ALARM aims to provide a volcano module for the planned integrated medium term forecast system, which describes the formation and temporal development of the volcanic aerosol and the associated radiative forcing realistically.
When the next volcano erupts, large changes in the Earth system are to be expected. For instance, as a response to the 1991 eruption of Mt. Pinatubo, in the Philippines, global surface cooling with a maximum of about 0.4K was observed. But how predictable is the response of the Earth system to future eruptions? And how much will the response depend on factors such as the ocean state, or the season, location, and strength of the event? In the case of a large Pinatubo size volcanic eruption, any decadal scale climate prediction neglecting the effects of this eruption will have very limited forecast skill. Thus, the main goal of our project is to provide a volcano module for the planned integrated medium term forecast system which describes the formation and temporal development of the volcanic aerosol and the associated radiative forcing realistically. The module will be applicable immediately after an eruption when the major climate relevant eruption parameter (amount of sulfur released into the stratosphere) has become available from satellite observations or other volcanological estimations.
For any given volcanic eruption it has to be decided if this specific event calls for a new decadal term climate prediction. This requires the performance and analysis of a series of sensitivity simulations investigating the possible climate impact of volcanic eruptions depending on location, source strength, and season of the eruption, and on the state of the tropical ocean. The simulation of the Pinatubo eruption serves as an ideal experiment to evaluate the prediction skill of the medium term forecast system.