Past estimates of Greenland Ice Sheet accumulation rates have been multiyear climatologies based on ice/firn cores and coastal precipitation records. Existing annually resolved estimates have incompletely quantified uncertainty, owing primarily to incomplete spatial coverage. This study improves upon these shortcomings by calibrating annual (1958-2007) solid precipitation output from the Fifth Generation Mesoscale Model modified for polar climates (Polar MM5) using firn core and meteorological station data. The calibration employs spatial interpolation of regionally derived linear correction functions. Residual uncertainties exhibit coherent spatial patterns, which are modeled via spatial interpolation of root mean squared errors. Mean 1958-2007 Greenland Ice Sheet annual accumulation rate is 337 ± 48 mm/yr water equivalent (w.e.) or 591 ± 83 Gt/yr. Annual estimates contain one standard deviation uncertainties of 74 mm/yr w.e., 22%, or 129 Gt/yr. Accumulation rates in southeast Greenland are found to exceed 2000 mm/yr w.e. and to dominate interannual variability in Greenland Ice Sheet total accumulated mass, representing 31% of the whole. Accumulation rates in the southeast are of sufficient magnitude to affect the sign of Greenland mass balance during some years. The only statistically significant temporal change in total ice sheet accumulation in the 1958-2007 period occurred between 1960 and 1972, when a simultaneous accumulation increase and decrease occurred in west and east Greenland, respectively. No statistically significant uniform change in ice sheet-wide accumulation is evident after 1972. However, regional changes do occur, including an accumulation increase on the west coast post-1992. The high accumulation rates of 2002-2003 appear to be confined to the southeast. Copyright 2010 by the American Geophysical Union.

We present a reconstruction of the Greenland Ice Sheet surface mass balance (SMB) from 1870 to 2010, based on merged Twentieth Century Reanalysis (20CR) and European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological reanalyses, and we compare our new SMB series with global and regional climate and atmospheric circulation indices during this period. We demonstrate good agreement between SMB annual series constructed from 20CR and ECMWF reanalyses for the common period of overlap and show statistically significant agreement of long-term modeled snowfall with ice-core-based accumulation data. We analyze variations in SMB for the last 140 years and highlight the periods with significantly increased runoff and decreased SMB since 1870, which have both been enhanced in the period since 1990, as well as interannual variations in SMB linked to Greenland climate fluctuations. We show very good agreement of our SMB series variations with existing, independently derived SMB series (RACMO2) variations for the past few decades of overlap but also a significant disparity of up to ∼200 km³ yr^-1 in absolute SMB values due to poorly constrained modeled accumulation reflecting a lack of adequate validation data in southeast Greenland. There is no significant correlation between our SMB time series and a widely referenced time series of North Atlantic icebergs emanating from Greenland for the past century, which may reflect the complex nature of the relationship between SMB and ice dynamical changes. Finally, we discuss how our analysis sheds light on the sensitivity and response of the Greenland Ice Sheet to ongoing and future global climate change, and its contribution to global sea level rise. Copyright 2011 by the American Geophysical Union.