Venticinque anni di bilancio di massa del Ghiacciaio del Caresèr (Alpi Cantrali), 1966-67/1990-91

Twenty-five years of mass balance of the Carèser Glacier (Central Alps), 1966-67/1990-91

Abstract

The Caresèr Glacier is located on the south-eastern slope of the Ortles-Cevedale Group and may be considered representative of the glaciated areas of the transitional belt between the continental-type Alpine climatic environment and that of the northern Mediterranean region. First examined by A. Desio in 1923, the behaviour of the glacier has been followed in detail until the present day. In particular from 1966 its mass balance has been thoroughly researched and it is still one of the sample basins of the IAHS-UNESCO World Glacier Monitoring Service. Surveys carried out using the glaciological surface method over a series of fixed-date balance years, give for the 1966-67/1990-91 period a value of -580 mm WE a^-1, corresponding to -2,8015 x 10⁶m³. However, in this time-span, two clearcut phases in glacier regime may be distinguished. From 196667 to 1979-80, mass balance was practically in equilibrium, with -130 mm WE a^-1; in the following period 1980-81/1990-91 it changed to -1080 mm WE a^-1. This behaviour is in agreement with the positive fluctuation of Alpine glaciers observed between 1965 and 1984, and with a new later phase of intensive retreat. The equilibrium line altitude (ELA), which at zero mass balance corresponds with the median elevation of the glacier (1967 survey) (3090 m; AAR = 509%), rose strongly during the 1980s (3371 m, as against a general average of 3210 m). The specific net balance is closely related (r = -0,93233) with the ELA, with a vertical gradient of 167,5 mm WE a^-1/ 50 m. According to computerized comparison of three aerial surveys, determination of the glacier’s variations in thickness and volume fully verify glaciological measurements for the entire period of study.