition will bring a modern research icebreaker close to the north pole for a full year including for the first time in polar winter. The data gathered will be used by scientists around the globe to take climate research to a completely new level. Led by atmospheric scientist Markus Rex, and co-led by Klaus Dethloff and Matthew Shupe, MOSAiC is spearheaded by Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI).

Understanding the consequences of Arctic climate change:

• MOSAiC will contribute to a quantum leap in our understanding of the coupled Arctic climate system and its representation in global climate models.

• The focus of MOSAiC lies on direct in-situ observations of the climate processes that couple the atmosphere, ocean, sea ice, biogeochemistry, and ecosystem.

An entire year trapped in the ice

The Norwegian researcher and explorer Fridtjof Nansen set sail on the first ever drift expedition 126 years ago with his wooden sailing ship Fram. But there has never been an expedition like the one now planned: for the first time, the MOSAiC project will take a modern research icebreaker laden with scientific instruments close to the North Pole in winter. 2)

The backbone of MOSAiC will be the year-round operation of RV Polarstern, drifting with the sea ice across the central Arctic during the years 2019 to 2020. During the set-up phase, RV Polarstern will enter the Siberian sector of the Arctic in thin sea ice conditions in late summer.

A distributed regional network of observational sites will be set up on the sea ice in an area of up to ~50 km distance from RV Polarstern. The ship and the surrounding network will drift with the natural ice drift across the polar cap towards the Atlantic, while the sea ice thickens during winter (red dotted line in Figure 1).

Large scale research facilities addressing key aspects of the coupled Arctic climate system will be set up on board of RV Polarstern and on the sea ice next to it, in the so-called ice camp.

The distributed regional network further around the central observatory will be comprised of autonomous and remotely-operated sensors, characterizing the heterogeneity of key processes in an area representing a typical grid box of modern climate models and providing invaluable data for the development of parametrizations for sub-grid-scale processes in climate models.

The German research aircrafts Polar 5 and Polar 6 will be operated to complement the measurements at the central MOSAiC site. A landing strip will be built especially for these research planes and for resupply flights in spring 2020.

Research and supply cruises by icebreakers from MOSAiC partners will provide support for the AWI research vessel Polarstern. They will further extend the geographical coverage of the observations and will link the measurements to the larger scales of the Arctic climate system and explore global feedbacks.

In addition, helicopters will be employed. Fuel depots for long-range helicopters have been set up on Bolshevik Island to broaden the spectrum of response options to potential emergency situations during the expedition.


Figure 1: Not only the science behind MOSAiC is a huge endeavor that needs the expertise of multiple nations and scientific disciplines, but also the logistics face unparalleled challenges (image credit: AWI).

The mission of MOSAiC 3)

MOSAiC aims at a breakthrough in understanding the Arctic climate system and in its representation in global climate models. MOSAiC will provide a more robust scientific basis for policy decisions on climate change mitigation and adaptation and for setting up a framework for managing Arctic development sustainably.

The Arctic is the key area of global climate change, with warming rates exceeding twice the global average (Figure 2) and warming during winter even larger. It is well possible that the Arctic ocean will become ice free in summer during the 21st century. This dramatic change strongly affects weather and climate on the whole northern hemisphere and fuels rapid economic development in the Arctic.

Future climate change projections for the Arctic are extremely uncertain with a factor of three uncertainty of projected warming by the end of this century – a much larger uncertainty than anywhere else on the planet (Figure 3).

Many processes in the Arctic climate system are poorly represented in climate models because they are not sufficiently understood. As long as we do not understand these processes, Arctic climate projections will not be robust.

The understanding of Arctic climate processes is limited by a dramatic lack of observations in the central Arctic, especially in winter and spring. During these seasons sea ice is so thick that even the best research icebreakers cannot penetrate into the Arctic and researchers have always been locked out.

The dramatic changes in the Arctic climate system and the fast retreat of Arctic sea ice strongly affect global climate. The inability of modern climate models to reproduce Arctic climate change is one of the most pressing problems in understanding and predicting global climate change.

MOSAiC sets out to investigate the heart of the Arctic climate system year-round – one of the largest uncharted areas in climate research.


Figure 2: Near surface temperature changes 1970-2017 (graphic credit: NASA GISS,


Figure 3: For the Arctic the uncertainties of climate models are much larger than for any other part of the planet. Here projections of the warming by the end of the century range between 5º and 15º Celsius among the different models, for the same rather pessimistic greenhouse gas emission scenario (RCP8.5) which is shown here (graphic credit: AWI)

Some background

• September 24, 2019: As millions of people around the world marched for urgent action on climate change ahead of this week’s UN Climate Action Summit, an icebreaker set sail from Norway to spend a year drifting in the Arctic sea ice. This extraordinary expedition is set to make a step change in climate science – and ESA is contributing with a range of experiments. 4)

With the youth calling for action, the climate crisis is in the public eye more than ever, and consequently there is more pressure to push the issue higher up the global political agenda.

The state of the climate has been detailed in a new landmark report that was produced for the summit. It says that the five-year period from 2014 to 2019 is the warmest on record and that sea-level rise has accelerated significantly over the same period as carbon dioxide emissions have hit new highs.

Needless to say, a better scientific understanding of the complexities of the fragile Arctic environment is critical for policy decisions on climate-change mitigation and adaptation, and for setting up a framework for managing Arctic development sustainably. The EU’s Integrated Policy for the Arctic includes a central pillar of climate change for this reason.

The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition is about to make a major contribution to Arctic climate science.

Spearheaded by the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI), it is the biggest shipborne polar expedition of all time and aims to take climate research to a completely new level.

It involves the Polarstern German research icebreaker spending a year trapped and drifting in the sea ice so that scientists from around the world can study the Arctic as the epicentre of global warming and gain fundamental insights that are key to better understand global climate change.


Figure 4: The MOSAiC expedition will make a major contribution to Arctic climate science. Spearheaded by the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI), it is the biggest polar expedition of all time. It involves the Polarstern German research icebreaker spending a year trapped in the sea ice so that scientists from around the world can study the Arctic as the epicentre of global warming and gain fundamental insights that are key to better understand global climate change – and ESA is contributing with a range of experiments (image credit: AWI, S. Hendricks , CC BY-SA 3.0 IGO)

During each phase of this huge international expedition, roughly one hundred people will be researching, working and living on board the icebreaker as well as on the sea ice. They will face some extremely harsh conditions during the polar winter – complete darkness, storms and temperatures that can drop to –40ºC.

Christian Haas, from AWI, said, “We want to better understand the processes and energy flows between the ocean, ice and atmosphere – and how they change over the course of the seasons.

We will also compare the data with satellite data, in particular with ESA’s CryoSat-2, which was specifically launched to measure ice thickness. This will allow us to observe how the ice grows and becomes thinner.”

ESA’s Tânia Casal said, “The MOSAiC expedition offers a unique opportunity to considerably improve our understanding of ocean–ice-snow–atmosphere processes and this will contribute to a more accurate modelling of future Arctic climate scenarios.

“We want to make sure that data associated with these processes delivered by ESA satellites and by the Copernicus Sentinels as well as from missions under development have the best possible impact. So we are contributing to the expedition with a range of calibration and validation activities.

