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1. Sensitivity of glacier elevation analysis and numerical modeling to CryoSat-2 SIRAL retracking techniques

   https://doi.org/10.1016/j.cageo.2020.104610  

   Trantow, Thomas; Herzfeld, Ute C.; Helm, Veit; Nilsson, Johan (January 2021, Computers & Geosciences)

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2. Examining the variability of rock glacier meltwater in space and time in high-elevation environments of Utah, United States

   https://doi.org/10.3389/feart.2023.1129314  

   Munroe, Jeffrey S.; Handwerger, Alexander L. (April 2023, Frontiers in Earth Science)

   Rock glaciers are common geomorphic features in alpine landscapes and comprise a potentially significant but poorly quantified water resource. This project focused on three complementary questions germane to rock glacier hydrology: 1) Does the composition of rock glacier meltwater vary from year to year? 2) How dependent is the composition of rock glacier meltwater on lithology? And 3) How does the presence of rock glaciers in a catchment change stream water chemistry? To address these questions, we deployed automated samplers to collect water from late June through mid-October 2022 in two rock-glacierized mountain ranges in Utah, United States characterized by different lithologies. In the Uinta Mountains of northern Utah, where bedrock is predominantly quartzite, water was collected at springs discharging from two rock glaciers previously shown to release water in late summer sourced from internal ice. In the La Sal Mountains of southeastern Utah, where trachyte bedrock is widespread, water was collected at a rock glacier spring, along the main stream in a watershed containing multiple rock glaciers, and from a stream in a watershed where rock glaciers are absent. Precipitation was also collected, and data loggers for water temperature and electric conductivity were deployed. Water samples were analyzed for stable isotopes with cavity ring-down spectroscopy and hydrochemistry with ICP-MS. Our data show that water discharging from rock glaciers in the Uinta Mountains exhibits a shift from a snowmelt source to an internal ice source over the course of the melt season that is consistent from year to year. We also found that the chemistry of rock glacier water in the two study areas is notably different in ways that can be linked back to their contrasting bedrock types. Finally, in the La Sal Mountains, the properties of water along the main stream in a rock-glacierized basin resemble the properties of water discharging from rock glaciers, and strongly contrast with the water in a catchment lacking rock glaciers. Collectively these results underscore the role of rock glaciers as an agent influencing the hydrochemistry of water in high-elevation stream systems. 

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3. Basal conditions of Malaspina Glacier

   https://doi.org/10.7914/sn/3j_2021  

   Truffer, Martin; Larsen, Chris; Fahnestock, Mark (January 2021, International Federation of Digital Seismograph Networks)

   In this active seismic experiment we will collect AVO data at two glacier sites. One is located over a glacier bed high and the other one over a depression. The goals is to use Amplitude vs Offset methods to determine the nature of the subglacial material. A line of 24 geophones will be buried in snow to protect them from wind noise and the line will be accurately surveyed with GPS. A set of 100 shot holes will be drilled into the underlying ice to obtain a large range of offsets, so that amplitudes can be compared over large offset angles. If possible, the data will also be used to find the thickness of a subglacial till layer. The seismic experiment is part of a large geophysical and remote sensing observational program with the goal to provide input data for an ice flow model that will explore possible future scenarios for this large glacier that is very vulnerable to future climate change. In a second experiment we will do attempt to measure the extent of buried ice in the glacier foreland. For this experiment we propose to use 4.5 Hz geophones and we will use a hammer for the active source. This is part of the same NSF funded work. 

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4. The Reference Elevation Model of Antarctica

   https://doi.org/10.5194/tc-13-665-2019  

   Howat, Ian M.; Porter, Claire; Smith, Benjamin E.; Noh, Myoung-Jong; Morin, Paul (January 2019, The Cryosphere)

   Abstract. The Reference Elevation Model of Antarctica (REMA) is thefirst continental-scale digital elevation model (DEM) at a resolution ofless than 10 m. REMA is created from stereophotogrammetry with submeterresolution optical, commercial satellite imagery. The higher spatial andradiometric resolutions of this imagery enable high-quality surfaceextraction over the low-contrast ice sheet surface. The DEMs are registeredto satellite radar and laser altimetry and are mosaicked to provide acontinuous surface covering nearly 95 % the entire continent. The mosaicincludes an error estimate and a time stamp, enabling change measurement.Typical elevation errors are less than 1 m, as validated by thecomparison to airborne laser altimetry. REMA provides a powerful newresource for Antarctic science and provides a proof of concept forgenerating accurate high-resolution repeat topography at continentalscales. 

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5. Biophysical Drivers of Coastal Treeline Elevation

   https://doi.org/10.1029/2023JG007525  

   Molino, G D; Carr, J A; Ganju, N K; Kirwan, M L (December 2023, Journal of Geophysical Research: Biogeosciences)

   Abstract Sea level rise is leading to the rapid migration of marshes into coastal forests and other terrestrial ecosystems. Although complex biophysical interactions likely govern these ecosystem transitions, projections of sea level driven land conversion commonly rely on a simplified “threshold elevation” that represents the elevation of the marsh‐upland boundary based on tidal datums alone. To determine the influence of biophysical drivers on threshold elevations, and their implication for land conversion, we examined almost 100,000 high‐resolution marsh‐forest boundary elevation points, determined independently from tidal datums, alongside hydrologic, ecologic, and geomorphic data in the Chesapeake Bay, the largest estuary in the U.S. located along the mid‐Atlantic coast. We find five‐fold variations in threshold elevation across the entire estuary, driven not only by tidal range, but also salinity and slope. However, more than half of the variability is unexplained by these variables, which we attribute largely to uncaptured local factors including groundwater discharge, microtopography, and anthropogenic impacts. In the Chesapeake Bay, observed threshold elevations deviate from predicted elevations used to determine sea level driven land conversion by as much as the amount of projected regional sea level rise by 2050. These results suggest that local drivers strongly mediate coastal ecosystem transitions, and that predictions based on elevation and tidal datums alone may misrepresent future land conversion. 

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