Autumn snowfall and hydroclimatic variability during the past millennium inferred from the varved sediments of meromictic Lake A, northern Ellesmere Island, Canada

摘要

We examined the hydroclimatic signal in a record of annual lamina (varve) thickness from High Arctic Lake A, Ellesmere Island (83°00.00'N, 75°30.00'W). In this unglacierized catchment, nival melt is the dominant source for meltwater and transport of sediment to the lake, and autumn snowfall is highly influential on varve thickness through the amount of snow available for melt in the following year. For the period during which climatic data are available, varve thickness in Lake A was significantly correlated (r= 0.50, p< 0.01) with the cumulative snowfall from August to October (ASO) during the previous year and, to a lesser extent, ASO mean daily temperature (r= 0.39, p< 0.01) at Alert, Nunavut (175. km east). The varve thickness record, interpreted as a proxy record of ASO snowfall and, by extension, ASO temperature, indicated above-mean conditions during five periods of the past millennium, including most of the 20th century. These results corresponded well to other available high-resolution proxy climate records from the region, with some discrepancies prior to AD 1500 and during the period AD 1700-1900.