Reanalysis of the US Geological Survey Benchmark Glaciers: long-term insight into climate forcing of glacier mass balance

O’Neel, S.; McNeil, Christopher J.; Sass, Louis C.; Florentine, Caitlyn; Baker, Emily H.; Peitzsch, Erich H.; McGrath, Daniel; Fountain, Andrew G.; Fagre, Daniel B.

doi:10.1017/jog.2019.66

Cited by 63 publications

(101 citation statements)

References 93 publications

(152 reference statements)

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“…Their results are similar to our results for 1986–2005 for the same ice masses (area loss of 91 ± 22 km 2 , 4.2%). O'Neel and others (2019) found that the Wolverine glacier experienced a 1.5 km 2 area reduction between 1969 and 2018, which is similar to the area loss of 1.4 km 2 found in this study for the period 1986–2016.…”

Section: Resultssupporting

confidence: 87%

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Glacier mass and area changes on the Kenai Peninsula, Alaska, 1986–2016

et al. 2020

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Glacier mass loss in Alaska has implications for global sea level rise, fresh water input into the Gulf of Alaska and terrestrial fresh water resources. We map all glaciers (>4000 km2) on the Kenai Peninsula, south central Alaska, for the years 1986, 1995, 2005 and 2016, using satellite images. Changes in surface elevation and volume are determined by differencing a digital elevation model (DEM) derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer stereo images in 2005 from the Interferometric Synthetic Aperture Radar DEM of 2014. The glacier area shrunk by 543 ± 123 km2 (12 ± 3%) between 1986 and 2016. The region-wide mass-balance rate between 2005 and 2014 was −0.94 ± 0.12 m w.e. a−1 (−3.84 ± 0.50 Gt a−1), which is almost twice as negative than found for earlier periods in previous studies indicating an acceleration in glacier mass loss in this region. Area-averaged mass changes were most negative for lake-terminating glaciers (−1.37 ± 0.13 m w.e. a−1), followed by land-terminating glaciers (−1.02 ± 0.13 m w.e. a−1) and tidewater glaciers (−0.45 ± 0.14 m w.e. a−1). Unambiguous attribution of the observed acceleration in mass loss over the last decades is hampered by the scarcity of observational data, especially at high elevation, and by large interannual variability.

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Section: Resultssupporting

confidence: 87%

“…Also, all five benchmark glaciers in Alaska (Gulkana, Wolverine, Lemon Creek, South Cascade and Sperry Glacier) have lost mass with average mass-balance rates ranging from −0.58 to −0.30 m w.e. a −1 since mid-20 th century (O'Neel and others, 2014; O'Neel and others, 2019).…”

Section: Introductionmentioning

confidence: 99%

Glacier mass and area changes on the Kenai Peninsula, Alaska, 1986–2016

et al. 2020

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“…We assessed geodetic mass balance uncertainty from DEM accuracy and alignment, data gaps and density assumptions using methods identical to the USGS Benchmark Glacier Project (O'Neel and others, 2019). Errors from accuracy and alignment were quantified with the normalized median absolute deviation (NMAD) of post co-registration residual differences over stable, snow-free bedrock, between a given DEM and the reference DEM (Shean and others, 2016).…”

Section: Methodsmentioning

confidence: 99%

“…We used a mass balance model (Van Beusekom and others, 2010; O'Neel and others, 2019) to adjust mid-season measurements to a consistent time system. A positive degree-day (PDD) model (e.g.…”

Section: Methodsmentioning

confidence: 99%

Explaining mass balance and retreat dichotomies at Taku and Lemon Creek Glaciers, Alaska

et al. 2020

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We reanalyzed mass balance records at Taku and Lemon Creek Glaciers to better understand the relative roles of hypsometry, local climate and dynamics as mass balance drivers. Over the 1946–2018 period, the cumulative mass balances diverged. Tidewater Taku Glacier advanced and gained mass at an average rate of +0.25 ± 0.28 m w.e. a–1, contrasting with retreat and mass loss of −0.60 ± 0.15 m w.e. a−1 at land-terminating Lemon Creek Glacier. The uniform influence of regional climate is demonstrated by strong correlations among annual mass balance and climate data. Regional warming trends forced similar statistically significant decreases in surface mass balance after 1989: −0.83 m w.e. a–1 at Taku Glacier and −0.81 m w.e. a–1 at Lemon Creek Glacier. Divergence in cumulative mass balance arises from differences in glacier hypsometry and local climate. Since 2013 negative mass balance and glacier-wide thinning prevailed at Taku Glacier. These changes initiated terminus retreat, which could increase dramatically if calving begins. The future mass balance trajectory of Taku Glacier hinges on dynamics, likely ending the historic dichotomy between these glaciers.

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“…South Cascade Glacier is a small mountain glacier that has an extensive history of scientific study (e.g. Krimmel, 1989; Fountain, 1994), in part due to its status as a USGS benchmark glacier (Meier, 1961; O'Neel and others, 2019). Seasonal mass-balance surveys have been performed here every spring and fall since 1959.…”

Section: Methodsmentioning

confidence: 99%

ImpDAR: an open-source impulse radar processor

et al. 2020

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Despite widespread use of radio-echo sounding (RES) in glaciology and broad distribution of processed radar products, the glaciological community has no standard software for processing impulse RES data. Dependable, fast and collection-system/platform-independent processing flows could facilitate comparison between datasets and allow full utilization of large impulse RES data archives and new data. Here, we present ImpDAR, an open-source, cross-platform, impulse radar processor and interpreter, written primarily in Python. The utility of this software lies in its collection of established tools into a single, open-source framework. ImpDAR aims to provide a versatile standard that is accessible to radar-processing novices and useful to specialists. It can read data from common commercial ground-penetrating radars (GPRs) and some custom-built RES systems. It performs all the standard processing steps, including bandpass and horizontal filtering, time correction for antenna spacing, geolocation and migration. After processing data, ImpDAR's interpreter includes several plotting functions, digitization of reflecting horizons, calculation of reflector strength and export of interpreted layers. We demonstrate these capabilities on two datasets: deep (~3000 m depth) data collected with a custom (3 MHz) system in northeast Greenland and shallow (<100 m depth, 500 MHz) data collected with a commercial GPR on South Cascade Glacier in Washington.

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Reanalysis of the US Geological Survey Benchmark Glaciers: long-term insight into climate forcing of glacier mass balance

Cited by 63 publications

References 93 publications

Glacier mass and area changes on the Kenai Peninsula, Alaska, 1986–2016

Glacier mass and area changes on the Kenai Peninsula, Alaska, 1986–2016

Explaining mass balance and retreat dichotomies at Taku and Lemon Creek Glaciers, Alaska

ImpDAR: an open-source impulse radar processor

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