Spatio-temporal variability of snow water equivalent in the extra-tropical Andes Cordillera from distributed energy balance modeling and remotely sensed snow cover

Abstract

Abstract. Seasonal snow cover is the primary water source for human use and ecosystems along the extratropical Andes Cordillera. Despite its importance, relatively little research has been devoted to understanding the properties, distribution and variability of this natural resource. This research provides high-resolution (500 m), daily distributed estimates of end-of-winter and spring snow water equivalent over a 152 000 km2 domain that includes the mountainous reaches of central Chile and Argentina. Remotely sensed fractional snow-covered area and other relevant forcings are combined with extrapolated data from meteorological stations and a simplified physically based energy balance model in order to obtain melt-season melt fluxes that are then aggregated to estimate the end-of-winter (or peak) snow water equivalent (SWE). Peak SWE estimates show an overall coefficient of determination R2 of 0.68 and RMSE of 274 mm compared to observations at 12 automatic snow water equivalent sensors distributed across the model domain, with R2 values between 0.32 and 0.88. Regional estimates of peak SWE accumulation show differential patterns strongly modulated by elevation, latitude and position relative to the continental divide. The spatial distribution of peak SWE shows that the 4000–5000 m a.s.l. elevation band is significant for snow accumulation, despite having a smaller surface area than the 3000–4000 m a.s.l. band. On average, maximum snow accumulation is observed in early September in the western Andes, and in early October on the eastern side of the continental divide. The results presented here have the potential of informing applications such as seasonal forecast model assessment and improvement, regional climate model validation, as well as evaluation of observational networks and water resource infrastructure development.

The 2010–2015 megadrought in central Chile: impacts on regional hydroclimate and vegetation

“…We employed a snow water equivalent (SWE) distributed reconstruction developed by Cornwell et al (2016) over the subtropical Andes for the period 2001-2015, fully independent of precipitation data. The SWE reconstruction combines information on fractional snow cover depletion obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on board the Terra and Aqua satellites (MOD10A1, Hall et al, 2010) and a physically based energy balance model that explicitly computes shortwave and longwave radiation, and adds a simplified parameterization of turbulent fluxes.…”

Mountain water cellars: a chemical characterization and quantification of the hydrological processes and contributions from snow, glaciers and groundwater to the Upper Mendoza River basin (~ 32° S), Argentina

“…Because of the limitations given by the climate and topography hold by one of the largest mountain ranges on the planet (Cornwell et al, 2016), these contributions have not been fully determined in the Central Andes. Without this knowledge, any input change from snow to ice calculation with models may be over-or under-estimated (Rodriguez et al, 2014).…”

“…The water supply for the oasis irrigated by the Mendoza River, in the northern part of the Mendoza Province, Argentina, has been under extraordinary pressure following the mega-drought that affected the Central Andes during the period -2015(CR 2 , 2015Cornwell et al, 2016;Gonzalez-Reyes et al, 2017). This basin is supplied mainly from snow contribution in years of normal to abundant loads (Masiokas et al, 2006), while from glacial and periglacial sources during drought events.…”

“…The different responses of ice bodies and snow to weather conditions also depend on the intrinsic properties of each solid water source, such as the albedo, density and thickness of snow or ice cover 20 and the amount and type of sediment contained in glaciers (Lliboutry, 1958;Paterson, 1969;Trombotto and Ahumada, 2005;Corripio et al, 2007;Pellicciotti et al, 2008). Because of the lack of precipitation during the melting period (Cornwell et al, 2016), the albedo of snow and ice remain almost constant, except during the transition from snow to ice (Pellicciotti et al, 2008). Consequently, the river flow is initially derived from snowmelt, followed by the contribution of ice bodies (Crespo et al, 2017).…”

“…Without this knowledge, any input change from snow to ice calculation with models may be over-or under-estimated (Rodriguez et al, 2014). About 70% of the waters of this basin are generated in the geological province of Cordillera Principal (DGI, 2006a) which in turn presents ideal conditions for the study of water delivered by glaciers, snow and groundwater due to the null forest cover, low 10 cloud cover and infrequent rainfall during the melting period (Cornwell et al, 2016).…”