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Anthony Arendt

Research Scientist/Engineer - Principal





Department Affiliation

Polar Science Center


B.S. Earth & Atmospheric Sciences, University of Alberta, 1995

M.S. Earth & Atmospheric Sciences, University of Alberta, 1997

Ph.D. Geophysics, University of Alaska, 2006


2000-present and while at APL-UW

The challenge of monitoring glaciers with extreme altitudinal range: mass-balance reconstruction for Kahiltna Glacier, Alaska

Young, J.C., A. Arendt, R. Hock, E. Pettit, "The challenge of monitoring glaciers with extreme altitudinal range: mass-balance reconstruction for Kahiltna Glacier, Alaska," J. Glaciol., 64, 75-88, doi:10.1017/jog.2017.80, 2018.

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1 Feb 2018

Glaciers spanning large altitudinal ranges often experience different climatic regimes with elevation, creating challenges in acquiring mass-balance and climate observations that represent the entire glacier. We use mixed methods to reconstruct the 1991–2014 mass balance of the Kahiltna Glacier in Alaska, a large (503 km2) glacier with one of the greatest elevation ranges globally (264–6108 m a.s.l.). We calibrate an enhanced temperature index model to glacier-wide mass balances from repeat laser altimetry and point observations, finding a mean net mass-balance rate of –0.74 m w.e. a-1 (± σ = 0.04, std dev. of the best-performing model simulations). Results are validated against mass changes from NASA's Gravity Recovery and Climate Experiment (GRACE) satellites, a novel approach at the individual glacier scale. Correlation is strong between the detrended model- and GRACE-derived mass change time series (R2 = 0.58 and p << 0.001), and between summer (R2 = 0.69 and p = 0.003) and annual (R2 = 0.63 and p = 0.006) balances, lending greater confidence to our modeling results. We find poor correlation, however, between modeled glacier-wide balances and recent single-stake monitoring. Finally, we make recommendations for monitoring glaciers with extreme altitudinal ranges, including characterizing precipitation via snow radar profiling.

Hydrologic impacts of changes in climate and glacier extent in the Gulf of Alaska watershed

Beamer, J.P., D.F. Hill, D. McGrath, A. Arendt, and C. Kienholz, "Hydrologic impacts of changes in climate and glacier extent in the Gulf of Alaska watershed," Water Resour. Res., 53, 7502-7520, doi:10.1002/2016WR020033, 2017.

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1 Sep 2017

High-resolution regional-scale hydrologic models were used to quantify the response of late 21st century runoff from the Gulf of Alaska (GOA) watershed to changes in regional climate and glacier extent. NCEP Climate Forecast System Reanalysis data were combined with five Coupled Model Intercomparison Project Phase 5 general circulation models (GCMs) for two representative concentration pathway (RCP) scenarios (4.5 and 8.5) to develop meteorological forcing for the period 2070–2099. A hypsographic model was used to estimate future glacier extent given assumed equilibrium line altitude (ELA) increases of 200 and 400 m. GCM predictions show an increase in annual precipitation of 12% for RCP 4.5 and 21% for RCP 8.5, and an increase in annual temperature of 2.5°C for RCP 4.5 and 4.3°C for RCP 8.5, averaged across the GOA. Scenarios with perturbed climate and glaciers predict annual GOA-wide runoff to increase by 9% for RCP4.5/ELA200 case and 14% for the RCP8.5/ELA400 case. The glacier runoff decreased by 14% for RCP4.5/ELA200 and by 34% for the RCP8.5/ELA400 case. Intermodel variability in annual runoff was found to be approximately twice the variability in precipitation input. Additionally, there are significant changes in runoff partitioning and increases in snowpack runoff are dominated by increases in rain-on-snow events. We present results aggregated across the entire GOA and also for individual watersheds to illustrate the range in hydrologic regime changes and explore the sensitivities of these results by independently perturbing only climate forcings and only glacier cover.

Hypsometric control on glacier mass balance sensitivity in Alaska and northwest Canada

McGrath, D., L. Sass, S. O'Neel, A. Arendt, and C. Kienholz, "Hypsometric control on glacier mass balance sensitivity in Alaska and northwest Canada," Earth's Future, 5, 324-336, doi:10.1002/2016EF000479, 2017.

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1 Mar 2017

Glacier hypsometry provides a first-order approach for assessing a glacier's response to climate forcings. We couple the Randolph Glacier Inventory to a suite of in situ observations and climate model output to examine potential change for the ~27,000 glaciers in Alaska and northwest Canada through the end of the 21st century. By 2100, based on Representative Concentration Pathways (RCPs) 4.5–8.5 forcings, summer temperatures are predicted to increase between +2.1 and +4.6°C, while solid precipitation (snow) is predicted to decrease by –6 to –11%, despite a +9 to +21% increase in total precipitation. Snow is predicted to undergo a pronounced decrease in the fall, shifting the start of the accumulation season back by ~1 month. In response to these forcings, the regional equilibrium line altitude (ELA) may increase by +105 to +225 m by 2100. The mass balance sensitivity to this increase is highly variable, with the most substantive impact for glaciers with either limited elevation ranges (often small (<1 km2) glaciers, which account for 80% of glaciers in the region) or those with top-heavy geometries, like icefields. For more than 20% of glaciers, future ELAs, given RCP 6.0 forcings, will exceed the maximum elevation of the glacier, resulting in their eventual demise, while for others, accumulation area ratios will decrease by >60%. Our results highlight the first-order control of hypsometry on individual glacier response to climate change, and the variability that hypsometry introduces to a regional response to a coherent climate perturbation.

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In The News

Scientists seek U.S. backcountry skiers to measure snowpack

The Washington Post, Dan Joling

NASA’s earth science arm is funding research that recruits citizen scientists on skis, snowshoes and snowmobiles to measure snow depth in backcountry locations of the Pacific Northwest and Alaska. The snowpack measurements are incorporated into computer models estimating "snow-water equivalent," the amount of liquid water contained in snow cover, of a watershed.

5 Jan 2018

Mountain glaciers shrinking across the West

UW News, Hannah Hickey

In 2012, David Shean first asked for satellite time to turn digital eyes on glaciers in the continental U.S., and he has since collected enough data to analyze mass loss for Mount Rainier and almost all the glaciers in the lower 48 states.

20 Oct 2017

NASA High Mountain Asia Project

eScience Institute

Over one billion people live downstream of the region referred to as High Mountain Asia, an area ranging from the Hindu Kush and Tien Shan in the west to the Eastern Himalaya, and home to “the world’s largest reservoir of perennial glaciers and snow outside of the Earth’s polar ice sheets”. The High Mountain Asia (HMA) Project, led by Anthony Arendt, eScience senior data science fellow and senior research scientist with the UW Polar Science Center at the Applied Physics Laboratory, aims to “generate knowledge on how climate change is impacting the water resources of that region.”

25 Jul 2017

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