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Axel Schweiger

Senior Principal Scientist

Email

axel@apl.washington.edu

Phone

206-543-1312

Research Interests

Remote Sensing, Arctic Climatology, Systems Management

Biosketch

Dr. Schweiger's 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

Education

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

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

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

Projects

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.

 

Videos

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.

Publications

2000-present and while at APL-UW

Recent upper Arctic Ocean warming expedited by summertime atmospheric processes

Li, Z., Q.H. Ding, M. Steele, and A. Schweiger, "Recent upper Arctic Ocean warming expedited by summertime atmospheric processes," Nat. Commun., 13, doi:10.1038/s41467-022-28047-8, 2022.

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18 Jan 2022

Low-frequency internal atmospheric variability accounts for about one quarter of observed Arctic Ocean warming over the past four decades and 60% of the accelerated warming from 2000 to 2018.

The observed upper (0–-50 m) Arctic Ocean warming since 1979 has been primarily attributed to anthropogenically driven changes in the high latitudes. Here, using both observational and modeling analyses, we demonstrate that a multiyear trend in the summertime large-scale atmospheric circulation, which we ascribe to internal variability, has played an important role in upper ocean warming in summer and fall over the past four decades due to sea ice-albedo effect induced by atmospheric dynamics. Nudging experiments in which the wind fields are constrained toward the observed state support this mechanism and suggest that the internal variability contribution to recent upper Arctic Ocean warming accounts for up to one quarter of warming over the past four decades and up to 60% of warming from 2000 to 2018. This suggests that climate models need to replicate this important internal process in order to realistically simulate Arctic Ocean temperature variability and trends.

Accelerated sea ice loss in the Wandel Sea points to a change in the Arctic's Last Ice Area

Schweiger, A.J., M. Steele, J. Zhang, G.W.K. Moore, and K.L. Laidre, "Accelerated sea ice loss in the Wandel Sea points to a change in the Arctic's Last Ice Area," Comm. Earth Environ., 2, doi:, 2021.

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1 Jul 2021

The Arctic Ocean's Wandel Sea is the easternmost sector of the Last Ice Area, where thick, old sea ice is expected to endure longer than elsewhere. Nevertheless, in August 2020 the area experienced record-low sea ice concentration. Here we use satellite data and sea ice model experiments to determine what caused this record sea ice minimum. In our simulations there was a multi-year sea-ice thinning trend due to climate change. Natural climate variability expressed as wind-forced ice advection and subsequent melt added to this trend. In spring 2020, the Wandel Sea had a mixture of both thin and — unusual for recent years — thick ice, but this thick ice was not sufficiently widespread to prevent the summer sea ice concentration minimum. With continued thinning, more frequent low summer sea ice events are expected. We suggest that the Last Ice Area, an important refuge for ice-dependent species, is less resilient to warming than previously thought.

Evidence of an increasing role of ocean heat in Arctic winter sea ice growth

Ricker, R., F. Kauker, A. Schweiger, S. Hendricks, J. Zhang, and S. Paul, "Evidence of an increasing role of ocean heat in Arctic winter sea ice growth," J. Clim., 34, 5215-5227, doi:10.1175/JCLI-D-20-0848.1, 2021.

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1 Jul 2021

We investigate how sea ice decline in summer and warmer ocean and surface temperatures in winter affect sea ice growth in the Arctic. Sea ice volume changes are estimated from satellite observations during winter from 2002 to 2019 and partitioned into thermodynamic growth and dynamic volume change. Both components are compared to validated sea ice-ocean models forced by reanalysis data to extend observations back to 1980 and to understand the mechanisms that cause the observed trends and variability. We find that a negative feedback driven by the increasing sea ice retreat in summer yields increasing thermodynamic ice growth during winter in the Arctic marginal seas eastward from the Laptev Sea to the Beaufort Sea. However, in the Barents and Kara Seas, this feedback seems to be overpowered by the impact of increasing oceanic heat flux and air temperatures, resulting in negative trends in thermodynamic ice growth of –2 km3month-1yr-1 on average over 2002–2019 derived from satellite observations.

More Publications

In The News

Fact check: NASA did not deny warming or say polar ice has increased since 1979

USA Today, Kate Petersen

NASA researchers have documented the loss of trillions of tons of ice from Earth's poles due to human-driven climate change. Citing published reports from the Polar Science Center and other sources, popular social media memes claiming an increase in polar ice since 1979 are swatted down.

21 Jan 2022

Arctic's 'last ice area' may be less resistant to global warming

The New York Times, Henry Fountain

The region, which could provide a last refuge for polar bears and other Arctic wildlife that depends on ice, is not as stable as previously thought, according to a new study.

1 Jul 2021

Arctic's 'last ice area' shows earlier-than-expected melt

Associated Press, Seth Borenstein

Part of the Arctic is nicknamed the 'Last Ice Area,' because floating sea ice there is usually so thick that it’s likely to withstand global warming for decades. So, scientists were shocked last summer when there was suddenly enough open water for a ship to pass through.

1 Jul 2021

More News Items

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