“For example, as Dr Haas mentions that arrangements have been made for measurements to be taken that will be used to validate CryoSat-2, but also that validate the Copernicus Sentinel-1 radar mission.”

ESA’s Craig Donlon added, “We are currently working on new high-priority missions such as the Copernicus Imaging Microwave Radiometer (CIMR) mission and the Polar Ice and Snow Topography Altimeter (CRISTAL) mission to support the EU Integrated Policy for the Arctic. CIMR will provide high-resolution multispectral images of ocean, ice and snow properties and CRISTAL will provide estimates of sea-ice thickness. The two missions can work in perfect synergy.

“MOSAiC will give us an unprecedented time series of reference measurements to develop quality algorithms and data products from the CIMR and CRISTAL missions, which will support applications from weather forecasting to climate research, with benefit for the Copernicus services and beyond.”

Dr Casal noted, “In addition, we are working with the Japan Aerospace Exploration Agency (JAXA) to collect measurements from the ALOS-2 mission as part of our preparatory work on the ROSE-L mission, which is another high-priority candidate for Europe’s Copernicus program, and which will work in synergy with the Copernicus Sentinel-1 C-band radar for sea-ice charting services.”

ESA experiments also include ship-based instrumentation for dedicated validation measurements of the thickness of thin seasonal ice from the Earth Explorer SMOS mission.

Josef Aschbacher, Director of ESA's Earth Observation Programs, said, “The scale of MOSAiC expedition is truly remarkable and a testament to what international collaboration can achieve. Climate change is a very serious global concern, and the pioneering satellite missions we develop are key to measuring and understanding change so that informed decisions on action can be taken. This expedition gives us an important and unique opportunity to validate measurements being made from space as well as further the development of new missions on the drawing board. We wish everyone participating in MOSAiC the very best of luck – it will certainly be a challenging and harsh environment to work in.”


Figure 5: Sea-ice drift. In October 2019 the research icebreaker Polarstern will drop anchor at an ice floe in the northern Laptev Sea, which will mark the beginning of the MOSAiC experiment. The ship’s potential drift route can be roughly estimated in advance by reconstructing the course that the ice followed from the starting point in past years. This involves the use of satellite data, which depicts the ice drift in the Arctic on a daily basis. The image shows sample drift trajectories for 2005–17 and a potential starting point near 85ºN/130ºE. The starting date for the drift analysis is always 1 October of the respective year (image credit: AWI)

• September 20, 2019: During the MOSAiC expedition, researchers from the DLR Institute of Communications and Navigation will be measuring the disturbances of the Galileo and GPS navigation signals near the pole over a long period. “For this purpose, we have installed a high-rate receiver for navigation satellite data, one of our ‘in-house’ processors for measuring scintillations and a recording device for the raw data on board Polarstern,” says Simon Plass from the DLR Institute of Communications and Navigation. Scintillations are fluctuations of the electron density in Earth’s ionosphere. They influence the propagation of electromagnetic radiation; this includes the signals from navigation satellites. 5)

- Particularly in the vicinity of the north and south poles, the signals from navigation satellites are subject to disturbances caused by solar activity. No real data are currently available for the development of suitable countermeasures.

- DLR is closing this gap by collecting the necessary raw data from the Galileo and GPS systems in the Arctic Ocean during the one-year-long MOSAiC polar expedition. They will then be used to develop processing and correction algorithms.

- In the harsh environment of the Arctic Ocean, it is particularly important that position determination is always precise, and that safe navigation can be guaranteed.

The team of Simon Plass will operate the processor together with colleagues from the newly founded DLR Institute for Solar-Terrestrial Physics. “This is the first time that we will have acquired such extensive data from the north polar region. They represent a unique opportunity to compare the performance of different receivers under identical, controlled conditions and to develop new signal processing algorithms,” explains Plass.

The solar storm particles influence the functioning and accuracy of communications and navigation systems – particularly near Earth’s poles.

The explosive eruptions of charged particles from the surface of the Sun are referred to as solar flares. They are a cause of ‘space weather’ and the particles regularly interact with Earth’s magnetic field. The nearer one gets to the poles, the stronger the interactions become. Two of the best-known effects are the Aurora Borealis and the Aurora Australis, fascinating natural spectacles that make the influence of the Sun on the northern and southern polar regions visible to the human eye.

Charged particles from the Sun interact with Earth’s atmosphere and cause scintillations in the ionosphere. This interferes with radio signals on their way from satellites to the planet’s surface. Navigation signals in particular can be influenced to such an extent that precise positioning is sometimes no longer possible. In order to develop effective countermeasures, such as correction algorithms for navigation systems, satellite data from the polar regions are required. These data are currently not available.


Figure 6: Infographic: Charged particles from the Sun interact with Earth’s atmosphere and cause scintillations in the ionosphere. This interferes with radio signals on their way from satellites to the planet’s surface. Navigation signals in particular can be influenced to such an extent that precise positioning is sometimes no longer possible. In order to develop effective countermeasures, such as correction algorithms for navigation systems, satellite data from the polar regions are required. These data are currently not available (graphic credit: DLR (CC-BY 3.0))

Other DLR participants in the MOSAiC Arctic expedition: In addition to the Institute of Communications and Navigation, two other DLR facilities are taking part in MOSAiC. During the expedition, the German Remote Sensing Data Center (DFD) will be providing images derived from data acquired by the German TerraSAR-X radar mission in near-real time to support the complex expedition logistics in the sea ice. In addition to DFD’s own receiving stations in Neustrelitz and Inuvik, Canada, the Kongsberg Satellite Services (KSAT) station near Longyearbyen on Spitsbergen will also be used to receive data from the satellite. This station network is suitable for making the satellite data collected over the Arctic Ocean available to the researchers on board Polarstern as soon as possible after acquisition. The data are first transmitted from the receiving stations to Neustrelitz for processing and then delivered from there.

In addition to TerraSAR-X, other radar satellites will be used for MOSAiC, such as the Canadian RADARSAT-2 and the Japanese ALOS-2. The DLR Maritime Safety and Security Lab in Bremen will be responsible for the coordination of all the satellite images and the timing of further experiments or aircraft measurements. Together with the University of Bremen, it will also use the MOSAiC mission to improve the methodology developed at DLR for distinguishing between different types of ice and to derive further properties of snow and ice cover from satellite signals in the microwave frequency range. This research is part of a separate project, 'MOSAiCmicrowaveRS', funded by the German Research Foundation (DFG). In addition to the satellite data, it will use the extensive measurement facilities on the Polarstern.

RV (Research Vessel) Polarstern

For one year, she will be the center of the largest Arctic research expedition ever, spending a full annual cycle trapped in the massive Arctic ice: the Research Vessel Polarstern, flagship of Alfred Wegener Institute and icon of German as well as international Polar Research. 6)

Originally commissioned in 1982, the Polarstern is, to this day, still one of the most advanced and versatile polar research ships worldwide. Between 1999 and 2001, the ship was completely overhauled and now carries the latest equipment and technologies available. This is why she usually operates 317 days on average every year. Covering about 50,000 nautical miles per year, Polarstern carries out scientific research as well as resupplies the research stations run by the AWI (Alfred Wegener Institute) - such as the Neumayer Station III, an Antarctic base manned year-round. Until 2019, Polarstern has logged more than 1.7 million nautical miles, which equates to roughly 3.2 million km.


