Calibration and evaluation of a high-resolution surface mass-balance model for Paakitsoq, West Greenland

• Main Authors: Banwell, Alison F., Willis, Ian C., Arnold, Neil S., Messerli, Alexandra, Rye, Cameron J., Tedesco, Marco, Ahlstrøm, Andreas P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Glaciological Society 2012
• Subjects: Glacial lakes; Hydrology; Meltwater; Geomorphology; Mineralogy; Geology; Greenland; Ice Sheet
• Online Access: https://doi.org/10.7916/D8CF9Q01

Modelling the hydrology of the Greenland ice sheet, including the filling and drainage of supraglacial lakes, requires melt inputs generated at high spatial and temporal resolution. Here we apply a high spatial (100 m) and temporal (1 hour) mass-balance model to a 450 km2 subset of the Paakitsoq region, West Greenland. The model is calibrated by adjusting the values for parameters of fresh snow density, threshold temperature for solid/liquid precipitation and elevation-dependent precipitation gradient to minimize the error between modelled output and surface height and albedo measurements from three Greenland Climate Network stations for the mass-balance years 2000/01 and 2004/05. Bestfit parameter values are consistent between the two years at 400 kg m–3, 2° C and +14% (100 m)–1, respectively. Model performance is evaluated, first, by comparing modelled snow and ice distribution with that derived from Landsat-7 ETM+ satellite imagery using normalized-difference snow index classification and supervised image thresholding; and second, by comparing modelled albedo with that retrieved from the MODIS sensor MOD10A1 product. Calculation of mass-balance components indicates that 6% of surface meltwater and rainwater refreezes in the snowpack and does not become runoff, such that refreezing accounts for 31% of the net accumulation.