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ASI |  Italian space agency

ASI | Italian space agency

Electronic “eyes” on the glaciers in Golfo in Amundsen NileWest Antarctica: are the moons of the constellation COSMO-SkyMed DelItalian space agency e Tandem-X From DLR (German Space Agency), who monitored the health of this region of the “White Continent” using their own Synthetic aperture radar sensors (SAR).

The results of the survey have recently been clarified studio Posted in natural earth sciences (Element: “Rapid glacier retreat rates observed in West Antarctica”). Research is the result of collaboration between scientists and engineersUniversity of HoustonDelUniversity of Irvine in California, DelGrenoble University In France, fromAround Based on DLR.

Using a specific analysis method, called SAR . interferometer, on data COSMO-SkyMed The research team was able to measure reverse speed From Glacier water lines For the first time it was possible to measure this parameter of a glacier in Amundsen Bay, which reached values ​​u200bu200bof 11.7 km / year.

“A rapid retreat of 11.7 km/year over a period of 3 months was observed on a glacier called Bob,” he said. Pietro Melillo, the first author of the article and currently a professor at the University of Houston – thanks to a new generation of search and rescue satellites, we have been able to observe the Bob, Smith and Kohler glaciers in West Antarctica that in recent years have shown Faster decline rates than expected.”

“The scientific results of this relief can only be achieved thanks to highly advanced technologies and international cooperation – he notes Luigi Dini, co-author of the article and ASI technologist – for this study, one of the properties that makes our group of 5 COSMO-SkyMed satellites unique in the world panorama was used, namely the ability to obtain Two high-resolution radar images, with the same radiomic and geometric properties, are only a day apart from each other and repeat these acquisitions every two weeks for an extended period of time, three years in the case study.”

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“These repeated observations from space are fundamental to understanding Short term dynamics of a glacier And how they behave on short time scales – continues Milillo – in the past we had to wait several years to retrieve data useful for such analysis and we could only observe long-term trends. Now we can check Glaciers are retreating on a monthly basis We are able to obtain a new level of detail that will help improve glacier models and thus improve or estimate sea level rise. “

The new generation of synthetic aperture radar It allows the discovery of a new class of physical phenomena that occur along the so-called “water line” or grounding line, the The line between solid ice on the mainland and ice floating at sea, and sheds new light on the short-time dynamics of glaciers. In particular, in this study, it was possible to analyze both measurements of differences in surface heights around the waterlines of the Bob, Smith and Kohler glaciers in Amudsen Bay and their retreat velocity on a bimonthly basis.

We use repeated observation to describe water line drain Caused by tides, which we’ve discovered, can be on the order of several kilometers per tidal cycle – explains Milillo – so far the waterline in the Kohler glacier should have swung without apparent receding over the years, while this study shows a gradual retreat of the waterline Kohler Glacier measures its own line periodic migration Caused by tidal cycles. At the current rate, the teacher concludes, the Smith and Koehler glaciers will melt within the next 15 years. This melting will connect the ice shelf cavities and change the ocean circulation under the Dotson Ice Shelf.

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Digital models of ice cover are still incomplete and do not contain the physics needed to represent these types of events, which means that these models may underestimate the rate at which glaciers are melting. the Glaciers Bob, Smith and Koehler They control a drainage area with a volume of drift ice equivalent to a global sea level rise of 6 cm. However, the same physical processes that drive them back down are at work on the nearby Thwaites and Pine Island glaciers which could contribute to the increased importance of Global sea level rise 1.2 meters and destabilize the rest of West Antarctica. Understand the physical processes driving the rapid decline of Bob, Smith and Kohler, particularly the extent of ice melting grounding line, it is therefore necessary to explain and reproduce the observed withdrawal rates.

The second generation of the new generation of Cosmo-SkyMed satellites will also be launched at the end of January, bringing the number of operating satellites in the constellation to six. This will allow, on the one hand, to give continuity to the measures to monitor the glaciers of Antarctica and on the other hand to carry out analyzes, which are not possible with satellites of the old generation, using the new and innovative capabilities of satellites of the second generation.

Above: Pope Glacier and in the background Mount Murphy on November 8, 2016 (Credits: NASA Operation Ice Bridge 2016)