Faceted crystal formation in the northeast Greenland low-accumulation region

Snow-pit analysis in the low-accumulation region in northeast Greenland ind icated a mean annual accumulation of 12 +/- 1.6 cm. It also revealed numero us faceted layers that were not related to the summer horizon of previous y ears. In general, the faceted crystals were found under a wind crust. These crusts appear to originate during the winter. Snow- and air-temperature da ta from automatic weather stations suggest that the katabatic storms are re sponsible for the formation of the wind crusts and the faceted layers. Freq uent, abrupt temperature changes up to 30 degrees C were observed within tw o days, due to turbulent mixing of cold-air inversions. The near-surface ai r-temperature variations are correlated with wind speed, the latter leading the former by 6-9 hours for increasing wind, and 1-4 hours for decreasing wind. Because of low accumulation, katabatic storms affect the same snow su rface for several months, causing repeated air-temperature fluctuations. Th is leads to strong vapor-pressure gradients and faceted crystal growth in t he top snow layer On average we found two faceted layers (in addition to th e summer layer) per year for a 1 year record. In addition to its climatolog ical significance in the snow record, the formation of these layers is espe cially important to understand for the interpretation of microwave satellit e observations of the firn.