During summer 1995, 150-m firm and ice cores were drilled to determine annual accumulation rates at two Greenland sites, 73.84 ¿N, 49.49 ¿W (NASA-U site) and 78.53 ¿N, 56.83 ¿W (Humboldt glacier site). Annual layers were identified in the cores using multiple parameters: Δ18O and concentrations of dust, H2O2, NH4+, Ca2+, and NO3-. Using all parameters together to define annual layers resulted in a 350-year record for the NASA-U core with no dating uncertainty. For the lower-accumulation Humboldt core, the dating uncertainty is about 5 years over the 852-year period of record, with no uncertainty over the past 200 years. Annual accumulation over the periods of record at the two sites averaged about 0.34 and 0.14 m water equivalent, respectively. A set of 20-m firn cores drilled near the main 150-m cores showed that interannual variability of accumulation exceeded spatial variability at NASA-U. The Humboldt cores showed equal spatial and interannual variability. The accumulation rates at both sites showed a low-frequency variation of about 100 years, and both sites showed 200-year cumulative fluctuations of about 2 m from mean accumulation rates. Compared to central Greenland and to NASA-U, the Humboldt core showed higher annual accumulation rates around 1760-1810, possibly indicating a changed circulation pattern for the more northern part of Greenland in that period. ¿ 1998 American Geophysical Union