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Axel Schweiger

Chair, Polar Science Center & Senior Principal Scientist





Research Interests

Remote Sensing, Arctic Climatology, Systems Management


Dr. Schweiger is the current chair of the Polar Science Center. His research focuses on sea ice, clouds, and radiation in the Arctic. He is using satellite data, models, and in-situ observations to improve our understanding of sea ice and cloud variability. He has developed the PSC Arctic Ice Volume Page, which provides monthly updated total Arctic Ice Volume estimates based on the PIOMAS model. He has worked on the validation, improvements, and applications of PIOMAS to a variety of problems.

He is a an investigator in the Seasonal Ice Zone Reconnaissance Survey Project (SIZRS) that utilizes US-Coast Guard Arctic Domain Awareness flights make Atmospheric and Oceanographic measurements of the seasonal ice zone of the Beaufort Sea and targets the improved understanding of the changes in the Arctic system as sea ice retreats.

He has worked on algorithm development for the retrieval of clouds and atmospheric profiles and generated the the TOVS Polar Pathfinder data set, a 20-year data set of polar temperature, humidity profiles and cloud information. Previous research includes work on microwave-based sea ice concentration algorithms and the application of artificial intelligence methods to remote sensing problems. Dr. Schweiger has been with the Polar Science Center since 1992.

Department Affiliation

Polar Science Center


B.A. Geography & English, Universitat Erlangen, 1984

M.S. Geography, University of Colorado, Boulder, 1987

Ph.D. Geography, University of Colorado, Boulder, 1992


Arctic Surface Air Temperatures for the Past 100 Years

Accurate fields of Arctic surface air temperature (SAT) are needed for climate studies, but a robust gridded data set of SAT of sufficient length is not available over the entire Arctic. We plan to produce authoritative SAT data sets covering the Arctic Ocean from 1901 to present, which will be used to better understand Arctic climate change.


The Fate of Summertime Arctic Ocean Heating: A Study of Ice-Albedo Feedback on Seasonal to Interannual Time Scales

The main objective of this study is to determine the fate of solar energy absorbed by the arctic seas during summer, with a specific focus on its impact on the sea ice pack. Investigators further seek to understand the fate of this heat during the winter and even beyond to the following summer. Their approach is use a coupled sea ice–ocean model forced by atmospheric reanalysis fields, with and without assimilation of satellite-derived ice and ocean variables. They are also using satellite-derived ocean color data to help determine light absorption in the upper ocean.



Arctic Sea Ice Extent and Volume Follow Long-term Trend

In mid-September Arctic sea ice reached its minimum extent and volume. There are annual fluctuations — 2012 was a record low for both measures — but reports of a recent 'rebound' are short-sighted. Axel Schweiger, Chair of the APL-UW Polar Science Center, shows that the downward long-term trend is clear.

6 Nov 2015

Arctic Sea Ice Extent and Volume Dip to New Lows

By mid-September, the sea ice extent in the Arctic reached the lowest level recorded since 1979 when satellite mapping began.

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15 Oct 2012

APL-UW polar oceanographers and climatologists are probing the complex ice–ocean–atmosphere system through in situ and remote sensing observations and numerical model simulations to learn how and why.

Focus on Arctic Sea Ice: Current and Future States of a Diminished Sea Ice Cover

APL-UW polar scientists are featured in the March edition of the UW TV news magazine UW|360, where they discuss their research on the current and future states of a diminished sea ice cover in the Arctic.

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7 Mar 2012

The dramatic melting of Arctic sea ice over the past several summers has generated great interest and concern in the scientific community and among the public. Here, APL-UW polar scientists present their research on the current state of Arctic sea ice. A long-term, downward trend in sea ice volume is clear.

They also describe how the many observations they gather are used to improve computer simulations of global climate that, in turn, help us to asses the impacts of a future state of diminished sea ice cover in the Arctic.

This movie presentation was first seen on the March 2012 edition of UW|360, the monthly University of Washington Television news magazine.


2000-present and while at APL-UW

What caused the remarkable February 2018 North Greenland polynya?

Moore, G.W.K., A. Schweiger, J. Zhang, and M. Steele, "What caused the remarkable February 2018 North Greenland polynya?" Geophys. Res. Lett., EOR, doi:10.1029/2018GL080902, 2018.

