The influence of low-level thermal inversions on estimated melt-season characteristics in the central Canadian Arctic

摘要

Daily vertical temperature gradients were examined in order to infer melt-event characteristics at all elevation relevant to basin-scale snow and plateau ice-melt studies in the Canadian Arctic. Surface and Upper-air temperature data front Resolute, Cornwallis Island, was used to estimate vertical lapse rates up to 300 m asl, and to identify the presence of inversions at that altitude. Lapse rates vary throughout the melt season and are substantially less than typically published generalized values. Thermal inversions are more frequent during the melt season than ill the periods immediately before and after. suggesting a strong control on intraseasonal temperature patterns. In July, the period of maximum temperature ill the Arctic, inversion frequency is highest and closely related to calculated melting degree-days. Results show that increased summer mean temperature resulted in a substantial lengthening of estimated melt events, as opposed to increased event intensity. Increased inversion frequency leading to shallower vertical lapse rates since the late 1980s is speculated to be the result of synoptic-scale climate patterns, and is potentially an important meteorological mechanism for enhanced glacial melt since the late 1980s. Copyright (c) 2008 Royal Meteorological Society