A New Dataset for Understanding and Modeling Snow Distribution in the Semi-arid Andes Cordillera

Several parameters have been proposed as indicators of snow water equivalent (SWE) spatial distribution. Elevation, aspect, slope and maximum upwind slope (MUS) are good examples of these parameters which attempt to describe the snow spatial behavior. However, the best modeling strategy remains case-specific and strongly depends on the spatial scale of the physical driving processes. These scales widely vary from micro-topography to atmospheric energy levels available for freezing and melting. In this work, we analyze manually collected snow depth and density data from several hill-slopes on three watersheds along the semi-arid Andes of central Chile (32°S-35°S). Scarce vegetation cover in the upper region allows to focus the analysis on sheltering, avalanching and large scale variations, neglecting the effects of snow interception and trapping by trees and shrubs. Three fieldwork campaigns were performed during the end of the accumulation season of year 2011 (end of August), obtaining measurements in a relatively wide range of elevation (2000 to 3900 masl) and latitude (32.4°S to 34.0°S). Results shows that on a regional (>100km) and watershed (2km-12km) extent, a relation between elevation and SWE is clear. On the watershed extent, this relation has a large degree of dispersion caused by different responses of facing hill-slopes and high local slope values. These amounts are roughly explained when the MUS parameter is used as a predictor for snow depth measurements that do not fit on the elevation gradient. From a geostatistical perspective, data from different watersheds and hill-slopes show very similar variograms with scale breaks of ~45m and sill coefficients of ~0.7 m2. These results follow from an ongoing effort to build a novel regional dataset for testing and implementing new modeling techniques for a better understanding of the spatial and temporal dynamics of snow in the extratropical Andes Cordillera.lt;img border=0 src="images/C21D-08_B.jpg">