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6 Dec 2018

During late February and early March 2018, an unusual polynya was observed off the north coast of Greenland. This period was also notable for the occurrence of a sudden stratospheric warming. Here we use satellite and in situ data, a reanalysis and an ice‐ocean model to document the evolution of the polynya and its synoptic forcing. We show that its magnitude was unprecedented and that it was associated with the transient response to the sudden stratospheric warming leading to anomalous warm southerly flow in north Greenland. Indeed, regional wind speeds and temperatures were the highest during February going back to the 1960s. There is evidence that the thinning sea ice has increased its wind‐driven mobility. However, we show that the polynya would have developed under thicker ice conditions representative of the late 1970s and that even with the predicted trend toward thinner sea ice, it will only open during enhanced southerly flow.

Melt pond conditions on declining Arctic sea ice over 1979–2016: Model development, validation, and results

Zhang, J., A. Schwieger, M. Webster, B. Light, M. Steele, C. Ashjian, R. Campbell, and Y. Spitz, "Melt pond conditions on declining Arctic sea ice over 1979–2016: Model development, validation, and results," J. Geophys. Res., 123, 7983-8003, doi:10.1029/2018JC014298, 2018.

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1 Nov 2018

A melt pond (MP) distribution equation has been developed and incorporated into the Marginal Ice‐Zone Modeling and Assimilation System to simulate Arctic MPs and sea ice over 1979–2016. The equation differs from previous MP models and yet benefits from previous studies for MP parameterizations as well as a range of observations for model calibration. Model results show higher magnitude of MP volume per unit ice area and area fraction in most of the Canada Basin and the East Siberian Sea and lower magnitude in the central Arctic. This is consistent with Moderate Resolution Imaging Spectroradiometer observations, evaluated with Measurements of Earth Data for Environmental Analysis (MEDEA) data, and closely related to top ice melt per unit ice area. The model simulates a decrease in the total Arctic sea ice volume and area, owing to a strong increase in bottom and lateral ice melt. The sea ice decline leads to a strong decrease in the total MP volume and area. However, the Arctic‐averaged MP volume per unit ice area and area fraction show weak, statistically insignificant downward trends, which is linked to the fact that MP water drainage per unit ice area is increasing. It is also linked to the fact that MP volume and area decrease relatively faster than ice area. This suggests that overall the actual MP conditions on ice have changed little in the past decades as the ice cover is retreating in response to Arctic warming, thus consistent with the Moderate Resolution Imaging Spectroradiometer observations that show no clear trend in MP area fraction over 2000–2011.

Collapse of the 2017 winter Beaufort high: A response to thinning sea ice?

Moore, G.W.K., A. Schweiger, J. Zhang, and M. Steele, "Collapse of the 2017 winter Beaufort high: A response to thinning sea ice?," Geophys. Res. Lett., 45, 2860-2869, doi:10.1002/2017GL076446, 2018.

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28 Mar 2018

The winter Arctic atmosphere is under the influence of two very different circulation systems: extratropical cyclones travel along the primary North Atlantic storm track from Iceland toward the eastern Arctic, while the western Arctic is characterized by a quasi‐stationary region of high pressure known as the Beaufort High. The winter (January through March) of 2017 featured an anomalous reversal of the normally anticyclonic surface winds and sea ice motion in the western Arctic. This reversal can be traced to a collapse of the Beaufort High as the result of the intrusion of low‐pressure systems from the North Atlantic, along the East Siberian Coast, into the Arctic Basin. Thin sea ice as the result of an extremely warm autumn (October through December) of 2016 contributed to the formation of an anomalous thermal low over the Barents Sea that, along with a northward shift of the tropospheric polar vortex, permitted this intrusion. The collapse of the Beaufort High during the winter of 2017 was associated with simultaneous 2‐sigma sea level pressure, surface wind, and sea ice circulation anomalies in the western Arctic. As the Arctic sea ice continues to thin, such reversals may become more common and impact ocean circulation, sea ice, and biology.

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In The News

February's big patch of open water off Greenland? Not global warming, says new analysis

UW News, Hannah Hickey

In February 2018, a vast expanse of open water appeared in the sea ice above Greenland, a region that normally has sea ice well into the spring. The big pool of open water in the middle of the ice, known as a polynya, was a scientific puzzle.

18 Dec 2018

The Arctic Ocean has lost 95 percent of its oldest ice — a startling sign of what's to come

The Washington Post, Chris Mooney

Over the past three decades of global warming, the oldest and thickest ice in the Arctic has declined by a stunning 95 percent, according the National Oceanic and Atmospheric Administration’s annual Arctic Report Card. "We've lost about half of the extent, we've lost half of the thickness, and if you multiply these two things, we've lost 75 percent of the September sea ice," Axel Schweiger said.

11 Dec 2018

Arctic sea ice dwindles to record low for winter

CBS News

The frigid top of the Earth just set yet another record for low levels of sea ice in what scientists say is just the latest signal of an overheating world.

22 Mar 2017

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Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center