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Anthony Arendt

Research Scientist/Engineer - Principal

Email

arendta@apl.washington.edu

Phone

206-685-4551

Department Affiliation

Polar Science Center

Education

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

Publications

2000-present and while at APL-UW

Assessing controls on mass budget and surface velocity variations of glaciers in Western Himalaya

Bhushan, S., T.H. Syed, A.A. Arendt, A.V. Kulkarni, and D. Sinha, "Assessing controls on mass budget and surface velocity variations of glaciers in Western Himalaya," Sci. Rep., 8, 8885, doi:10.1038/s41598-018-27014-y, 2018.

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11 Jun 2018

This study analyses spatially resolved estimates of mass budget and surface velocity of glaciers in the Zanskar Basin of Western Himalaya in the context of varying debris cover, glacier hypsometry and orientation. The regional glacier mass budget for the period of 1999–2014 is –0.38 ± 0.09 m w.e./a. Individual mass budgets of 10 major glaciers in the study area varied between –0.13 ± 0.07 and –0.66 ± 0.09 m w.e./a. Elevation changes on debris-covered ice are considerably less negative than over clean ice. At the same time, glaciers having >20% of their area covered by debris have more negative glacier-wide mass budgets than those with <20% debris cover. This paradox is likely explained by the comparatively larger ablation area of extensively debris-covered glaciers compared to clean-ice glaciers, as indicated by hypsometric analysis. Additionally, surface velocities computed for the 2013–14 period reveal near stagnant debris-covered snouts but dynamically active main trunks, with maximum recorded velocity of individual glaciers ranging between ~50 ± 5.58 and ~90 ± 5.58 m/a. The stagnant debris-covered extent, which varies from glacier-to-glacier, are also characterized by ice cliffs and melt ponds that appreciably increase the overall surface melting of debris-covered areas.

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.

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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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