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Ian Joughin

Senior Principal Engineer

Affiliate Professor, Earth and Space Sciences

Email

ian@apl.uw.edu

Phone

206-221-3177

Biosketch

Ian Joughin continues his pioneering research into the use of differential SAR interferometry for the estimation of surface motion and topography of ice sheets. He combines the remote sensing with field work and modeling to solve ice dynamics problems. Solving the problems helps him understand the mass balance of the Greenland and Antarctic Ice Sheets in response to climate change.

In addition to polar research, he also contributed to the development of algorithms that were used to mosaic data for the near-global map of topography from the Shuttle Radar Topography Mission (SRTM).

Department Affiliation

Polar Science Center

Education

B.S. Electrical Engineering, University of Vermont, 1986

M.S. Electrical Engineering, University of Vermont, 1990

Ph.D. Electrical Engineering, University of Washington, 1995

Publications

2000-present and while at APL-UW

Observing traveling waves in glaciers with remote sensing: new flexible time series methods and application to Sermeq Kujalleq (Jakobshavn Isbræ), Greenland

Riel, B., B. Minchew, and I. Joughin, "Observing traveling waves in glaciers with remote sensing: new flexible time series methods and application to Sermeq Kujalleq (Jakobshavn Isbræ), Greenland," Cryosphere, 15, 407-439, doi:10.5194/tc-15-407-2021, 2021.

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28 Jan 2021

The recent influx of remote sensing data provides new opportunities for quantifying spatiotemporal variations in glacier surface velocity and elevation fields. Here, we introduce a flexible time series reconstruction and decomposition technique for forming continuous, time-dependent surface velocity and elevation fields from discontinuous data and partitioning these time series into short- and long-term variations. The time series reconstruction consists of a sparsity-regularized least-squares regression for modeling time series as a linear combination of generic basis functions of multiple temporal scales, allowing us to capture complex variations in the data using simple functions. We apply this method to the multitemporal evolution of Sermeq Kujalleq (Jakobshavn Isbræ), Greenland. Using 555 ice velocity maps generated by the Greenland Ice Mapping Project and covering the period 2009–2019, we show that the amplification in seasonal velocity variations in 2012–2016 was coincident with a longer-term speedup initiating in 2012. Similarly, the reduction in post-2017 seasonal velocity variations was coincident with a longer-term slowdown initiating around 2017. To understand how these perturbations propagate through the glacier, we introduce an approach for quantifying the spatially varying and frequency-dependent phase velocities and attenuation length scales of the resulting traveling waves. We hypothesize that these traveling waves are predominantly kinematic waves based on their long periods, coincident changes in surface velocity and elevation, and connection with variations in the terminus position. This ability to quantify wave propagation enables an entirely new framework for studying glacier dynamics using remote sensing data.

Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica

Hoffman, A.O., K. Christianson, D. Shapero, B.E. Smith, and I. Joughin, "Brief communication: Heterogenous thinning and subglacial lake activity on Thwaites Glacier, West Antarctica," Cryosphere, 14, 4603-4609, doi:10.5194/tc-14-4603-2020, 2020.

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18 Dec 2020

A system of subglacial lakes drained on Thwaites Glacier from 2012-2014. To improve coverage for subsequent drainage events, we extended the elevation and icevelocity time series on Thwaites Glacier through austral winter 2019. These new observations document a second drainage cycle in 2017/18 and identified two new lake systems located in the western tributaries of Thwaites and Haynes glaciers. In situ and satellite velocity observations show temporary < 3% speed fluctuations associated with lake drainages. In agreement with previous studies, these observations suggest that active subglacial hydrology has little influence on thinning and retreat of Thwaites Glacier on decadal to centennial timescales.

Toward a universal glacier slip law

Minchew, B., and I. Joughin, "Toward a universal glacier slip law," Science, 368, 29-30, doi:10.1126/science.abb3566, 2020.

3 Apr 2020

More Publications

In The News

Antarctic'as ice sheet is melting 3 times faster than before

Associate Press, Seth Borenstein

The melting of Antarctica is accelerating at an alarming rate, with about 3 trillion tons of ice disappearing since 1992, an international team of ice experts said in a new study.

14 Jun 2018

Hidden lakes drain below West Antarctica's Thwaites Glacier

UW News and Information, Hannah Hickey

Thwaites Glacier on the edge of West Antarctica is one of the planet’s fastest-moving glaciers. Research shows that it is sliding unstoppably into the ocean, mainly due to warmer seawater lapping at its underside.

8 Feb 2017

Satellite system tracks glaciers' flow in real time

Nature News, Jeff Tollefson

The Global Land Ice Velocity Extraction project (GoLIVE) is the first to provide scientists with regular, semi-automated measurements of ice movement across the entire world. The Landsat 8 satellite covers the planet every 16 days.

16 Dec 2016

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