Characterizing the cryosphere

This special issue of Physical Geography features selected papers on topics of snow and snow hydrology primarily drawn from studies presented at the Eastern Snow Conference (ESC). The ESC is a joint American and Canadian forum for discussing recent work on operational, applied, and scientific issues related to snow and ice. The ESC (http://www.easternsnow.org/) has published its annual conference proceedings Since 1952. This special issue serves as an important outlet for research activity in the physical geography of snow and ice and showcases key ongoing and emerging thematic areas in this dynamic component of the climate system, which impacts runoff, weather conditions and ecosystems. The importance of snow in the Earth system is illustrated by the significant response of glaciers, snowpack characteristics, and snow cover extent to climate change, noted at the ESC annual meeting. Globally, the cumulative mass balance of alpine glaciers from 1980 to 2015 was –18.8 m (Pelto, 2016). The trend of diminishing mass balance has been remarkably consistent from region to region (WGMS, 2015). The rate at which glaciers have lost mass has increased in recent decades. The decadal mean annual mass balance was –. 26 m in the 1980s, –. 39 m in the 1990s, –. 73 m in the 2000s, and –. 82 m from the half decade of 2010–2015. The declining mass balance trend during a period of glacial retreat indicates alpine glaciers are not approaching equilibrium and widespread retreat will continue (Zemp et al., 2015). Monthly SCE is calculated at the Rutgers Global Snow Lab from daily SCE maps produced by meteorologists at the National Ice Center based primarily on visible satellite imagery. From 1967 to 2015, mean Northern Hemisphere spring SCE declined 10% (Robinson, Estilow, & NOAA CDR Program, 2012). For the Northern Hemisphere, this trend signifies substantial changes in snow covered extent (SCE) that will impact hydrology, weather, and ecosystems. Of the six papers in this issue, five examine the efficacy of modeled snow and ice products derived from satellite imagery. Sugg, with co-authors Fuhrmann, Perry, Hall, and Konrad, analyzed 63 snow events in the Southern Appalachian Mountains using Moderate-resolution Imaging Spectroradiometer standard snow cover products to ascertain qualitative and quantitative differences in snow cover across the region. Among subregions, they found significant variation in the snow cover pattern from individual synoptic classes. Côté, Madore, and Langlois employed the SNOWPACK model driven with both in-situ and forecasted meteorological data in three different Canadian climate and geomorphological contexts for the purpose of avalanche forecasting. Their meteorological data comparison from in-situ and predicted datasets for two winters showed that the GEMLAM weather model is the most accurate for the three climatic contexts, with snow simulations forced with GEMLAM being closest to field measurements. This allowed predictions of persistent weak layers that have been validated using the InfoEx platform from Avalanche Canada. Ouellet and colleagues employed a spatially explicit assessment tool using snow model simulations to characterize snow conditions for Peary caribou grazing in the Canadian Arctic. Their analysis concluded that caribou counts are affected by simulated snow density values >300 kg m−3, particularly where cumulative seasonal snowpack thicknesses >7000 cm occur. Busseau, Royer, Roy, Langlois, and Domine conducted a field study at the Umiujaq site, Nunavik, which is