The spatial response of the climate system to explosive volcanic eruptions

Determining the spatial response of the climate system to volcanic forcing is of importance in the development of short-term climate prediction and in the assesment of anthropogenic factors such as global warming. The June 1991 eruption of the Phillippine volcano, Mount Pinatubo, provides an important opportunity to test existing understanding and extend previous emperical analyses of volcanic effect. We identify the spatial climate response to historic eruptions in the surface air temperature and mean-sea- level pressure record and use this information to assess the impact of the Pinatubo eruption. The Pinatubo eruption 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 agreement between the spatial patterns of tempurature and circulation anomalies 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 Northern Hemisphere during the first winter after the equatorial eruptions analysed, followed by widespread cooling, but limited change in the atmosphere circulation, during the subsquent 2 years.