2017 Ablation Zone Photos
In July 2017 I spent 1 week at a field location in the ablation zone in the Issunguata Sermia catchment. This field site was where scientists from the University of Montana and University of Wyoming installed inclinometers and temperature sensors throughout the ice column in 9 boreholes. I helped to dismantle the field experiments and map the bed using ground penetrating radar.
2017 Ablation Zone Photos
In July 2017 I spent 1 week at a field location in the ablation zone in the Issunguata Sermia catchment. This field site was where scientists from the University of Montana and University of Wyoming installed inclinometers and temperature sensors throughout the ice column in 9 boreholes. I helped to dismantle the field experiments and map the bed using ground penetrating radar.
2017 Ablation Zone Photos
PhD Research: Local Weather Conditions Create Structural Differences between Shallow Firn Columns at Summit, Greenland and WAIS Divide, Antarctica
Firn density profiles (a,b) and permeability profiles (c,d) between 3.5 m and 11 m depth at GIS Summit (a,c) and WAIS Divide (b,d). The solid black line in panels (a,b) is the modeled firn density profile generated from Herron and Langway (1980) [12]. In panels (c,d), the solid black line represents the modeled permeability profile from Adolph and Albert (2014) [14] and the dashed black line shows modeled permeability profiles using the model of Freitag et al. (2002) [15]. All modeled density and permeability profiles shown were generated using an accumulation rate of 0.22 m yr−1, mean air temperature of −28 °C, and surface snow density of 0.34 g cm−3.
Understanding how physical characteristics of polar firn vary with depth assists in interpreting paleoclimate records and predicting meltwater infiltration and storage in the firn column. Spatial heterogeneities in firn structure arise from variable surface climate conditions that create differences in firn grain growth and packing arrangements. Commonly, estimates of how these properties change with depth are made by modeling profiles using long-term estimates of air temperature and accumulation rate. Here, we compare surface meteorology and firn density and permeability in the depth range of 3.5–11 m of the firn column from cores collected at Summit, Greenland and WAIS Divide, Antarctica, two sites with the same average accumulation rate and mean annual air temperature.
We show that firn at WAIS Divide is consistently denser than firn at Summit. However, the difference in bulk permeability of the two profiles is less statistically significant. We argue that differences in local weather conditions, such as mean summer temperatures, daily temperature variations, and yearly wind speeds, create the density discrepancies. Our results are consistent with previous results showing density is not a good indicator of firn permeability within the shallow firn column. Future modeling efforts should account for these weather variables when estimating firn structure with depth.
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Read the full published manuscript in Atmosphere here.
Meteorological data from both Summit (panels (a,c,e)) and WAIS Divide (panels (b,d,f). Air temperatures at the two sites are shown in panels (a,b), relative humidity values are displayed in panels (c,d), and wind speeds are plotted in panels (e,f). Hourly data are plotted from the years 1997–2007 for Summit and 2009–2019 for WAIS Divide vs. the day of the collection year with grey transparent lines, so that progressively darker greys show overlapping data. Black lines show a mean meteorological value for the given day of the year, averaged over the collection period.