Figure 7: Photo of RV Polarstern (image credit: AWI)

The Polarstern and MOSAiC:

Even for the reliable Polarstern and her highly experienced crew, the MOSAiC expedition poses quite a challenge. Only thanks to her special technical details, this ship can be the center of an expedition with the dimensions of MOSAiC. Not only is Polarstern capable of operating in the pack-ice zone, but owing to her double-walled steel hull and 20,000 horsepower, she can also easily break through 1.5-meter-thick ice and overcome thicker ice by ramming. Being equipped for sustained operations at temperatures like in the Arctic winter, down to -50º Celsius, Polarstern is also capable of staying the winter in the ice of the polar seas.

However, it’s not nearly so cold inside the ship, where the about 100 MOSAiC researchers, technicians and crew members work and live. In the various scientific labs, the international experts conduct research across the 5 main areas of interest ( atmosphere, ocean, sea ice, ecosystem, biogeochemistry). For MOSAiC, this set-up will be complemented with specific scientific equipment, instruments and lab containers, and even a special additional crane has been installed.

In addition, Polarstern has various vehicles (helicopters, snowmobiles, Pistenbullies, etc.) on board, allowing the researchers to take measurements and gather data not only in the central observatory but also in the distant Distributed Network. The cutting-edge onboard computer system ensures that all scientific data are regularly recorded, saved and forwarded.

Port of Registry


Length, Width, Max. draught (draft)

118 m, 25 m, 11.2 m

Max. displacement, Empty weight,

17,277 tons, 12,012 tons

Commissioning, Engine

1982 (AWI), 4 x KHD RBV 8M540

Enging power, Range

19198 HP (four engines), 19000 nautical miles / 80 days

Max speed, Operation area

16 knots, Everywhere including pack ice zone

Crew, Days on sea per year (2018)

44, 317


Nobiskrug, Rendsburg and Howaldswerke - Deutsche Werft Kiel AG, Germany

Participants per day / long term sailing

none / 53

Table 1: Facts and figures of the RV Polarstern

MOSAiC Expedition status

• 20 March 2020: In the last post, we took a brief tour of some of the sites that make up MOSAiC. In the days since, much has changed with the MOSAiC floe. Specifically, leads have formed in the ice pack that have altered our floe map and impacted our daily schedules drastically. 7)

- Put simply, a lead is just a crack in the ice. It’s never that simple, however. There are many complex processes that determine where and when leads form, how wide they can become, and whether or not they close back up or just re-freeze. Although leads are common features in sea ice and are vitally useful for satellite measurements of sea ice thickness, they still serve as a not-so-gentle reminder that the sea ice can be extremely dynamic, and that we have to be prepared for anything when working out on the ice.

- A few days ago, a small crack formed near the ship that was just a few inches wide when it was first noticed. We were still able to go out on the ice, but it was being monitored closely. About an hour later, everyone out on the ice got a radio call from the ship that it was time to return. The crack had grown to a few meters wide, and ran directly under the ship and out in both directions. It continued to widen for a few hours, but luckily this first crack didn’t form under any installations or sensitive instruments. This lead, however, was just the start.

- In the next hours and next days, many other leads formed off of that initial crack. Some stayed only 1 meter wide, while others grew to 10 meters or more. Almost all work on the ice has been limited, and the leads are monitored closely. The most critical lead formed between the Central Observatory and two important sites: Met City and the Remote Sensing Site. It shifted the sites a few dozen meters from their previous location, to the point where the power cables had to be disconnected before they snapped.


Figure 8: A lead running beneath Polarstern and through the MOSAiC floe, captured from a drone (image credit: Manuel Ernst/UFA)

- While the leads themselves pose threats to the instruments and infrastructure on the ice, they are only half of the concern. When (and if) the leads close again, there is a possibility that ridges could form when the two sheets of ice collide together again. Ridges can grow to several meters tall and would crush anything that was caught in the middle. For now, we are keeping an eye on everything that is on the ice in order to limit any impact that the leads or ridges may have. We also keep our fingers crossed that the ice stabilizes soon!


Figure 9: A large (about 3 m tall) ridge that formed in the vicinity of Polarstern. The unconsolidated nature of the ice blocks shows that this ridge formed relatively recently (image credit: Steven Fons)

• 16 March 2020: On Thursday 12 March, the Norwegian government announced comprehensive measures to combat the spread of the corona virus, effective immediately. As a result, all travellers to Norway from non-Nordic countries who do not have a residence permit will most likely have to immediately leave the country again or be placed in quarantine for 14 days. In response, and due to the highly dynamic development of the corona pandemic, on Friday 13 March the MOSAiC project management decided to temporarily suspend the aerial survey campaigns planned for this spring and based in the Svalbard archipelago, which is under Norwegian administration. There are currently three icebreakers underway in the Central Arctic for the MOSAiC expedition. 8)

- The survey flights, focusing on the atmosphere and sea ice, were to be carried out in four sub-campaigns from March to September. The two research planes Polar 5 and Polar 6 were originally scheduled to reach Svalbard on 11 March. After a participating researcher tested positive for corona last week, the start of the campaign had to be pushed back. In light of the current situation, the sub-campaigns planned for spring will no longer be possible.

- “The highly unusual situation at the moment leaves us no choice. We’d like to thank everyone who was involved in the months of preparation, and who did everything within their power, up to the last minute, to make the flight campaigns a reality,” says Dr Andreas Herber from the Alfred Wegener Institute, Helmholtz Center for Polar and Marine Research (AWI), and coordinator of the MOSAiC airborne campaigns. According to Herber, the AWI will closely monitor the situation over the next several weeks and explore alternative solutions, e.g. extending the two sub-campaigns scheduled for the summer.

- In the meantime, on board the icebreaker Polarstern, the MOSAiC expedition continues. The ship’s current coordinates are 87°7’ North and 16°59’ East. Those researchers and crew returning from the second leg of the expedition on board the Russian icebreaker Kapitan Dranitsyn have made good progress through the ice since departing from the MOSAiC floe on 6 March. On 14 March they rendezvoused as planned with another Russian icebreaker, Admiral Makarov, at 84°48’ North and 42°35’ East, to bunker additional fuel for the voyage home.

- Moreover, the planned crew exchange by airplane in early April should – barring unforeseen developments – still be possible. Nevertheless, both the project management and participants are preparing for the additional challenges the pandemic may entail. For example, Norway’s quarantine policy will most likely remain in effect in April, which means participating researchers will need to allow a great deal of time prior to the fourth leg of the expedition. All participants have been requested to use the utmost caution to avoid infection. Before being allowed on board the ship, they will be tested for corona twice: once before leaving their point of origin, to avoid spreading the virus by travel, and once more at the expedition’s point of departure, to minimize the risk of introducing the virus among the expedition team. Further, Polarstern is equipped with a quarantine ward, in the event that, despite all precautions, there is an infection on board.


