Modeling present and future ice covers in two Antarctic lakes

Sebastián Echeverría,Francisco Suárez,Mark B Hausner,Sebastián Vicuña,Nicolás Bambach

doi:10.1017/jog.2019.78

Abstract

AbstractAntarctic lakes with perennial ice covers provide the opportunity to investigate in-lake processes without direct atmospheric interaction, and to study their ice-cover sensitivity to climate conditions. In this study, a numerical model – driven by radiative, atmospheric and turbulent heat fluxes from the water body beneath the ice cover – was implemented to investigate the impact of climate change on the ice covers from two Antarctic lakes: west lobe of Lake Bonney (WLB) and Crooked Lake. Model results agreed well with measured ice thicknesses of both lakes (WLB – RMSE= 0.11 m over 16 years of data; Crooked Lake – RMSE= 0.07 m over 1 year of data), and had acceptable results with measured ablation data at WLB (RMSE= 0.28 m over 6 years). The differences between measured and modeled ablation occurred because the model does not consider interannual variability of the ice optical properties and seasonal changes of the lake's thermal structure. Results indicate that projected summer air temperatures will increase the ice-cover annual melting in WLB by 2050, but that the ice cover will remain perennial through the end of this century. Contrarily, at Crooked Lake the ice cover becomes ephemeral most likely due to the increase in air temperatures.

Highlights

Lakes are well known as sentinels of climate change as many of their physical, chemical and biological properties are sensitive to variations in meteorological and hydrological conditions (Laird and others, 1996; Adrian and others, 2009; Schindler, 2009)
There are no measurements of water temperature below the ice cover, so the sensible heat flux at the ice–water interface was adjusted by minimizing the root mean square error (RMSE) between the modeled and measured ice thickness
An ice-lake model was developed to determine the ice thickness evolution of two Antarctic lakes: west lobe of Lake Bonney (WLB) and Crooked Lake; under three different future climate deltas determined by the hybrid delta approach

Summary

Introduction

Lakes are well known as sentinels of climate change as many of their physical, chemical and biological properties are sensitive to variations in meteorological and hydrological conditions (Laird and others, 1996; Adrian and others, 2009; Schindler, 2009). The McMurdo Dry Valleys (MDVs) of Victoria Land, Antarctica (Fig. 1a), contain several lakes with these features, and are distinctly sensitive to climate variations as small perturbations can lead to extreme variations in the hydrologic regime; known as polar amplification phenomena (Dana and others, 1998; Fountain and others, 1998, 1999). This site was discovered by Scott (1905), who made observations of lake levels and their ice covers. Large meteorological and physical data of different lakes exist thanks to the expeditions made by the New Zealand Antarctic Program, and the United States, McMurdo Dry Valleys, Long Term Ecological Research (MCM-LTER) Program (Castendyk and others, 2016)

Methods

Results

Discussion

Conclusion