THE SPATIAL RESPONSE OF THE CLIMATE SYSTEM TO EXPLOSIVE VOLCANIC-ERUPTIONS

Determining the spatial response of the climate system to volcanic for cing is of importance in the development of short-term climate predict ion and in the assessment of anthropogenic factors such as global warm ing. The June 1991 eruption of the Philippine volcano, Mount Pinatubo, provides an important opportunity to test existing understanding and extend previous empirical analyses of the volcanic effect. We identify the spatial climate response to major historic eruptions in the surfa ce air temperature and mean-sea-level pressure record and use this inf ormation to assess the impact of the Pinatubo eruption. The Pinatubo e ruption clearly generated significant global cooling during the years after the event. The magnitude and timing of the cooling is similar to that associated with previous equatorial eruptions. There is good agr eement between the spatial patterns of temperature and circulation ano malies associated with the historic eruptions and those following the Mount Pinatubo event. Evidence of limited higher latitude warming and a major change in the atmospheric circulation is found over the Northe rn Hemisphere during the first winter after the equatorial eruptions a nalysed, followed by widespread cooling, but limited change in the atm osphere circulation, during the subsequent 2 years.