Isotopic anomalies in water vapor during an atmospheric river event at Dome C, East Antarctic plateau, controlled by large-scale advection and boundary layer processes
*Cécile Agosta [1], Cécile Davrinche ****[1], Christophe Leroy-Dos Santos ****[1], Antoine Berchet ****[1], Amaëlle Landais ****[1], Elise Fourré ****[1], Anaïs Orsi ****[1, 2], Frédéric Prié ****[1], Charles Amory ***[3, 4], Vincent Favier [3], Xavier Fettweis [4], Christophe Genthon [5], Christoph Kittel [4], Dana Veron [6], and Jonathan Wille [3]
Sea Level Rise Seminar, 2021-03-16: Cecile Agosta
Antarctic surface mass balance: local and large-scale drivers, present and future.
Cécile Agosta, with Christoph Kittel, Charles Amory and Jonathan Wille
The Antarctic surface mass balance mainly consists in mass gains by snow accumulation (snowfall minus sublimation and drifting snow) and mass loss by meltwater run-off. Snow accumulation is supposed to increase in a warming climate, but this term remains a major source of uncertainty for projections of the Antarctic contribution to sea-level. Surface melt is currently mostly negligible but is also expected to increase in the future, which could lead to ice shelves instability, reduced buttressing effect and accelerating ice discharge into the ocean.Here we present the main drivers of the Antarctic surface mass balance, focusing on snow accumulation and meltwater run-off. We detail the local polar processes impacting both terms and then assess the role of large-scale circulation with emphasis on extreme advection events (atmospheric rivers). As both large-scale and local processes are critical to correctly model the Antarctic surface mass balance, we first evaluate large-scale fields of CMIP global climate models over the Southern Ocean and then use a polar-oriented regional climate model to perform projections over the 21st century. Over the grounded ice sheet the surface mass balance is projected to increase as a response to stronger snowfall for all scenarios, which will mitigate ice losses, while over ice shelves surface mass balance will strongly decrease for Antarctic warmings larger than +2.5 °C (relative to 1981-2010) because of significant increase in meltwater run-off, which could impact ice shelves stability. Future work will be dedicated to better quantifying past climate variability and leading polar processes using surface mass balance and water isotope constraints, in the aim of further improving Antarctic climate projections.
Antarctic surface mass balance: local and large-scale drivers, present and future
Antarctic surface mass balance: local and large-scale drivers, present and future Here we present some of the main drivers of the Antarctic surface mass balance, focusing on snow accumulation and meltwater run-off. We detail the local processes impacting both terms and then assess the role of large-scale circulation with emphasis on extreme advection events. As both large- scale and local processes are critical to correctly model the Antarctic surface mass balance, we evaluate large-scale fields from CMIP global climate models over the Southern Ocean and then use a polar-oriented regional climate model to perform projections over the 21st century. We show increased snow accumulation over the grounded ice sheet for all scenarios that will mitigate ice losses, while meltwater run-off will significantly increase over ice shelves, causing strongly decreased surface mass balance over ice-shelves that could impact their stability. Future work will be dedicated to better quantifying past climate variability by combining surface mass balance and water isotope constraints and to broaden multi-model projections of the Antarctic surface mass balance.
Ongoing...