Monitoring the regional and temporal variability of winter snowfall in the arid Andes using digital NOAA/AVHRR data

Abstract

This paper deals with the spatial distribution and the temporal variability of snowfall in the most arid part of the Andes (18°-28°S) during southern hemisphere winter (May-September). As the official precipitation data is of poor quality, analyses were carried out by means of digital image processing techniques, using NOAA/AVHRR satellitedata. Through analysis of 24 different snowfall events from six winters, a previously unknown spatial and temporal precipitation pattern in this remote and unexplored area was revealed. Snowfall is most abundant in the southernmost part of the research area and on the western side of the Andes, indicating the Pacific origin of the snowfall.Nevertheless, the typical snowfall pattern is modified during different periods of the winter. Three typical time periods could be defined and distinguished from one another. Each of these three periods is characterized by typical weather conditions (cold fronts and "cut-offs ") leading to a distinct snowfall pattern.As this study is part of a broader paleoclimatic project, the results will serve as a basis for paleoclimatic reconstruction of past climate. Only by knowing the modern circulation and precipitation patterns is it possible to interpret paleoclimatic signals and archives found in the study area (e.g. paleosol, moraines) correctly.

Origin and variability of oxygen and hydrogen isotopic composition of precipitation in the Central Andes: A review

“…The topography of the Central Andes controls the distribution of rainfall (Insel et al, 2009). Precipitation mostly concentrates in the eastern mountain range (cordillera), whereas from the inner Altiplano-Puna Plateau towards the west, conditions become increasingly arid (Fuenzalida and Rutllant, 1986;Herrera et al, 2018;Saavedra et al, 2018Saavedra et al, , 2017Vuille and Baumgartner, 1998). In the western Central Andes, rainfall diminishes sharply from east to west as elevation decrease (Houston and Hartley, 2003).…”

In-stream wetland deposits, megadroughts, and cultural change in the northern Atacama Desert, Chile

“…There are several mechanisms that can influence rainfall variability over the Pacific slope of the Central Andes (~15°–30°S)—the main recharge zone for groundwater in the Atacama Desert—as shown by paleoclimatic proxy records and through analysis of historic rainfall events. These include, but are not limited to, sea surface temperatures in the North Atlantic and the corresponding latitudinal displacement of the Intertropical Convergence Zone (ITCZ) (Placzek et al, 2013; Baker and Fritz, 2015), sea surface temperatures in the tropical Pacific and the strength of the Walker Circulation (Houston, 2006), the location of the Bolivian High and the relative contribution of moist air masses from the Amazon basin to the northeast and the Gran Chaco to the southeast associated with the SAMS (Lenters and Cook, 1997, 1999; Vuille and Keimig, 2004), and a possible contribution of air masses from cutoff low events from the westerlies (Vuille and Ammann, 1997; Vuille and Baumgartner, 1998; Garreaud et al, 2003; Garreaud et al, 2010). Although any of these factors may have enabled decadal- to centennial-scale droughts in the Atacama Desert capable of collapsing in-stream wetland systems, the magnitude and frequency of tropical Pacific sea surface temperatures and ENSO variability are perhaps the most likely candidates to influence Holocene precipitation and recharge through their effects on upper-air circulation that can block the westward advection of moist air masses during El Niño events and sustained El Niño conditions (Vuille, 1999; Houston, 2006).…”

Variability of precipitation in the Atacama Desert: its causes and hydrological impact

“…Standard rain gauges in use at these stations probably reflect only precipitation in the form of rainfall. Both snowfall at high elevations (Vuille and Ammann, 1997;Vuille and Baumgartner, 1998) and fog at low elevations (Aravena et al, 1989) are under-recorded. Furthermore, the gauges are located in sites with different exposure and aspect.…”