Figure 10: The MOSAiC aerial survey campaigns with Polar5 and Polar6 are temporarily suspended (photo credit: Alfred-Wegener-Institute)

- “We’ve rapidly responded to the pandemic with a comprehensive safety concept and strict medical-diagnostic profile, in order to reduce the risks for all expedition participants to a minimum. The spreading wave of infections poses an immense challenge for this international expedition. Our safety concept represents a commensurate response to the current situation. That being said, no one can predict how that situation will change over the next few months; therefore, we will continually reassess and update the concept as needed. For the time being, we have to ‘navigate by sight’ and focus on finding the safest and most sensible course for the logistical operations at hand,” says MOSAiC Expedition Leader Prof Markus Rex from the AWI. In this regard, the expedition closely collaborates with the health authorities of the countries involved, he adds, focusing on the health and safety of all expedition participants as the highest priority.


Figure 11: MOSAiC participants watch the arrival of the Admiral Makarov on the bridge of Kapitan Dranitsyn (photo credit: Benjamin Rabe)

• 16 March 2020: Central to the entire MOSAiC Expedition is the MOSAiC Floe: a large sheet of sea ice that was carefully selected back in October as the ideal place to anchor Polarstern for an entire year. It was chosen due to its size, structure (a mix of thick multiyear sea ice and thinner first year sea ice), and forecasted drift trajectory. Over the past five months, it has become a second home for many scientists. Here’s a brief tour of our workplace: 9)

The Central Observatory (CO):

- Nearest to Polarstern, the CO, is the primary place where measurements are taken, both from continuously operating instruments and from sampling trips off of Polarstern. It houses many installations, from small stakes just a few inches tall, to larger huts and tents that can comfortably fit a few people inside, to 25-meter-tall towers with dozens of instruments installed. Most installations are grouped into ‘cities’ by scientific discipline. There is MET (meteorology) City, Ocean City, Balloon Town (for weather balloons – not clowns), the Remote Sensing Site, and the ROV (Remote Operated Vehicle) Site, to name a few. There are also clean areas dedicated to the sampling of snow, measuring ice strength, and studying biogeochemical processes.

- Throughout the CO, there are carefully placed roads that lead from Polarstern through the Logistics area (where snowmobiles and other gear are parked) and to the different cities. Perhaps most importantly, there is also a ‘trip wire’ alarm around the CO that is able to send up a signal flare if a polar bear walks into it, providing an additional safety measure when out on the ice.


Figure 12: A map of the MOSAiC Floe, focused on the Central Observatory (image credit: AWI)

Area II:

- Outside of the CO is known as Area II. This mainly houses the “Dark Site” – a place where sea ice cores are taken each week. The Dark Site consists of two different locations from which cores are drilled: a first year ice site and a second year ice site. This area is located far from the lights of Polarstern and kept as dark as possible, so as not to disturb some of the ecological work that is going on. During the winter darkness, anyone visiting the Dark Site had to use a red headlamp, which has been proven to have the least impact on the organisms living below the ice. Due to the distance away from the CO and Polarstern, visiting Area II requires additional preparation and safety gear. My main task on MOSAiC is drilling sea ice cores, so I will venture to Area II at least once per week during leg 3.

The Distributed Network (DN):

- Furthest from Polarstern is the Distributed Network, which is home to exclusively autonomous instrumentation. The DN sites are not part of the MOSAiC Floe, but instead range from around 5 kilometers to over 30 kilometers away from Polarstern. Almost all sites require a helicopter to visit, usually these visits consist of fixing broken instruments or changing batteries. The purpose of the DN is to have measurements far from Polarstern, in order to determine the representativeness of the MOSAiC floe with respect to the ice in the rest of the Central Arctic.

- Together, these areas make up the field sites of MOSAiC. It’s a pretty cool place to work!

• 13 March 2020: The MOSAiC Leg 3 team is officially on board Polarstern, and science activities have quickly begun. 10)

- The first few days on board were filled with handover activities from the previous leg of the expedition. Leg 3 scientists met with members from leg 2 to get a general introduction to the instruments, experiments, and life on the MOSAiC ice floe. Given that leg 2 was on Polarstern since late December, they truly are experts in the scientific activities occurring out on the ice.

- During the handover, I met with members of the leg 2 ice team and visited different sites around the floe where most of my work will take place. Since it is my first time on Polarstern, I was also shown where different labs and workspaces are located, where to find tools and instruments to take out into the field, and, perhaps most importantly, where the coffee machine is! These days were invaluable for preparing the leg 3 members for work, and even more important to ensure that MOSAiC continues to run smoothly with a new team at the helm.

- After the handover, it was time to say farewell to leg 2. We sent them off in true ‘Arctic expedition’ style with a gathering out on the sea ice between the two ships. All members from the science teams as well as the crews from both the Polarstern and the Kapitan Dranitsyn were invited for bonfires, hot tea, and group photos. The next morning, Kapitan Dranitsyn left on its return voyage to Tromsø, and leg 3 was left alone on Polarstern.

- It didn’t take long for us to get started. The morning of the Dranitsyn departure, some teams already set out onto the ice to take measurements. I was working with another member of the ice team to construct a radiation station that we deployed on the ice a few days later. This type of station holds a few instruments that detect the amount of solar radiation both above and below the sea ice. It was necessary to deploy these instruments early in the leg, so that they would be operational for the first sunrise of the year. So far, we have been in a state of constant twilight – a red-orange sky for most of the day. In a few days, the sun will rise above the horizon for the first time in 2020. With this new station (Figure 14), we will now be able to measure the amount of solar energy that reaches (and penetrates through) the sea ice.

- It has been extremely busy since leg 2 departed, but everyone is excited to be working on the ice. Here’s to a successful leg 3!


Figure 13: Scientists from MOSAiC Leg 3 walk from the Kapitan Dranitsyn to their new home on Polarstern (photo credit: NASA, Steven Fons)


Figure 14: Alexey (left) and Steven (right) deploying the radiation station (photo credit: Philipp Anhaus/AWI)

• 02 March 2020: For days, fast sea ice had slowed the progress of the resupply icebreaker Kapitan Dranitsyn; bound for the North Pole, her mission was to support the second exchange of researchers and crew in the MOSAiC expedition. Nevertheless, she steadily drew closer to her destination, and finally, at 12:20 pm (CET) on Friday, 28 February, dropped anchor 970 meters from Polarstern, moored to the same floe. While the handover is in full swing on the MOSAiC floe, in Russia another icebreaker will soon leave port in order to supply Kapitan Dranitsyn with additional fuel on her return trip. 11)

- This past week there were not one, but two new records in the history of polar research, as the University of Cambridge’s Scott Polar Research Institute has reported: on 24 February Polarstern’s drift took her to 88°36’ North, just 156 kilometers from the North Pole. Never before had a ship ventured so far north during the Arctic winter. And two days later, the Russian icebreaker Kapitan Dranitsyn, shortly before her rendezvous with Polarstern at 88°28’ North, reached the northernmost position on her mission, marking the first time a ship had made it so far north under her own power, so early in the year.

