The atmospheric hydrological cycle in Antarctica – past and future

Details

Supervisors

Massonnet, François

Faculty

Faculté des sciences

Degree label

Master [120] en sciences physiques, à finalité approfondie

Abstract

The hydrological cycle sets the climate of polar regions through changes in surface albedo, ice sheet surface mass balance, sea surface temperature and salinity, in particular in Antarctica. Global warming is known to cause an intensification of the global hydrological cycle. A serious obstacle to a quantitative understanding of the Antarctic hydrological cycle is the lack of reliable observations. Recently, a new atmospheric reanalysis (ERA5) has been released by the European Centre for Medium-range Weather Forecasts. In parallel, a large database of historical and climate change projection simulations has become available through the Coupled Model Intercomparison Project, phase 6. Few specific studies exist in the field but no global study. Here, we document for the first time the seasonal state, year-to-year variability and long-term trends of the Antarctic atmospheric hydrological cycle by process and regions. We find that seasonal thermodynamic (temperature and sea ice) and dynamic (surface pressure) drivers explain the seasonal variability of the cycle. Our analysis indicates an intensification of the atmospheric hydrological cycle over the last four decades, largely driven by precipitation and moisture convergence changes (with little role for evaporation). Changes in temperature, sea ice, and surface pressure (SAM) explain this multi-year evolution of the processes. By analyzing the ACCESS-ESM1.5 data, we show that the atmospheric hydrological cycle is projected to intensify by the end of the century, with a leading role from moisture convergence (increasing by +22.1% compared to present-day levels), followed by precipitation (+18.5%) and evaporation (+10.4%). Our study could be a starting point for the study of the global freshwater cycle in Antarctica.