Abstract
The origin of moisture for the Southern Patagonia Icefield and the transport of moisture towards it are not yet fully understood. These quantities have a large impact on the stable isotope composition of the icefield, adjacent lakes and nearby vegetation, and is hard to quantify from observations. Clearly identified moisture sources help to interpret anomalies in the stable isotope compositions and contribute to paleoclimatological records from the icefield and the close surrounding. This study detects the moisture sources of the icefield with a Lagrangian moisture source method. The kinematic 18-day backward trajectory calculations use reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA-Interim) from January 1979 to January 2017. The dominant moisture sources are found in the South Pacific Ocean from 80◦ W to 160◦ W and 30◦S to 60◦ S. A persistent anticyclone in the subtropics and advection of moist air by the prevailing westerlies are the principal flow patterns. Most of the moisture travels less than 10 days to reach the icefield. The majority of the trajectories originate from above the planetary boundary layer but enter the Pacific boundary layer to reach the maximum moisture uptake 2 days before arrival. During the last day trajectories rise as they encounter topography. The location of the moisture sources are influenced by seasons, Antarctic Oscillation, El-Nino Southern Oscillation, and the amount of monthly precipitation, which can be explained by variations in the location and strength of the westerly wind belt.”
Highlights
The Southern Patagonia Icefield is the biggest temperate ice mass in the Southern Hemisphere, and an important fresh water storage for southern South America
This study presents a diagnostic picture of the moisture source regions from the icefield, the average transport time of moisture and favored pathways
The mean moisture sources are derived from the Lagrangian methodology and represent the mean moisture uptake within the scaled planetary boundary layer (PBL), which contributes to the monthly precipitation in the icefield averaged over the time period from February 1979 to January 2017 (Figure 5)
Summary
The Southern Patagonia Icefield is the biggest temperate ice mass in the Southern Hemisphere, and an important fresh water storage for southern South America. It is located at the southern end of the Andes cordillera between 48.3 and 51.0◦S along 73.0◦W with an average width of 30– 40 km and the narrowest section being 8 km wide (Figure 1) (Aniya et al, 1996). Extreme environmental conditions and inaccessibility of the icefield pose a challenge for scientists to acquire records of meteorological conditions. Moisture Sources of the Southern Patagonia Icefield
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