506. Jimenez et al. (2024) Volume loss and surface deflation at Emmons Glacier, Mount Rainier, WA
     Emmons Glacier is a debris-covered glacier which is situated on the northeastern side of Mount Rainier, WA. The glacier surface is bare ice or surface snow at higher elevations but is debris-covered in the lower elevation ablation zone. Thick debris-cover on glaciers has been known to reduce ice melt but current climate conditions along with a thin debris-cover have led to increased surface melting. Understanding how debris cover influences glacier melt is important for understanding how Mount Rainier glaciers will continue to evolve. This study addresses whether significant elevation change in the lower ablation area of Emmons Glacier corresponds with significant changes in debris-cover morphology; we expect that elevation change is linked to variations in debris cover. We import high-resolution Digital Elevation Models (DEMs) surveyed by the National Park Service in 2021 and a Light Detection and Ranging (LiDAR) topographic survey collected in October 2007/2008 into ArcGIS Pro to investigate glacier change. We can use these data to calculate changes in surface elevation and glacier volume using spatial analysis tools such as DEM differencing, Surface Volume, Geomorphon Landforms, and geostatistical interpolation. To complete DEM differencing, we subtract the 2007/8 surface from the 2021 surface to obtain a difference map which shows us areas where the glacier surface has thickened and thinned. We use the difference map to calculate the volume loss between the surface and a flat reference plane set at zero elevation. Geomorphon analysis classifies landforms elements into 10 common types such as peaks, ridges, valleys, and spurs, using elevation difference analysis around specific points. Applying this analysis to DEMs from 2007/2008 and 2021 shows geomorphological changes over the 13-year period. We also use geostatistical interpolation which estimates thickness of debris cover by analyzing spatial patterns and predictions of our in-situ surface rock debris to glacier ice depth data. Our preliminary results suggest that volume loss and surface deflation correspond with areas of thin debris and geomorphic change. DEM differencing indicates a consistent pattern of ice loss in the lower ablation zone. Geomorphic changes over the last 13 years show significant shifts in debris cover and glacier morphology.
553. Nuth and Kaab (2011) Co-registration and bias corrections of satellite elevation data sets for quantifying glacier thickness change
     There are an increasing number of digital elevation models (DEMs) available worldwide for deriving elevation differences over time, including vertical changes on glaciers. Most of these DEMs are heavily post-processed or merged, so that physical error modelling becomes difficult and statistical error modelling is required instead. We propose a three-step methodological framework for assessing and correcting DEMs to quantify glacier elevation changes: (i) remove DEM shifts, (ii) check for elevation-dependent biases, and (iii) check for higher-order, sensor-specific biases. A simple, analytic and robust method to co-register elevation data is presented in regions where stable terrain is either plentiful (case study New Zealand) or limited (case study Svalbard). The method is demonstrated using the three global elevation data sets available to date, SRTM, ICESat and the ASTER GDEM, and with automatically generated DEMs from satellite stereo instruments of ASTER and SPOT5-HRS. After 3-D co-registration, significant biases related to elevation were found in some of the stereoscopic DEMs. Biases related to the satellite acquisition geometry (along/cross track) were detected at two frequencies in the automatically generated ASTER DEMs. The higher frequency bias seems to be related to satellite jitter, most apparent in the back-looking pass of the satellite. The origins of the more significant lower frequency bias is uncertain. ICESat-derived elevations are found to be the most consistent globally available elevation data set available so far. Before performing regional-scale glacier elevation change studies or mosaicking DEMs from multiple individual tiles (e.g. ASTER GDEM), we recommend to co-register all elevation data to ICESat as a global vertical reference system.
552. Hotaling et al. (2022) Summer dynamics of microbial diversity on a mountain glacier
     Glaciers are rapidly receding under climate change. A melting cryosphere will dramatically alter global sea levels, carbon cycling, and water resource availability. Glaciers host rich biotic communities that are dominated by microbial diversity, and this biodiversity can impact surface albedo, thereby driving a feedback loop between biodiversity and cryosphere melt. However, the microbial diversity of glacier ecosystems remains largely unknown outside of major ice sheets, particularly from a temporal perspective. Here, we characterized temporal dynamics of bacteria, eukaryotes, and algae on the Paradise Glacier, Mount Rainier, USA, over nine time points spanning the summer melt season. During our study, the glacier surface steadily darkened as seasonal snow melted and darkening agents accumulated until new snow fell in late September. From a community-wide perspective, the bacterial community remained generally constant while eukaryotes and algae exhibited temporal progression and community turnover. Patterns of individual taxonomic groups, however, were highly stochastic. We found little support for our a priori prediction that autotroph abundance would peak before heterotrophs. Notably, two different trends in snow algae emerged—an abundant early- and late-season operational taxonomic unit (OTU) with a different midsummer OTU that peaked in August. Overall, our results highlight the need for temporal sampling to clarify microbial diversity on glaciers and that caution should be exercised when interpreting results from single or few time points.
