10 The ABC-Pyramid: a scientific laboratory at 5079 m a.s.l. for the study of atmospheric composition change and climate

The Himalayan–Karakoram range is located in one of the most densely populated and very rapidly developing world areas. Monitoring of atmospheric composition in this area can play a relevant role in evaluating the background conditions of the free troposphere and quantifying the pollution present at high altitudes, as well as in studying regional and long-range transport phenomena. Due to technical and logistic difficulties in carrying out measurements at high altitude in the Himalaya, no systematic observations of atmospheric constituents are available for this area. Thus, a new measurement station in such a region represents a unique source of data, able to make up for the prior lack of this information. For these reasons, in the framework of the SHARE-Asia and ABC projects, a remote monitoring station, the ABC-Pyramid Laboratory, will be installed in the Khumbu valley near Mt. Everst at 5079 m a.s.l. Continuous in situ measurements of chemical, physical and optical properties of aerosol, surface ozone concentration, as well as non-continuous measurements of halocarbons and other greenhouse-gas concentrations will be carried out. This monitoring station was projected, realised and tested in Bologna at CNR-ISAC Institute during autumn 2005. It was designed to be controlled by remote login and to operate for the long-term in extremely adverse weather conditions. This station represents an ideal place for studying regional and long-range air mass transport, due to natural and human processes. Precious 5-day forecast information about air-masses circulation at the ABC-Pyramid site will be supplied daily by Lagrangian backward trajectories, including suitable forecasts of stratosphere-troposphere exchange phenomena.