Fattore AAR (Acculumation Area Ratio), variazioni frontali e ralazioni con il clima sui ghiacciai delle Alpi Lombarde

AAR Factor, snout variations and climatic fluctuations on the glaciers in the Alps of Lombardy (Italy)

Abstract

The AAR factor (Accumulation Area Ratio) represents a good synthetic glacier balance indicator. The AAR factors for a sample of glaciers in the Lombard Alps are compared. This sample was selected from the World Glacier Inventory (unpublished data referring from 1981-82) and from the Catasto dei Ghiacciai Lombardi, published in 1992 by the Servizio Glaciologico Lombardo. The AAR changed from a mean of 0,62 to 0,27, and therefore, from a small positive or zero balance to a negative balance. We think that the two situations are indicative of the evolution of glaciation in Lombardy over recent decades. As is demonstrated through the examination of the snout variations of several glaciers, this period saw a phase of expansion that culminated in the latter part of the 1970's, followed by a recession phase that is still on-going. The analysis of the data from the Sondrio and S. Caterina Valfurva stations has afforded the identification of a cold phase, after a warm and wet period up until the beginning of the 1950's, which continued until the mid 1980's, when there was another rise in temperatures.