Recent Snow Accumulation Variability in Northwest Greenland from a Compilation of Snow Pits, Ice Cores, and Instrumental Records

Abstract:

Accumulation (precipitation minus evaporation or sublimation) is fundamental to understanding the mass balance of the Greenland Ice Sheet (GIS). Increases in accumulation rates over an ice sheet may be driven by the higher saturation vapor pressure with rising temperatures (e.g., Davis et al., 2005), and/or changes in atmospheric circulation patterns such as the North Atlantic Oscillation (NAO) (Appenzeller et al., 1998; Mosley-Thompson et al., 2005). Ground-penetrating radar data taken along the 2011 Greenland Inland Traverse indicate that northwest Greenland accumulation rates have increased approximately ~10% in the dry-snow zone over the past 50 years (Hawley et al., 2014), with differences in accumulation values more pronounced in the lower-elevation, coastal region near Thule. A similar pattern is also observed in snow pit data collected along the traverse when compared to traverse snowpit data from the 1950s. Accumulation rates derived from northwest Greenland shallow cores, however, indicate no statistically significant trend in annual accumulation (Bales et al., 2001; Buchardt et al., 2012). Here we present a compilation of precipitation (accumulation) instrumental and proxy records from the northwest GIS in an effort to reconcile these observations and improve our understanding of NW Greenland accumulation variability over the past ~100 years. Our analysis incorporates records from snowpits, shallow cores, and historical datasets including precipitation data from coastal meteorological stations (Cappelen et al., 2011). We assess the sensitivity of snow accumulation to factors including topography, temperature variability, and changes in atmospheric circulation. Preliminary analyses support the hypothesis that accumulation has been rising in coastal regions of the ice sheet for the past two decades without a significant trend further inland.