Variability of accumulation in northwest Greenland over the past 250 years

Abstract

During summer 1996, a 120‐m firn and ice core was drilled to determine annual accumulation rates at a northwest Greenland site (GITS, 77.1392°N, 61.0422°W, 1910 m elevation). Annual layers were identified in the core using multiple parameters: δ18O and concentrations of dust, hydrogen peroxide, ammonium, calcium and nitrate. Using all parameters together to define annual layers resulted in a 251‐year record with a dating uncertainty of one year within that period. Annual accumulation over the period of record averaged about 0.37 m water equivalent. Comparing this record with four other multi‐century long records from the west central and northwest portion of the ice sheet shows many periods when decadal‐scale fluctuations in accumulation at the different sites are in phase. Overall variations in accumulation in this portion of the ice sheet were ±8–9% per decade, versus ±25% for individual cores. Annual accumulation at GITS showed a significant correlation with a 12‐month North Atlantic Oscillation index (Pearson's R=−0.32 with a significance level of >99%), though the correlation was slightly lower than for two cores roughly 350 and 700 km south.