Mar 7, 2019

Increased Greenland melt triggered by large-scale, year-round cyclonic moisture intrusions

Oltmanns, Marilena, Straneo, Fiammetta, Tedesco, Marco
The Cryosphere
  • States that surface melting is a major driver of Greenland's mass loss
  • Focuses on the triggers of melt by examining the synoptic atmospheric conditions associated with 313 rapid melt increases, detected in a satellite-derived melt extent product, equally distributed throughout the year over the period 1979–2012
  • Combines reanalysis and weather station data and shows that melt is initiated by a cyclone-driven, southerly flow of warm, moist air, which gives rise to large-scale precipitation
  • A decomposition of the synoptic atmospheric variability over Greenland suggests that the identified, melt-triggering weather pattern accounts for ∼40 % of the net precipitation, but increases in the frequency, duration and areal extent of the initiated melting have shifted the line between mass gain and mass loss as more melt and rainwater run off or accumulate in the snowpack
  • Estimates that the initiated melting more than doubled over the investigated period, amounting to ∼28 % of the overall surface melt and revealing that, despite the involved mass gain, year-round precipitation events are participating in the ice sheet's decline