PhD Student

Email: moritz.guenther@we dont want

Telephone: +49-40-41173-386

Room: 429

Max Planck Institut for Meteorology
Bundesstraße 53
D - 20146 Hamburg

Atmosphere in the Earth System

Global Circulation and Climate, Stratospheric Forcing and Climate


Efficacy of volcanic radiative forcing: After volcanic eruptions, an aerosol layer forms in the stratosphere, reflecting parts of the incoming short wave radiation and thus cooling the earth. The resulting cooling is less than expected, judging from the emerging energy imbalance and comparing to the relatively well understood reaction of the earth system to CO2 forcing. This is measured by the so-called "efficacy". Using climate models, I want to elaborate the reasons for this. Furthermore, it remains to be understood which atmospheric adjustments happen as a consequence to the aerosol forcing.


Questions: What is the relationship between instantaneous and effective forcing for volcanic aerosols? Why is the temperature response to a volcanic aerosol forcing small when compared to an equivalent CO2-caused forcing, i.e. why is the efficacy lower than one? Which adjustments constitute the difference between instantaneous and effective forcing and what feedbacks cause the efficacy to be different from unity? What conclusions can be inferred for the earth system's climate sensitivity? In short: Which processes in the atmosphere are unique to volcanic aerosol forcing?