- “These records represent milestones in the MOSAiC expedition. They demonstrate the success of the logistical concept, and provide the basis for the unprecedented scientific data that is being gathered during the expedition,” says Prof Markus Rex from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) in Potsdam, Leader of the MOSAiC expedition. “My hat goes off to Captain Alexandr Erpulev for successfully navigating the icebreaker Kapitan Dranitsyn through the Arctic winter and virtually to the North Pole,” adds Polarstern Captain Stefan Schwarze, underscoring this nautical achievement. “Given the current sea-ice situation, the delay is absolutely in keeping with what had to be expected,” Rex emphasizes. Following the first few months of the expedition, Rex returned from the Arctic on board Kapitan Dranitsyn and will return to Polarstern in April.

- Together with the Logistics Division of the Alfred Wegener Institute, he’s spent the past several days working out how to provide the resupply icebreaker with additional fuel. Since the fast sea ice forced Kapitan Dranitsyn to consume more fuel than originally planned, the icebreaker Admiral Makarov is expected to depart from Murmansk on 3 March and follow an intercept course with Kapitan Dranitsyn, so as to refuel the latter in the Arctic sea ice.

- The exchange of staff and equipment is taking place on foot, with snowmobiles and with snowcats hauling heavily laden sledges. On board Polarstern and in the Ice Camp, the new expedition members are being instructed on various tasks by their predecessors. Extreme caution is the prime rule, especially when working on the ice, where the wind-chill temperature can now reach 58 degrees below zero Celsius. Thanks to these extreme temperatures, only a day after her arrival, the channel of open water left behind by Kapitan Dranitsyn had refrozen so rapidly and intensively that the researchers could walk on it. The temperatures also pose a problem when it comes to transferring provisions; for example, fresh produce has to be transported in heated containers. It’s still too soon to say how long the transfer of crew and equipment will take to complete, partly because the two ships’ cranes only work very slowly in the frigid conditions.


Figure 15: The icebreakers Kapitan Dranitysn and Polarstern in the Arctic ice (photo: AWI, Ernst Stürmer)

- Shortly before beginning the journey home, Prof Christian Haas from the Alfred Wegener Institute, Chief Scientist for the second leg, took stock of the situation. According to the sea-ice expert, “Over the past few months, we’ve been able to observe winter at the North Pole more consistently and precisely than ever before. The ice thickness has doubled to an average of 160 cm since December, which corresponds to a growth rate of roughly ten centimeters per week.”

- In addition, with the aid of helicopter laser-scanner readings, Polarstern’s radar system, and buoys, the researchers were able to observe how the ice deformed, and channels opened and closed again. Thanks to the warming of the Arctic Ocean, smaller and thinner ice floes are becoming more common. Driven by the wind, they can collide and overlap, producing pack ice hummocks up to four meters tall. Since a great deal of their mass lies underwater, some hummocks are 20 to 30 meters thick – a phenomenon that now represents a challenge for the resupply icebreakers.

- In contrast, readings taken on the ice, on board ship, and with weather balloons revealed that the air temperature just above the ice was far lower than at a height of 20 meters. In the lowermost ten meters there can be temperature differences of more than 4 degrees Celsius, which has a major influence e.g. on the increase in ice thickness. Lastly, ROV dives showed how life under the ice goes on, even in the long Polar Night. “We’ve never had the opportunity to study the zooplankton and polar cod up here so extensively at this time of year. In February we even repeatedly saw a seal under the ice, which is apparently finding sufficient food, despite being practically at the North Pole. And on the surface, we sighted a polar bear and several Arctic foxes,” says Christian Haas, summarizing recent observations.

- Sometime in the next few days Prof Torsten Kanzow from the Alfred Wegener Institute, who arrived on Polarstern by helicopter last Wednesday, will take over as Chief Scientist for the third leg of the journey. This phase of the expedition will in part be characterized by the return of daylight. Even now, there is a perceptible several-hour-long phase of twilight each day, which also makes the cargo transfer a bit easier to manage. Over the next few weeks the sea ice will become even denser, which is why the next exchange, in April, will most likely be done by plane. For this purpose, the snowcats were used to prepare a 900 m long airstrip on the ice. In addition to the flights for exchanging staff and crewmembers, the third leg will also include scientific missions with the research airplanes Polar 5 and Polar 6, which will then be based in Svalbard and are slated to make flights to the still drifting Polarstern.

The expedition in numbers

- From 13 December 2019 to 27 February 2020, the Transpolar Drift carried Polarstern a total distance of 672 km; however, given the meandering course of the drift, the ship only covered a linear distance of 406 km.

- In the same period, the top drift speed, 1.7 km/hour, was reached on 1 February 2020.

- The expedition came within 156 km of the North Pole.

- Using snowcats, engineers created a 900 m long airstrip on the ice.

- On 1 February the air temperature plummeted from an unseasonably warm minus 11.4 degrees to minus 38.2 degrees Celsius, the most intense cold snap observed during this leg of the expedition.

- During the second leg of the journey, the expedition members and crew consumed 8,100 eggs, 1,360 kg of potatoes, and 86 jars of Nutella. Needless to say, that’s not all they ate.

- The longest excursion was a ski tour to an automated monitoring station roughly 10 km from Polarstern. The entire tour was completed in total darkness.

- Only 1 polar bear was sighted during this leg – at night, by an automated camera that just happened to snap a photo while the bear was sniffing the instruments at the remote sensing station.

- Due to fog and a major snowstorm, there were 3 days on which work out on the ice had to be suspended.

- The experts gathered 34.3 terabytes of data.

• 24 February 2020: Four months into the MOSAiC drift campaign, the North Pole is less than 160 km away. Current predictions by international forecast centers and researchers, collected and evaluated by the Sea Ice Drift Forecast Experiment (SIDFEx), suggest that there is a chance that the drift will take the expedition even further North. However, the tight grip of the westward Transpolar Driftstream makes it unlikely that the ship will pass the North Pole in the direction of North America. There is other good news: The probability to get pushed into the open ocean before October 2020 is still not more than 10-15%. 12)

- On Sunday, February 23rd 2020, the MOSAiC expedition onboard the icebreaker RV Polarstern reached 88.5987°N, besting the northernmost point of Fridjof Nansen’s expedition 125 years ago by more than two degrees. While Nansen’s goal was to reach the North Pole, MOSAiCs science plan has no specific interest in this target. Nevertheless, being so close, the question how close to the pole MOSAiC will get is on the mind of participants and observers. Is the camp destined for a continuation of its straight course toward the Fram Strait, named after Nansen’s ship, or could the expedition still pass the pole on the “other side”, across the date line?

Drift forecasts are essential for the planning of expeditions

- When planning the route for his 1893 expedition to reach the North Pole, Nansen had little to go by other than a few pieces of debris from the shipwrecked Jaennette that had been found off the south-west coast of Greenland. After more than a century of research and innovation, planning and execution of science missions such as MOSAiC can now draw on millions of Earth observations and complex weather and climate models running on supercomputers that simulate the evolution of our environment based on the laws of physics. The planning for the MOSAiC drift, in particular where and when to start, relied on satellite observations of Arctic sea ice drift from the previous two decades. This historical information provided a sense of what one might expect for 2019/20. Many months before a planned mission, such climatological information so far remains the best planning tool. This is because modern forecast systems that simulate the ice motion have difficulty adding much skill beyond several weeks forecast lead time. The chaotic nature of the atmosphere makes the winds that drive the ice motion largely unpredictable beyond some point.

