15. September 2020
Studying ice at the centimetre scale

DLR cam­era ex­am­ines Arc­tic sea ice from the air as part of the MO­SA­iC ex­pe­di­tion

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Aeronautics
Ice structures and polar bear tracks on an Arctic ice floe
Ice struc­tures and po­lar bear tracks on an Arc­tic ice floe
Image 1/6, Credit: DLR (CC-BY 3.0)

Ice structures and polar bear tracks on an Arctic ice floe

With a res­o­lu­tion of two cen­time­tres per pix­el, this aeri­al im­age ac­quired by the MACS po­lar cam­era from a flight al­ti­tude of 100 me­tres in the Fram Strait be­tween Green­land and Spits­ber­gen clear­ly shows the tracks of po­lar bears. The rough­ness and struc­ture of the ice can al­so be seen, which are par­tic­u­lar­ly in­ter­est­ing for analysing sea ice. 
Research aircraft Polar 6 at Longyearbyen Airport, Spitsbergen
Re­search air­craft Po­lar 6 at Longyear­byen Air­port, Spits­ber­gen
Image 2/6, Credit: DLR (CC-BY 3.0)

Research aircraft Polar 6 at Longyearbyen Airport, Spitsbergen

AWI’s EM-Bird elec­tro­mag­net­ic mea­sur­ing sys­tem mea­sures the thick­ness of sea ice dur­ing low-al­ti­tude flights just 15 me­tres above the sur­face.
At work on board Polar 6
At work on board Po­lar 6
Image 3/6, Credit: Alfred-Wegener-Institut / Esther Horvath (CC-BY 4.0)

At work on board Polar 6

Jörg Brauch­le from the DLR In­sti­tute for Op­ti­cal Sen­sor Sys­tems dur­ing a flight over the Arc­tic on board Po­lar 6.
Measurement of drift ice
Mea­sure­ment of drift ice
Image 4/6, Credit: DLR (CC-BY 3.0)

Measurement of drift ice

High-res­o­lu­tion cam­era view of the Arc­tic drift ice. The aeri­al view of the MACS po­lar cam­era from an al­ti­tude of 100 re­veals the Arc­tic drift ice with a res­o­lu­tion of two cen­time­tres per pix­el. This im­age shows the mea­sure­ment of an ice floe with a length of 15.1 me­tres.
Sensor technology on the Polar 5 research aircraft
Sen­sor tech­nol­o­gy on the Po­lar 5 re­search air­craft
Image 5/6, Credit: DLR (CC-BY 3.0)

Sensor technology on the Polar 5 research aircraft

At­mo­spher­ic re­searchers at DLR are us­ing Po­lar 5 to in­ves­ti­gate the pre­vi­ous­ly un­der­es­ti­mat­ed cli­mate im­pact of clouds over the Arc­tic Ocean.
Arctic clouds
Arc­tic clouds
Image 6/6, Credit: DLR (CC-BY 3.0)

Arctic clouds

Clouds con­tribute sig­nif­i­cant­ly to the rapid warm­ing of the Arc­tic.
  • High-resolution camera observations of the Arctic from the air will close the gap between detailed but very costly ground exploration and large-scale but lower-resolution remote sensing data acquired from space.
  • DLR atmospheric researchers are also investigating Arctic clouds that contribute significantly to the warming of the polar region.
  • The MACS camera system developed by DLR allows images to be acquired in the near-infrared and thermal-infrared parts of the electromagnetic spectrum.
  • Scientists from 20 nations are studying the Arctic over the course of a year as part of the MOSAiC expedition.
  • Focus: Aeronautics, space, climate change, global change, Earth observation.

For the first time since the restrictions imposed due to the Coronavirus pandemic, flights of the Polar 5 and Polar 6 research aircraft are currently taking place from Longyearbyen airport on the island of Spitsbergen to the central Arctic. Both aircraft are operating as part of the MOSAiC expedition led by the Alfred Wegener Institute (AWI) Helmholtz Centre for Polar and Marine Research to study the polar atmosphere and sea ice. The high-resolution Modular Aerial Camera System (MACS) and scientists from the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) are on board. The researchers are particularly interested in how the thickness of the sea ice currently under investigation develops and how changes in the ice sheets can be more easily identified. DLR atmospheric researchers are also involved in the project and want to find out how clouds form over the Arctic Ocean.

From Mount Everest to the Arctic

An earlier version of the MACS camera system has already provided highly detailed, 3D images of ice and snow under the extreme environmental conditions around Mount Everest in the Himalayas. "We have now used this experience to develop an advanced camera instrument for remote sensing of polar regions, which, in addition to a channel for visible light, also has channels for near-infrared and thermal-infrared radiation," says Jörg Brauchle from the DLR Institute for Optical Sensor Systems in Berlin who is flying on board Polar 6. "In this way, we are closing the gap between very costly, detailed exploration on the ground and large-scale, but lower-resolution, remote sensing data acquired from space."

