Volcanic activity parameters and volcanism-climate relationships within the recent centuries

Abstract

The ejecta ofvolcanism, including gas-to-particle conversions, form atmospheric aerosol layers which influence the radiation processes and in consequence the climate. Thereby, the major explosive eruptions are of predominant interest. They cause stratospheric warmings whereas the atmospheric boundary layer near surface is cooled. In order to study these effects, focussed on air temperature variations within the recent centuries (stratosphere only since 1958) a new volcanic activity index "SVI" is denned based on the Smithsonian volcano chronology. This parameter is compared with other similar parameters and used for an stratosphere-troposphere analysis of volcanic forcing. A long-term statistical analysis uses correlation and coherence techniques "integrated" and moving with time, considering the annual and 10 yr low-pass filtered data. The air temperature time series refer to the Northern Hemisphere and Arctic mean as well as to the stations Philadelphia (USA) and Hohenpeissenberg (FRG). In general, the long-term volcanism-climate relationships may be more pronounced than singular events. Finally, a moving signal analysis is performed where the volcanic signals in climate and the signal-to-noise ratios exceed the 95% confidence level in some cases.