- However, when it comes to the drift over the next days to weeks, real-time information from modern forecast systems can sharpen the prediction significantly. These forecasts are useful for mission planning and for applications such as the ordering of high-resolution satellite images of targets moving with the ice. Assessing how well these systems work, how to improve them, and how to best integrate them with historical information to generate seamless forecasts from days to months, is the main motivation for the Sea Ice Drift Forecast Experiment (SIDFEx), an initiative of the Year of Polar Prediction (YOPP). Instead of providing forecasts based on a single system, SIDFEx is bringing together forecasts from more than a dozen systems from many countries, to increase accuracy and to characterize forecast uncertainty.

Sea Ice TickerNr. 23 of 28 February 2020 13)

- Many people following the drift of the MOSAiC expedition are on the edge of their seats; they can’t wait to see just how far north the drift will continue! Careful planning prior to the expedition helped predict how the drift would progress, and which course the MOSAiC camp would follow. This was only possible thanks to numerous drift-route calculations, based on satellite observations, meteorological and climate data from the past 20 years. Yet even with the advanced climate models and supercomputers available today, there’s no 100% guarantee. MOSAiC’s projected drift corridor included potential routes that could take the camp either to the west or east of the North Pole, or ideally right across it.

- During their drift 125 years ago, Fridtjof Nansen and his crew crossed the northernmost parallel at 85° 57’ North on 17th November 1895, roughly 450 km from the North Pole. On 24 February 2020, RV Polarstern reached her northernmost point to date (88° 35’ North), putting her only ca. 150 km from the Pole and significantly closer to Nansen’s goal. However, the latest forecasts indicate that the westward drift will now increasingly be influenced by a southward component, as a result of which the Transpolar Drift will slowly begin taking the MOSAiC camp further from the North Pole and toward Fram Strait. Drifting across the North Pole was never the expedition’s declared goal; rather, it was to improve our understanding of the Arctic climate system and arrive at more accurate reflections of it in global climate models.


Figure 16: MOSAiC is just a a stone’s throw away from the North Pole (image credit: MOSAiC Expedition)

• 16 December 2019: Spare a thought this Christmas for researchers hunkered down on their Polarstern icebreaker, adrift in the frozen Arctic Ocean. Subjected to temperatures as low as –45°C and the perpetual darkness of the polar winter, they are willing participants in MOSAiC – the world’s largest and longest polar research expedition. Despite the darkness, however, the researchers and crew remain aware of what is happening close by. How? With the help of radar imaging satellites. 14)

- After entering the Arctic Ocean in October, the Polarstern has been drifting across the central Arctic at about 7 km per day with the wind and currents expected to carry it close to the geographic North Pole before exiting next spring or summer.


Figure 17: Polarstern shrouded in darkness. The MOSAiC expedition of AWI will make a major contribution to Arctic climate science. During the polar winter, researchers are subjected to temperatures as low as –45°C and the perpetual darkness (image credit: Alfred-Wegener-Institute/Esther Horvath , CC BY-SA 3.0 IGO)

- On board, the scientists are carrying out multiple experiments on the sea ice around the ship to better understand the impact of climate change on sea ice and the Arctic environment. The team has now established hundreds of instruments on the sea ice surrounding the ship within a distance of 50 km.

Figure 18: This animation shows Polarstern’s route and drift as well as the growth of the winter sea ice (image credit: MOSAiC team/US National Snow & Ice Data Center for sea-ice extent) 15)

- Despite the darkness currently enveloping the ship as it drifts through the frozen sea, the researchers and crew are not blind and remain aware of what is happening thanks to radar imaging satellites of Europe’s Copernicus program, Canada, Germany and Japan.

- The crew and scientists monitor the sea ice and generate remarkable maps of the sea-ice floes surrounding the ship. These radar satellites cross the Arctic on a daily basis and carry with them their own source of illumination, which allows them to pierce through the Arctic winter darkness, continuously sensing and mapping the sea-ice conditions below.

- Suman Singha, from the German Aerospace Center’s Remote Sensing Technology Institute, helps coordinate the acquisition of images from different satellites and is responsible for relaying the precious information further to the ship.

- “This information is very much needed at Polarstern, especially at the beginning of the expedition, when the challenge was to find the right kind of ice floe able to harbor both the Polarstern and the deployment of all the scientific instruments on the ice around the ice breaker,” says Dr Singha.

- “Here we made use of high-resolution radar images from the German TerraSAR-X satellite to help locate the best-possible floe, which has since been given the name Fortress. Monitoring the safety of the floe thus remains a constant challenge.”


Figure 19: Radar image from Japan’s ALOS-2 satellite of the sea ice near the Polarstern icebreaker. Polarstern is drifting in the Arctic sea ice for a year for the MOSAiC polar research expedition. During the polar winter, the researchers use radar satellite images such as this to monitor the sea ice in the surrounding area. In this false-color image, which was acquired on 19 November 2019, dark blue cracks show open water leads or thin ice between the ice floes. The white filament-like structures are typically sea-ice ridges or other deformed sea ice (image credit: JAXA)

- Also contributing to the international mapping effort are Europe’s Copernicus Sentinel-1 satellites which provide continual wide-area coverage of the site, helping to follow and predict the ever-changing drift of the sea ice up to 300 km away from the ship.

Figure 20: This video is based on data acquisitions from the Copernicus Sentinel-1 mission between 3 October and 31 October 2019. It remains constantly centered on the Polarstern (bright dot starting at the center of the grid). Polarstern is a German research icebreaker spending a year trapped and drifting in the Arctic sea ice so that scientists from around the world can study the Arctic as the epicenter of global warming and gain fundamental insights that are key to better understand global climate change. The video shows how the initial grid distorts over time by the uneven ice drift over time within the grid array. This results in opening (ice divergence) and closing (ice compression and ridging), shear and vorticity. This shear caused a massive crack to form through the experiment ice floe, disrupting the experiments and forcing movement of some of the instrumentation [video credit: ESA, the image contains modified Copernicus Sentinel data (2019), processed by R. Kwok (JPL)]

- The Japanese ALOS-2 satellite with its PalSAR-2 sensor uses a much longer wavelength than both Copernicus Sentinel-1 and TerraSAR-X to map sea-ice floes and conditions below.

- ESA’s Malcolm Davidson said, “Wavelength matters when it comes to radar satellites as a particular wavelength greatly influences the information provided by the satellite.

- “In Europe we are very interested in the additional information that ALOS-2 can provide on sea-ice conditions especially now that we are developing our own long-wavelength radar satellite called the L-band Synthetic Aperture mission, ROSE-L – which is one of the six Copernicus high-priority candidate missions.

- For instance, detecting sea-ice ridges is critical for safe navigation in the Arctic and these are much easier to identify with ALOS-2 than with the existing European satellites.”

- While Polarstern now drifts through the frozen and dark ocean for the coming months, the radar eyes in the sky will continue to monitor its progress through the Arctic and accompany the researchers through the rest of this remarkable expedition.


