The Andes Cordillera. Part I: snow distribution, properties, and trends (1979–2014)

Abstract

Snow cover presence, duration, properties, and water amount play a major role in Earth's climate system through its impact on the surface energy budget. Snow cover conditions and trends (1979–2014) were simulated for South America – for the entire Andes Cordillera. Recent data sets and SnowModel developments allow relatively high‐resolutions of 3‐h time step and 4‐km horizontal grid increment for this domain. US Geological Survey's Global Multi‐resolution Terrain Elevation Data 2010 topography, Global Land Cover (GlobCover), Randolph Glacier Inventory (v. 4.0) glacier, and NASA modern‐era retrospective analysis for research and applications data sets were used to simulate first‐order atmospheric forcing (e.g. near‐surface air temperature and precipitation, including the fraction of precipitation falling as snow) and terrestrial snow characteristics (e.g. snow cover days, snow water equivalent depth, and snow density). Simulated snow conditions were verified against moderate‐resolution imaging spectroradiometer‐derived snow cover extent and 3064 individual direct observations of snow depths. Regional variability in mean annual air temperature occurred: positive trends in general were seen in the high Andes Cordillera, and negative trends at relatively lower elevations both east and west of the Cordillera. Snow precipitation showed more heterogeneous patterns than air temperature due to the influence from atmospheric conditions, topography, and orography. Overall, for the Cordillera, much of the area north of 23°S had a decrease in the number of snow cover days, while the southern half experienced the opposite. The snow cover extent changed ∼−15% during the simulation period, mostly between the elevations of ∼3000 and 5000 m above sea level (a.s.l.). However, below 1000 m a.s.l. (in Patagonia) the snow cover extent increased. The snow properties varied over short distances both along and across the Andes Cordillera.

Spatio-Temporal Patterns of the 2010–2015 Extreme Hydrological Drought across the Central Andes, Argentina

“…Recent negative trends in snow cover extent during 1979-2014 were mainly attributed to changes between 3000 and 5000 m a.s.l. [56], and can be responsible for the recent trends in streamflow across the CAA. Further studies are needed to properly quantify the role of the Pacific Decadal Oscillation (PDO) in the 2010-2015 hydrological drought, considering longer streamflow records to adequately represent the interdecadal variability.…”

Surface Air Temperature Fluctuations and Lapse Rates on Olivares Gamma Glacier, Rio Olivares Basin, Central Chile, from a Novel Meteorological Sensor Network

“…This is a visible response to climate variability and climate change, or more specifically changes in precipitation/snow accumulation and atmospheric warming. Glaciers in Central Chile in the central dry Andes have shrunk and retreated rapidly during the last few decades due to a warming climate [7][8][9], with serious impacts on water resources including drinking water and water for irrigation purposes, hydroelectric power, and future global and regional sea-level rise [10]. In Central Chile the most notable feature of the changing climate from 1979 to 2006 was a strong contrast between the coastal region (surface cooling: −0.2…”

Surface velocity fluctuations for Glaciar Universidad, central Chile, between 1967 and 2015

“…However, the influence of increased precipitation on glacier mass-balance conditions in the central Andes Cordillera has likely been offset through time by rising air temperatures reducing the amount of precipitation falling as snow. Falvey and Garreaud (2009) and Mernild and others (2016), for example, observed warming rates of 0.25°C (10 a) −1 between 1976 and 2006. Furthermore, in the 1990s, air temperature increase for the central Andes Cordillera coincided with a number of extreme drought events in central Chile (Quintana, 2000), which may have brought about negative mass-balance conditions, accounting for the reduced ice velocities observed for Glaciar Universidad during this period.…”