Interannual and Interseasonal Variability of Surface Energy and Mass Fluxes on Shallap Glacier, Cordillera Blanca, Retrieved from ERA-Interim Reanalysis Data

Abstract:

The glaciers of the Cordillera Blanca (Peru) mountain range are exposed to the strongest mode of interannual global variability: El Niño/Southern Oscillation (ENSO). Because of the sparse mas balance observations, the quantification of ENSO influence on tropical glaciers is difficult. The starting point of this study is a four-year long time series of distributed surface energy and mass balance (SEB/SMB) at Shallap Glacier, southern Cordillera Blanca, calculated using a process-based model driven by in-situ observations. We use these data to calibrate a fully automated regression-based statistical downscaling tool, developed especially to downscale the individual SEB/SMB fluxes from large-scale gridded atmospheric data on a monthly basis (in this study, ERA-Interim) and for regularly spaced altitude slices on the glacier. Albeit some limitations inherent to the mass balance model and to the statistical downscaling strategy, the skill of the model evaluated by leave-one-out cross-validation allows a robust evaluation of the ENSO influence on glacier SEB/SMB fluxes for the longer period 1980 – 2013. The presented downscaling tool can be applied easily to other glaciers and/or atmospheric datasets, providing a new way to extend observed SEB/SMB time series to much longer time scales.