Figure 21: The researchers participating in the MOSAiC expedition not only have to keep an eye on the ever-changing sea ice, but also on visitors. These polar bears seem to be enjoying playing with the marker flags. Spearheaded by AWI, MOSAiC is the biggest shipborne polar expedition of all time. It involves the Polarstern German research icebreaker spending a year trapped and drifting in the sea ice so that scientists from around the world can study the Arctic as the epicenter of global warming and gain fundamental insights that are key to better understand global climate change (image credit: AWI, Esther Horvath, CC BY-SA 3.0 IGO)

• 18 November 2019: The MOSAiC mission involves 600 people from 19 countries. From a ship trapped in the sea ice, scientists are taking a diverse range of measurements that could help to transform climate models. Carbon Brief’s science writer Daisy Dunne joined the expedition for its first six weeks in the autumn of 2019. This is the first of four articles focused on MOSAiC research. 16)

- Landing a 12-ton helicopter on floating sea ice in the Arctic Ocean is no easy task. But the Russian research crew on this 14-seater Mi-8 have a surprisingly simple trick to make the job easier. As the helicopter approaches the ice, a crew member throws open the door and kicks out an old car tire.

- The crew watch as the tire falls to the ice below. The black of the tire stands in contrast to the grey and bluish tones of the sea ice and the sky above, giving depth to the seemingly flat landscape. This reference point helps the pilots to work out how far they are from the ice surface.

- As the helicopter approaches the ice and hovers just above its surface, Dr Tomasz Petrovsky, a sea-ice specialist from the Arctic and Antarctic Research Institute (AARI) in St Petersburg, jumps out onto the ice and uses a hand drill to burrow through to the ocean below.

- The rest of the research team look on intently. The amount of time it takes to drill through the ice is a good indicator of how thick it is. Petrovsky gives a thumbs up, signalling that the ice is thick enough for the research team to safely get out on the ice and start collecting data.

- In the -6ºC chill, a team of six researchers pile out onto the ice and begin to take more thickness measurements as the helicopter waits nearby. No human has set foot on this chunk of ice before, meaning each step forward poses a potential risk. The ice surface is covered by several centimeters of snow, which could be concealing cracks or stretches of thin ice.

- To navigate the ice safely, the research team keep a close eye on their surroundings. The presence of jagged, tall structures sticking up from the ice surface help the researchers to identify areas of thick ice known as “pressure ridges”. The color of the ice, too, can give an indication of its thickness. Thin ice tends to appear darker in color because it is more translucent and, therefore, shows more of the murky ocean below.

- “Did you see the bear tracks?” Jakob Belter, a sea ice PhD student at the Alfred Wegener Institute (AWI) in Germany, shouts above the whirring of the helicopter blades. Only a couple of meters away, a set of large round paw prints have been left in the snow. Polar bears are widely considered to be one of the largest threats to the safety of scientists on the sea ice. Up ahead, an armed polar bear guard keeps watch of the horizon.


Figure 22: Jan Rohde and Jakob Belter take ice thickness measurements in front of an Mi-8 helicopter in the Central Arctic Ocean (image credit: Daisy Dunne for Carbon Brief)

- The researchers are trying to find chunks of sea ice, known as ice floes, that could be large and thick enough to support a vast array of scientific equipment for an entire year. The chosen ice floes will act as the scaffolding for a network of floating research stations. These stations will play a key role in MOSAiC, one of the largest and most complex Arctic research expeditions ever attempted.

• 16 October 2019: One central task during the first phase of MOSAiC has been completed. Supported by the highly experienced crew and the not less experienced pilots of the MI-8 helicopters, an international team of scientists onboard Akademik Fedorov successfully deployed the so-called Distributed Network. This is the complex system of buoys and measurement instruments that is now drifting in the environs of the central observatory Polarstern in a distance of up to 50 kilometers. 17)

- The larger and smaller sites were partially deployed from aboard the ship, with scientists using the gangway to get access to the ice. In part, they were also deployed on smaller ice floes using helicopters. However, the deployment of the complicated instruments of the Distributed Network on thin and fragile ice presented quite a challenge – a challenge the scientists were also able to take on owing to the wealth of experience and knowledge of the Russian team of AARI sea ice experts.


Figure 23: The international team of scientists onboard Akademik Fedorov successfully deployed the so-called Distributed Network (photo credit: AWI, Mario Hoppmann)

• 04 October 2019: MOSAiC expedition begins its ice drift on a floe at 85 degrees north and 137 degrees east. — After only a few days of searching, experts from the MOSAiC expedition have now found a suitable ice floe, where they will set up the research camp for their one-year-long drift through the Arctic Ocean. Consequently, one of the most important milestones in the expedition has been reached ahead of schedule, and before the Polar Night falls. Nevertheless, the search, which involved satellite imagery, two icebreakers, helicopter flights and scouting missions on the surface of the ice, was an enormous challenge – partly because, after the warm summer, there were very few sufficiently thick floes in the expedition’s start region. 18)

- The die is cast: The MOSAiC team has now selected the floe that will serve as the base of operations for their one-year-long ice drift around the North Pole with the German research icebreaker Polarstern. This was preceded by an intensive search combining satellite imagery and helicopter flights over the target area in the Central Arctic, which were supported by the icebreaker Akademik Fedorov, operated by Russia’s Arctic and Antarctic Research Institute (AARI). The participating researchers closely examined 16 floes that, on the basis of satellite imagery, were potentially large enough to accommodate the ice camp. They subsequently met on board Polarstern to compare their findings, ultimately agreeing that the ice drift should be prepared for on a floe measuring roughly 2.5 by 3.5 km, and located at 85 degrees north and 137 degrees east. The floe, which Polarstern will allow herself to become frozen to, is currently drifting in alternating directions, at up to 10 km/day.

- “After a brief but intensive search, we’ve found our home for the months to come. The ice floe is characterized by an unusually stable area, which we are confident can serve as a good basis and point of departure for establishing a complex research camp. Other parts of the floe are typical of the new Arctic, which is home to thinner, less stable ice. And precisely this combination makes it very well suited to our scientific projects. After carefully reviewing all relevant data, including that from our Russian partners, we came to the conclusion: it may not be the perfect floe, but it’s the best one in this part of the Arctic, and offers better working conditions than we could have expected after a warm Arctic summer,” explains MOSAiC expedition leader Markus Rex of AWI. “We’ll have to wait and see if it’s also stable enough to withstand the autumnal storms that are now brewing. But we’re prepared for all scenarios,” he adds.


Figure 24: Polarstern arrives at a potent ice floe. After comprehensive measurements, the involved scientists decided it to be the MOSAiC ice floe, with the location 85ºN 137ºE on 30 September 2019 (photo credit: AWI, Esther Horvath)

- On 28 September the first researchers from Polarstern set foot on the floe, which had long been a preferred candidate thanks to the promising analyses of the satellite data. On the radar images produced by the satellites, the dark, nearly oval floe stood out thanks to a large, bright region in its northern section. This clearly set it apart from all of the other potential floes, which were consistently dark in the radar images. In the meantime, the experts have dubbed this region ‘the fortress’: made up of highly compressed, several-meter-thick ice, it offers higher stability and a solid basis for the ice camp, which will be erected far above it. In contrast, the darker regions, which are riddled with frozen-over meltwater pools and thin, porous and less stable ice, are typical representatives of the ice conditions in the new Arctic. Here the ice thickness is ca. 30 cm near the freshly frozen-over pools, and between 60 and 150 cm in the older ice between them, although here, too, the bottommost 30 to 40 cm of the ice are extremely porous and less stable.