551. Kincaid (2024) Using historic glacial data and GIS to predict Mount Rainier National Park's glacial future
     Will Washington state have glaciers 100 years from now (year 2124)? Due to generally warmer weather glaciers are largely in retreat globally, including the glaciers in Washington state. In Washington state summer glacial meltwater plays a vital role in the survival of wildlife and is needed for human purposes that include recreation, power generation, drinking, agricultural, and industrial. This project looked at the most resilient glaciers in Washington state, the glaciers at Mount Rainier National Park. Historic measurements were used in an exponential growth calculation to project the amount in acres each glacier at Mount Rainer will advance or retreat over the next 100 years. The glaciers were digitized into ArcGIS Pro and then adjusted according to the calculations. The results of the project show that all the glaciers at Mount Rainier should be intact in 2124. This is of vital importance to wildlife and human populations that depend on the summer meltwater for various purposes.
550. Florea et al. (2022) Fumarole-ice dynamics in cryo-speleology on volcanic edifices—Mount Rainier, Washington, USA
     The persistent fumarole ice caves nearly circumnavigating the East Crater of Mount Rainier in the Cascade Volcanic Arc in Washington, USA, are a natural laboratory to study the dynamic equilibrium between thermal flux and glacial ice. The large circum‐crater passage connects to entrances on the crater rim by steep transverse passages, and fumarole gas convection and advection maintains the cave passage distribution and morphology. Between August 2016 and August 2017, we collected hourly data using remote sondes that include temperatures at three fumarole, cave air temperature and pressure, water temperature and depth in an in‐cave meltwater lake, and the outside temperature and snow depth at Paradise Visitors Center. Correlation and wavelet analyses of these data reveal complex associations between patterns of weather, fumarole activity, and lake level. At longer scales, fumarole temperatures behave largely independently and connected to spatial and temporal changes in volcanic heat flux and glacial melt circulation. At the scale of individual storm‐events, major snowfalls seal the cave entrances, increasing cave air temperature and pressure from fumarole output and causing rising lake levels from increased melt until entrances reopen. Repeating freeze‐thaw cycles observed in the cave monitoring data are a primary cause of crater mass‐wasting.
549. Stenner et al. (2023) Morphodynamics of glaciovolcanic caves—Mount Rainier, Washington, USA
     The twin summit craters of Mount Rainier, Washington, USA host the largest known glaciovolcanic caves in the world and at 4382 m, the highest elevation caves in the USA. The caves are formed in ice at the glacier-rock interface by volcanogenic gases and atmospheric advection. However, the way in which discrete caves are formed and evolve remains poorly understood. Surveys of the cave systems in 1970−1973 and 1997−1998 in both the West and East Craters documented cave passage morphology. Field expeditions from 2014−2017 comprehensively surveyed the Rainier summit caves and undertook thermal imaging and temperature monitoring. Significant changes had occurred. In the East Crater, documented cave length has nearly doubled since 1973 to 3593 m of passage spanning 144 m of depth, revealing a new subglacial lake, and now nearly circumnavigating the East Crater. Of the reported increase in length, some 600 m of the mapped passage is possibly newly formed. Across 47 years of observation, certain sections of the cave appear to be preserved in form and position through time, while others are more actively being lost or forming. Conserved passages are generally sub-horizontal, passages following the curvilinear crater contours, show low temperature variability, and are dependent on perennial fumarolic activity or distributed heat flux emanating from warm bedrock and sediment floors. Transient passages are smaller diameter dendritic passages following the slope of the ice-rock interface towards entrance zones and normal to the circum-crater passage. They also show higher variability in temperature and airflow and are subject to seasonal weather and mechanical collapse, which may contribute to transience. Additional research is required to confirm the mechanisms maintaining conserved passages and formation of transient passages.

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The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington Pacific Northwest Seismic Network continue to monitor Washington and Oregon volcanoes closely and will issue additional notifications as warranted.

Website Resources

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cvo
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/programs/VHP/volcano-notifications-deliver-situational-information

Jon Major, Scientist-in-Charge, Cascades Volcano Observatory, jjmajor@usgs.gov

General inquiries: vhpweb@usgs.gov