Accumulation over the Greenland ice sheet from historical and recent records

Water accumulation, defined as precipitation minus evaporation, was estimated over all of Greenland as part of a program to understand changes in ice sheet mass and elevation. Over 360 historical and recent point accumulation estimates on the Greenland ice sheet were evaluated, and 276 estimates that were judged to be high quality were used to develop the accumulation map. The data set includes 99 points developed as part of four investigations of the past 5-15 years; these are judged to have the greatest accuracy. Using kriging, the average accumulation over Greenland is estimated to be ∼30 g cm^-2 yr^-1. For the interior part of the ice sheet above 1800 m elevation, where most of the data were acquired, the average accumulation is also estimated to be ∼30 g cm^-2 yr^-1. There are still many areas on the ice sheet, including northwest, southeast, and southern Greenland, where accumulation is highly uncertain, exceeding the mean ice sheet uncertainty at a point of ∼20-25%. In these regions, further sampling will be required to reduce uncertainty in both regional and ice-sheet-wide accumulation.