Metzner, Doreen, Krüger, Kirstin, Zanchettin, D., Toohey, Matthew and Timmreck, C. (2012) Southern Hemisphere Climate Response to an extremely large tropical Volcanic Eruption: Simulations with the MPI-ESM. [Poster] In: The Lübeck Retreat, Collaborative Research SFB 574 Volatiles and Fluids in Subduction Zones: Climate Feedback and Trigger Mechanisms for Natural Disasters. , 23.-25.05.2012, Lübeck . The Lübeck Retreat: final colloquium of SFB 574; May 23-25, 2012: program & abstracts. ; p. 19 .

Abstract

Using an Earth System Model, we investigate the potential Southern Hemisphere (SH) climate response to an extremely large volcanic eruption. The volcanic radiative forcing is calculated offline with a global aerosol model taken into account the formation and development of the volcanic aerosol size distribution from an initial stratospheric injection of 700 Mt SO2 corresponding to that estimated for the VEI>7 volcanic eruption of Los Chocoyos in Guatemala 84 ka BP. Due to the extremely large volcanic radiative forcing, the surface cools over almost the entire SH. A significant positive phase of the Southern Annual Mode (SAM), persisting for at least 12 months, characterizes the simulated posteruption
SH atmospheric circulation. Significant changes of surface temperature, precipitation and wind fields result from a distinct increase in magnitude and poleward movement in position of the SH westerlies. This is associated with temporary modifications in the upper ocean circulation in the Antarctic Circumpolar Current region. Due to the propagation of the forced anomalies into the deep ocean layers, the anomalous oceanic state persists well beyond the atmospheric response timescale. Significant negative temperature anomalies in the SH ocean propagate down to ~2000 m during the first ~20-50 post-eruption years, and persist for the entire simulated 200 years. A multicentennial anomaly in the SH ocean heat content represents the longest lived volcanically-forced signal detectable in the simulated climate.

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