Northern Greenland 2008 Extreme Snowmelt and Record

Extreme snowmelt occurred during summer 2008 over the northern part of the Greenland ice sheet, according to the analysis of microwave data recorded by the Special Sensor Microwave Imager (SSM/I) onboard the F13 satellite of the U.S. Defense Meteorological Satellites Program (DMSP). New records of the number of melting days were also observed over large portions of the same areas.

 

Anomalies of the 2008 number of melting days (e.g., the difference between the 2008 number of melting days and the 1979–2007 average) are reported in Figure 1. In 2008, melting in northern Greenland lasted up to 18 days longer than previous maximum values and the melting index (e.g., the number of melting days times the area subject to melting) was three times greater than the 1979–2007 average, with 1.545•106 square kilometers x days. Also of noticeable value are 2008 anomalies observed along Greenland’s west coast, with melting over this area lasting  up to 5–10 days longer than the average.

Unlike 2007, snowmelt over the whole Greenland ice sheet in 2008 was not significant at high elevations  Melt extent in 2008 was, however, above the 1979–2007 average, with the 2008 updated melt extent trend,of approximately 16,000 square kilometers/year. 

 

Results obtained with SSM/I are consistent with the outputs of the regional climate model Modèle Atmosphérique Régional (MAR ). The 2008 MAR-modeled runoff is 88% higher than the 1979-2007 mean and close to the 2007 value. Low modeled snowfall (13 % below the 1979-2007 mean) and high runoff values suggest that the 2008 modeled surface mass balance (SMB =  SF – E – R where SF = snowfall, E = evaporation including surface water fluxes from a frozen surface (sublimation and deposition) and from a melting surface (evaporation and condensation) and R = run-off defined as the liquid water production (including melt and rainfall) minus the melt water retention)  could be negative for the second year in a row. Coherent with both SSM/I and MAR, SMB anomaly for 2008 derived from ground observations in southwestern Greenland was not outstanding, being 4 % above the long term mean. Unfortunately, no SMB measurements are available over those areas where new records were set. Nevertheless, the analysis of ground measurements carried out by automatic weather stations of the World Meteorological Organization indicates that 2008 surface/air maximum temperature, averaged for the period of June through August, were above the average (1979–2007) by up to 3º C, with new records set at several stations, including at stations located close to those areas where snowmelt record is observed.

 

Interestingly, the region where extreme snowmelt and maximum temperature positive anomalies in 2008 occurred witnessed other noticeable events during the summer of 2008, such as a wave of ice shelf disintegration along the northern Ellesmere coast  and the loss of 29 square kilometers of ice by  the Petermann Glacier‘s, along the northwestern coast of Greenland. Understanding how the different events are connected requires an interdisciplinary collaborative effort aimed at observing the Arctic as an integrated system.. In this sense, the consistency of satellite-, model-, and ground-based results poses the basis for a more robust analysis and synthesis tool.