On the mass balance of low latitude glaciers with particular considerationof the Peruvian Cordillera Blanca

Glacier mass balance studies in the low latitudes are rare and glaciologica l methods and terminology are basically adapted from mid- and high latitude conditions. The low latitudes are considered to be the tropics and, to som e extent, the adjoining dry subtropics. The outer tropics are proposed as a n intermediate zone with tropical character during the humid season and sub tropical character during the dry season. Delimitations as well as respecti ve climate and glacier regimes are discussed in order to distinguish them f rom each other and from the mid-latitudes. Different sensitivities of the g laciers can be expected and promise, in turn, a complex climatological inte rpretation of glacier fluctuations. For this, detailed mass balance studies on low latitude glaciers are required. The respective discussion is concen trated on the Peruvian Cordillera Blanca whose topographical setting provid es both spatial and temporal subdivisions in humid and dry regimes in one r egion. However, theoretical considerations and field experience show proble ms for the determination of mass balance variables in the Cordillera Blanca and the low latitudes in general. The absence of annual temperature variat ions hinders the development of impermeable layers which can be identified as annual reference layers and which prevent meltwater from percolating int o the firn body. Thus, a combination of ablation measurements and the appli cation of the flux divergence method for the determination of accumulation is proposed.