Preprints
https://doi.org/10.5194/egusphere-2022-603
https://doi.org/10.5194/egusphere-2022-603
 
19 Jul 2022
19 Jul 2022
Status: this preprint is open for discussion.

Climatic control of the surface mass balance of the Patagonian Icefields

Tomás Carrasco-Escaff1,2, Maisa Rojas1,2, René Garreaud1,2, Deniz Bozkurt2,3, and Marius Schaefer4 Tomás Carrasco-Escaff et al.
  • 1Department of Geophysics, University of Chile, Santiago, Chile
  • 2Center of Climate and Resilience Research, University of Chile, Santiago, Chile
  • 3Department of Meteorology, University of Valparaíso, Valparaíso, Chile
  • 4Instituto de Ciencias Físicas y Matemáticas, Universidad Austral de Chile, Valdivia, Chile

Abstract. The Patagonian Icefields (Northern and Southern Patagonian Icefields) are the largest ice masses in the Andes Cordillera. Despite its importance, little is known about the main mechanisms that underpin the interaction between these ice masses and climate. Furthermore, the nature of large-scale climatic control over the surface mass variations of the Patagonian Icefields still remains unclear. The main aim of this study is to understand the present-day climatic control of the surface mass balance (SMB) of the Patagonian Icefields at interannual timescales, especially considering large-scale processes.

We modeled the present-day (1980–2015) glacioclimatic surface conditions for the southern Andes Cordillera by statistically downscaling the output from a regional climate model (RegCMv4) from a 10 km spatial resolution to a 450 m resolution grid, and then using the downscaled fields as input for a simplified SMB model. Series of spatially averaged modeled fields over the Patagonian Icefields were used to derive regression and correlation maps against fields from the ERA-Interim reanalysis.

Years of relatively high SMB are associated with the establishment of an anomalous low-pressure center near the Drake Passage, the Drake low, that induces an anomalous cyclonic circulation accompanied with enhanced westerlies impinging the Patagonian Icefields, which in turn leads to increases in the precipitation and the accumulation over the icefields. Also, the Drake low is thermodynamically maintained by a core of cold air that tends to reduce the ablation. Years of relatively low SMB are associated with the opposite conditions.

We found low dependence of the SMB on main atmospheric modes of variability (El Niño-Southern Oscillation, Southern Annular Mode), revealing a poor ability of the associated indices to reproduce interannual variability of the SMB. Instead, this study highlights the Drake Passage as a key region that has the potential to influence the SMB variability of the Patagonian Icefields.

Tomás Carrasco-Escaff et al.

Status: open (until 13 Sep 2022)

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Tomás Carrasco-Escaff et al.

Tomás Carrasco-Escaff et al.

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Short summary
In this study, we investigate the interplay between climate and the Patagonian Icefields. By modeling the glacioclimatic conditions of the Southern Andes, we found that the annual variations in net surface mass gain experienced by these icefields are mainly controlled by annual variations in the air pressure field observed near the Drake Passage. Little dependence on main modes of variability was found, suggesting the Drake Passage as a key region for understanding the Patagonian Icefields.