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Axel Schweiger

Chair, Polar Science Center & Senior Principal Scientist

Email

axel@apl.washington.edu

Phone

206-543-1312

Research Interests

Remote Sensing, Arctic Climatology, Systems Management

Biosketch

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

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

How tropical Pacific surface cooling contributed to accelerated sea ice melt from 2007 to 2012 as ice is thinned by anthropogenic forcing

Baxter, I., Q. Ding, A. Schweiger, M. L'Heureux, S. Baxter, T. Wang, Q. Zhang, K. Harnos, B. Markle, D. Topal, and J. Lu, "How tropical Pacific surface cooling contributed to accelerated sea ice melt from 2007 to 2012 as ice is thinned by anthropogenic forcing," J. Clim., 32, 8583-8602, doi:10.1175/JCLI-D-18-0783.1, 2019.

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1 Dec 2019

Over the past 40 years, the Arctic sea ice minimum in September has declined. The period between 2007 and 2012 showed accelerated melt contributed to the record minima of 2007 and 2012. Here, observational and model evidence shows that the changes in summer sea ice since the 2000s reflect a continuous anthropogenically forced melting masked by interdecadal variability of Arctic atmospheric circulation. This variation is partially driven by teleconnections originating from sea surface temperature (SST) changes in the east-central tropical Pacific via a Rossby wave train propagating into the Arctic [herein referred to as the Pacific–Arctic teleconnection (PARC)], which represents the leading internal mode connecting the pole to lower latitudes. This mode has contributed to accelerated warming and Arctic sea ice loss from 2007 to 2012, followed by slower declines in recent years, resulting in the appearance of a slowdown over the past 11 years. A pacemaker model simulation, in which we specify observed SST in the tropical eastern Pacific, demonstrates a physically plausible mechanism for the PARC mode. However, the model-based PARC mechanism is considerably weaker and only partially accounts for the observed acceleration of sea ice loss from 2007 to 2012. We also explore features of large-scale circulation patterns associated with extreme melting periods in a long (1800 yr) CESM preindustrial simulation. These results further support that remote SST forcing originating from the tropical Pacific can excite significant warm episodes in the Arctic. However, further research is needed to identify the reasons for model limitations in reproducing the observed PARC mode featuring a cold Pacific–warm Arctic connection.

Spatiotemporal variability of sea ice in the Arctic's last ice area

Moore, G.W.K., A. Schweiger, J. Zhang, and M. Steele, "Spatiotemporal variability of sea ice in the Arctic's last ice area," Geophys. Res. Lett., 46, 11,237-11,243, doi:10.1029/2019GL083722, 2019.

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28 Oct 2019

The Arctic Ocean's oldest and thickest sea ice lies along the ~2,000 km arc from the western Canadian Arctic Archipelago to the northern coast of Greenland. Climate models suggest that this region will be the last to lose its perennial ice cover, thus providing an important refuge for ice‐dependent species. However, remarkably little is known about the climate or characteristics of the sea ice in this remote and inhospitable region. Here, we use the Pan‐Arctic Ice Ocean Modeling and Assimilation System model to show that the ice cover in the region is very dynamic, with changes occurring at a rate twice that of the Arctic Ocean as a whole. However, there are some differences in the changing nature of the ice cover between the eastern and western regions of the Last Ice Area, which include different timing of the annual minimum in ice thickness as well as distinct ice motion patterns associated with ice thickness extrema.

Arctic sea ice volume variability over 1901–2010: A model-based reconstruction

Schweiger, A.J., K.R. Wood, and J. Zhang, "Arctic sea ice volume variability over 1901–2010: A model-based reconstruction," J. Clim., 32, 4731-4753, doi:10.1175/JCLI-D-19-0008.1, 2019.

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1 Aug 2019

PIOMAS-20C, an Arctic sea ice reconstruction for 1901–2010, is produced by forcing the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) with ERA-20C atmospheric data. ERA-20C performance over Arctic sea ice is assessed by comparisons with measurements and data from other reanalyses. ERA-20C performs similarly with respect to the annual cycle of downwelling radiation, air temperature, and wind speed compared to reanalyses with more extensive data assimilation such as ERA-Interim and MERRA. PIOMAS-20C sea ice thickness and volume are then compared with in situ and aircraft remote sensing observations for the period of ~1950–2010. Error statistics are similar to those for PIOMAS. We compare the magnitude and patterns of sea ice variability between the first half of the twentieth century (1901–40) and the more recent period (1980–2010), both marked by sea ice decline in the Arctic. The first period contains the so-called early-twentieth-century warming (ETCW; ~1920–40) during which the Atlantic sector saw a significant decline in sea ice volume, but the Pacific sector did not. The sea ice decline over the 1979–2010 period is pan-Arctic and 6 times larger than the net decline during the 1901–40 period. Sea ice volume trends reconstructed solely from surface temperature anomalies are smaller than PIOMAS-20C, suggesting that mechanisms other than warming, such as changes in ice motion and deformation, played a significant role in determining sea ice volume trends during both periods.

More Publications

In The News

Century-old ship logs show how much ice the Arctic has lost

Popular Science, Marlene Cimons

By diving into archives, scientists confirmed that floes are melting faster than ever before.

19 Sep 2019

Century-old ship logs reveal extent of today's drastic Arctic melt

Mashable, Mark Kaufman

The often-frigid, ice-clad Arctic remains a harsh world. But in the early 1900s, there was substantially more ice than there is today. New research used old shipping logs, meticulously kept by mariners often each hour, to extend the Arctic sea ice record back 110 years, over seven decades before satellites began regularly monitoring the high north.

10 Aug 2019

More than 100 years of Arctic sea ice volume reconstructed with help from historic ships’ logbooks

UW News, Hannah Hickey

Our knowledge of the dwindling sea ice coverage in the Arctic Ocean comes mostly through satellites, which since 1979 have imaged the sea ice from above. The University of Washington’s Pan-Arctic Ice Ocean and Modeling System, or PIOMAS, is a leading tool for gauging the thickness of that ice. Until now that system has gone back only as far as 1979.

8 Aug 2019

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