Three spectral channels in comparison
Three spectral channels in comparison
These image show (from left to right) an ice surface in visible light, in near-infrared and in thermal-infrared. The combination of data from different channels can be used to determine, among other things, melting pools or freezing fissures.
Credit: DLR (CC-BY 3.0)

Observations made from the air using MACS make it possible to automatically determine the degree of ice coverage on the water with very high resolution. The optical images also help researchers to determine the roughness of the ice and snow in order to better characterise and classify them both and to better understand the processes at play in sea ice. The near-infrared images are used for the automatic detection of water and ice floes, while the thermal-infrared images allow improved detection of temperature differences between ice and the surrounding environment as well as freezing fissures. Thanks to the high recording rate of four images per second, it is possible to record everything under the aircraft without interruption, even during low flights just 100 metres above the surface. Details as small as two centimetres across can be identified.

Image of an ice surface in thermal infrared (TIR)
Image of an ice surface in thermal infrared (TIR)
The thermal infrared camera resolves details as small as 40 centimetres in size and reveals fissures, which provide information about the dynamics of the ice surface. Image recorded at 84 degrees north, six degrees east.
Credit: DLR (CC-BY 3.0)

The scientists acquired more than 300,000 images with MACS during the first flights at the beginning of September. "Even with the currently very small differences in temperature between water and ice, clear thermal signatures can be identified," Brauchle emphasises. "Even greater temperature differences can be expected during the use of the camera in one of the upcoming winter expeditions, which the powerful thermal sensor will document." The detailed information about the surface ice will help to improve climate models and serve as a training basis for new AI methods that will be used to evaluate the large number of images. In addition to the documentation of the surface properties of the sea ice, an electromagnetic measuring system (EM-Bird) from AWI on board Polar 6 is being used to measure sea ice thickness.

Droplet size distribution and analyses of ice crystal shapes for cloud research

While Polar 6 measures the sea ice in the Arctic Ocean, the Polar 5 crew is concentrating on studying the atmosphere and clouds above the Arctic Ocean. Previous studies have shown that clouds contribute significantly to the rapid warming of the Arctic region. However, modern atmospheric models have so far underestimated the influence of clouds and still simulate it too imprecisely. For this reason, the team of researchers from AWI, DLR and the universities of Leipzig, Bremen, Cologne, Mainz, and Clermont Auvergne are studying the air masses over the Arctic Ocean on a large scale and investigating in detail all the factors relevant to cloud formation. "On board Polar 5 we are measuring microphysical cloud properties such as droplet size distribution, phase, ice and liquid water content, and the shapes of ice crystals," explains Valerian Hahn from the DLR Institute of Atmospheric Physics. "Another main focus is on Arctic mixed-phase clouds," adds Manuel Moser from the same institute. As they make their measurements of the Arctic air, the researchers are also following the route previously taken by the German research icebreaker, Polarstern, as part of the MOSAiC campaign.

About MOSAiC

In the context of MOSAiC, experts from 20 countries are researching the Arctic for an entire year. To make this possible, from autumn 2019 to autumn 2020 the German research icebreaker Polarstern will drift through the Arctic Ocean, trapped in the ice. MOSAiC is coordinated by the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI). To ensure that this unparalleled project is a success and yields as much valuable data as possible, more than 80 institutes have pooled their resources in a research consortium. The expedition budget is more than140 million euro.

For news straight from the Arctic, check out the MOSAiC channels on twitter and Instagram under the hashtags #MOSAiCexpedition, #Arctic and #icedrift

You can find further information on the expedition at: https://mosaic-expedition.org/

Or you can use the MOSAiC Web-App to follow Polarstern's drift route and events on site, live: https://follow.mosaic-expedition.org/

DLR is also represented on board Polarstern with an experimental measurement technology studying navigation signals in the Arctic region as part of the MOSAiC campaign.

Contact
  • Falk Dambowsky
    Ed­i­tor
    Ger­man Aerospace Cen­ter (DLR)
    Me­dia Re­la­tions
    Telephone: +49 2203 601-3959
    Fax: +49 2203 601-3249
    Linder Höhe
    51147 Cologne
    Contact
  • Jörg Brauchle
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Op­ti­cal Sen­sor Sys­tems
    Rutherfordstraße 2
    12489 Berlin-Adlershof
    Contact
  • Valerian Hahn
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of At­mo­spher­ic Physics
    Cloud Physics
    Münchener Straße 20
    82234 Oberpfaffenhofen
    Contact
  • Manuel Moser
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of At­mo­spher­ic Physics
    Cloud Physics
    Münchener Straße 20
    82234 Oberpfaffenhofen
    Contact
  • Sebastian Grote
    Al­fred-We­gen­er-In­sti­tut (AWI)
    Com­mu­ni­ca­tions and Me­dia Re­la­tions
    Telephone: +49 471 4831-2006

    Contact

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