Figure 25: Polarstern (left) and Akademik Fedorov (right) dock next to each other(photo credit: AWI, Esther Horvath)

- The researchers were unable to determine the floe’s makeup using satellite imagery alone; it took several days and nights of intensive work on the floe itself to gather the requisite data for making a sound choice. In this context, they used an electromagnetic sensor, which they hauled over the ice on foot or with a Skidoo, to map the ice thickness. Ice core samples also yielded data to help assess the ice’s structure. Working in the dark, and in unfamiliar territory, posed a serious challenge. These efforts were coordinated and monitored with infrared cameras from Polarstern’s bridge. Further, members of the expedition’s polar bear patrol accompanied the researchers on the ice to ensure their safety.

- In a final step, a helicopter-mounted laser scanner was used to create a three-dimensional model of the floe’s surface. This map, created during the scouting phase, will help the experts plan the next step: setting up the ice camp. Time won’t be on their side: starting today, the sun will no longer rise over the horizon, and there will only be a few more days with partial light at noon.

- The MOSAiC expedition, spearheaded by AWI, entails a number of unprecedented challenges. The project has an overall budget of ~ 140 million euros. In the course of the one-year-long drift, ~300 experts hailing from 17 countries will be on board. Their common goal: to investigate for the first time the entire climate system in the Central Arctic. To do so, they will gather data on five major aspects – Atmosphere, Sea Ice, Ocean, Ecosystem and Biogeochemistry – in an effort to better understand the interactions that shape the Arctic climate and life in the Arctic Ocean.


Figure 26: First group of scientists lands on an ice floe. Gunnar Spreen (left) and Matthew Shupe (right) examine a potential ice floe for MOSAiC on 30 September 2019, (photo credit: AWI, Esther Horvath)

•21 September 2019: The most ambitious research expedition ever to target the central Arctic got underway as the German icebreaker RV Polarstern pulled out of Tromsø on 20 September 2019, destined for an ice floe where it will serve as a drifting base for hundreds of scientists during the next 13 months. 19)

- More than 10 years after NOAA/CIRES scientist Matthew Shupe of the NOAA ESRL/PSD (Earth System Research Laboratory/Physical Science Division) conceived of the idea, the Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) has become a $150 million voyage of discovery led by the Alfred Wegener Institute, with significant funding by the US. Department of Energy and other US agencies. More than 400 scientists from 19 countries, including some of the world’s top Arctic researchers, will participate.

- The expedition is led by Germany’s Alfred Wegener Institute (AWI), with key support from the U.S.’s CIRES (Cooperative Institute for Research in Environmental Sciences) at the University of Colorado Boulder and NOAA ERSL/PSD (Earth System Research Laboratory/ Physical Science Division). Overall, 17 nations are involved; the U.S. represents the second largest national contribution with funding support from NOAA, NSF, DOE, and NASA. 20)

- PSD and CIRES scientists have been heavily involved in MOSAiC since the beginning, including developing the initial concept for a year-long, multi-disciplinary project in the Arctic sea ice; playing the chief editorial role for the MOSAiC Science Plan; serving in many leadership roles; implementing multiple science projects; and engaging in outreach and communications activities.

Years of planning help ease a hectic departure

- This is the first time a modern research icebreaker will operate in the direct vicinity of the North Pole year-round, including the nearly six-month long polar night during winter. In terms of the logistical challenges involved, the total number of participants, the number of participating countries, and the available budget, MOSAiC represents the largest Arctic expedition in history. “It’s really amazing to see all the composure here during a really stressful time,” said Shupe, the U.S co-lead on the massive expedition, as dozens of scientists worked to install equipment on board just hours before Polarstern’s departure. “I am really energized by all these people and energy moving in the same direction. I see this around every corner of the ship.”

- Researchers will be conducting experiments and collecting data from the atmosphere, ice and ocean with instruments on board the Polarstern, and from locations up to several miles away, to explore the physical, chemical, and biological processes that drive the Arctic atmosphere, sea ice, ocean, and ecosystem. Results from the mission will help scientists improve models and forecasts of local, regional, and global weather and climate.


Figure 27: Some of the PSD team in Tromsø, Norway, (L-R) Chris Cox, Matt Shupe, Byron Blomquist, Sara Morris (Photo credit: Sara Morris, CIRES)

First challenge: Where do you park an icebreaker?

- After departing Tromsø, 350 miles north of the Arctic Circle, the ship will position itself so that it freezes into drifting ice as the polar night descends. Research during the roughly six months of darkness will present challenges on top of those delivered by the frigid Arctic winter. Special lights, night-vision goggles to watch for polar bears, and activities designed to maintain a healthy daily schedule in the close confines of the ship are some of the adaptations scientists will have to make.


Figure 28: The German icebreaker Polarstern will serve as the hub of a floating base camp for hundreds of scientists studying the Arctic during the year-long expedition. To learn more about the logistics of the mission, visit: (image credit: AWI). The expedition will be resupplied by four icebreakers from Sweden, Russia and China.

- As soon as the Polarstern has dropped anchor at an ice floe, a small city appears on the surface of the ice. Though the MOSAiC researchers don’t live there, it is where they conduct much of their research.

- And they do so using a carefully planned structure: just as blacksmiths, potters and other artisans each had their own district back in the Middle Ages, in the ‘Ice Camp’ meteorologists and climate researchers, marine biologists and specialists for snow, sea ice and other disciplines work together in smaller camps of their own, which are also home to the specific equipment they need.

What happens in the Arctic doesn’t stay in the Arctic

- For the Alfred Wegener Institute’s Markus Rex, leader of the MOSAiC expedition, the Arctic is the “kitchen” for weather in the northern hemisphere. Extreme weather conditions like outbreaks of cold Arctic air in winter, or heat waves in summer, are linked to the changes in the Arctic, he said. Given that Arctic change is likely to have a global impact, research to improve climate models is of utmost importance.

- “There aren’t any reliable prognoses of how the Arctic climate will develop further or what that will mean for our weather,” said Rex. “Our mission is to change that.”

• 20 September 2019: After a decade of preparations, it’s finally time: this evening at 8:30 p.m. the German icebreaker Polarstern will depart from the Norwegian port of Tromsø. Escorted by the Russian icebreaker Akademik Fedorov, she will set sail for the Central Arctic. On board researchers will investigate a region that is virtually inaccessible in winter, and which is crucial for the global climate. They will gather urgently needed data on the interactions between the atmosphere, ocean and sea ice, as well as on the ecosystem. Thanks to the collaboration between international experts, the one-year-long ice drift past the North Pole will take climate research to a completely new level. 21)

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19) ”A Year Locked in Ice: Unprecedented international expedition to explore the central Arctic gets underway,” 21 September 2019, ERSL/PSD, URL:


21) ”This Evening Sees the Start of MOSAiC – the Greatest Arctic Research Expedition of All Time,” AWI Press Release, 20 September 2019, URL:

The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (

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