Robock and Liu, 1994 Robock, Alan and Yuhe Liu, 1994: The volcanic signal in Goddard Institute for Space Studies three-dimensional model simulations. J. Climate, 7, 44-55.

We have analyzed the transient calculations of the Goddard Institute for Space Studies general circulation model for the climatic signal of volcanic eruptions. By compositing the output for 2 different volcanoes for Scenario A and 5 different volcanoes for Scenario B, we suppress the natural variability and extract the volcanic signals.

Significant global mean surface air temperature cooling and precipitation reduction are found for several years following the eruptions, with larger changes in the Northern Hemisphere (NH) than in the Southern Hemisphere. The global-average temperature response lasts for more than four years, but the precipitation response disappears after three years. The largest cooling in the model occurs in the NH summer of the year after spring eruptions. Significant zonal-average temperature reductions begin in the tropics immediately after the eruptions and extend to 45°S - 45°N in the year after the eruptions. In the second year, cooling is still seen from 30°S to 30°N. Because of the low variability in this model as compared to the real world, these signals may appear more significant here than they would by attempting to isolate them using real data. The results suggest that volcanoes can enhance the drought in the Sahel. No evidence was found that stratospheric aerosols from the low-latitude volcanic eruptions can trigger ENSO events in this model.

Prepared by Alan Robock ( ) - Last updated on April 2, 1999