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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

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.

Low‐level and surface wind jets near sea ice edge in the Beaufort Sea in late autumn

Liu, Z., and A. Schwieger, "Low‐level and surface wind jets near sea ice edge in the Beaufort Sea in late autumn," J. Geophys. Res., 124, 6873-6891, doi:10.1029/2018JD029770, 2019.

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16 Jul 2019

Low‐level wind jets (LLJs) and strong surface winds are frequently observed near the sea ice edge in the presence of strong thermal contrast between open water and sea ice. Two LLJ cases near the sea ice edge in the Beaufort Sea are examined using dropsonde observations made from Seasonal Ice Zone Reconnaissance Survey flights. Ensembles of Polar Weather Research and Forecast simulations with and without sea ice demonstrate the contribution of the surface thermal contrast to the boundary layer structure, the LLJ, and surface ice edge jets. Because the surface temperature contrast only influences the lower most hundreds of meters in the atmospheric boundary layer, its contribution to the temperature gradient and wind speed at the level of the LLJ is limited. The sea ice does strengthen the LLJ by extending the LLJ northward over sea ice and increasing the maximum LLJ wind speeds by up to 13% and as much as 29% further north at a lower altitude. However, the primary reason for the observed strong winds in these two cases are the synoptic interactions between anticyclones and approaching cyclones. The effect of the surface thermal contrast on surface winds is controlled by a separate mechanism. The cold and stable boundary layer over sea ice prevents the momentum transport from the LLJ to the surface. This leads to weaker surface winds over sea ice and confines the strong surface winds close to the sea ice edge. This mechanism contributes to the frequent occurrence of the surface "ice edge jets."

Fingerprints of internal drivers of Arctic sea ice loss in observations and model simulations

Ding, Q., A. Schweiger, and 11 others, "Fingerprints of internal drivers of Arctic sea ice loss in observations and model simulations," Nature Geosci., 12, 28-33, doi:10.1038/s41561-018-0256-8, 2019.

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1 Jan 2019

The relative contribution and physical drivers of internal variability in recent Arctic sea ice loss remain open questions, leaving up for debate whether global climate models used for climate projection lack sufficient sensitivity in the Arctic to climate forcing. Here, through analysis of large ensembles of fully coupled climate model simulations with historical radiative forcing, we present an important internal mechanism arising from low-frequency Arctic atmospheric variability in models that can cause substantial summer sea ice melting in addition to that due to anthropogenic forcing. This simulated internal variability shows a strong similarity to the observed Arctic atmospheric change in the past 37 years. Through a fingerprint pattern matching method, we estimate that this internal variability contributes to about 40–50% of observed multi-decadal decline in Arctic sea ice. Our study also suggests that global climate models may not actually underestimate sea ice sensitivities in the Arctic, but have trouble fully replicating an observed linkage between the Arctic and lower latitudes in recent decades. Further improvements in simulating the observed Arctic–global linkage are thus necessary before the Arctic’s sensitivity to global warming in models can be quantified with confidence.

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

More News Items

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
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