Abstract:
The andean mountain complex of Chile presents a vast and heterogeneous succession of cryospheric systems, spanning a unique variety of climates in the world. Despite concentrating ~80% of the glaciarized area of the Andes, so far, in the country there is only one record of glacier mass balance over 30 years.The mountain glacier Echaurren Norte (33°35ʹS –70°08ʹW),a small extension (0.226 km2in 2008)of fragmented patches of debris-covered and both clean ice in the semi-arid Andes near Santiago de Chile,contains the most extensive and complete direct surface mass balance (SMB) measurements in the southern hemisphere.In this thesis,the evolution of the surface mass balance (SMB)of the Echaurren Norte glacier during the last 34 years of measurementis presented. Through a semi-empirical model of distributed mass balance with daily time steps,the annual SMB of the glacier are determined between the years 1979 to 2013. Furthermore, the climatic statical analysis(air temperature and precipitations)of the automatic weather stationEmbalse El Yeso (METyeso; 2475 m asl)between 1979 and 2014,is presented.The mean annual air temperature (MAT)inMETyesowas+8.78°C (σ= 0.69°C)between 1979-2014,while the mean annual precipitation (MAP) reached 637.7 mm (σ= 342.9mm)in the same time.In the model, the average SMBof the glacier showed a value-0.48 m w.eq. yr-1(meters water equivalent per year)during the study period,while the average SMB measured reaches -0.41 m w.eq. yr-1in the same time. Both series present slightly negative linear trend and subject to high interanual variability. The seasonal SMB results for both methods coincide in indicate a greater variability in the winter SMB series than the summer series. These results indicate this basic SMB model is able to reproduce 61% of the annual variance observed in the SMB measured of the Echaurren Norte glacierduring the study period.Anassessment of the SMB sensitivity of the glacier revealed precipitations variability constitutes the dominant factor modulating glacier annual mass balance,being the air temperature variability asecondary component.Finally,the performance analysis of this and another recently applied SBM model in the Echaurren Norte glaciersuggests that it is possible to estimate the annual variations of its mass balance from a representative climate record (air temperature and precipitations) and through asimplified description of the natural physical processes concurrent in the atmosphere-glacier interface.