A - C
The second Aerosol Characterization Experiment (ACE-2) took place from 16 June till 24 July, 1997, over the sub-tropical North-East Atlantic. The choice of the area and time period was based on the following considerations. The area is characterized by large scale subsidence and therefore by the existence of a distinct temperature inversion separating the marine boundary layer (MBL) from the free troposphere FT. Earlier observations (ASTEX, Prospero, Raes, ?) have shown that in he MBL of the N.E. Atlantic clean air alternates with anthropogenic pollution from Europe and possibly from N. America (ASTEX, McGovern, see discussion below). In the FT aloft, clean air masses alternate with mineral dust transported out of N. Africa (Propspero, Raes). The area thus offers opportunities for studying the characteristics of various aerosol types. Furthermore, the dynamics of the MBL in this area are reasonably well understood (ASTEX) so that Lagrangian experiments could be planned focusing on aerosol processing during transport over the ocean. In addition, the area offers good opportunities to study the interaction of aerosol! s with the low level MBL stratiform clouds. Objectives: 1. Determine the physical, chemical, radiative and cloud nucleating properties of the major aerosol types in the North Atlantic region and investigate the relationships between these properties. 2. Quantify the physical and chemical processes controlling the evolution of the major aerosol types and in particular their physical, chemical, radiative and cloud nucleating processes. 3. Develop procedures to extrapolate aerosol properties and processes from the local to regional and global scale, and assess the regional direct and indirect radiative forcing by aerosols in the North Atlantic region. For more information, link to "http://www.ei.jrc.it/ace2/tellusov.html" [Summary provided by Frank Raes 1, Timothy Bates 2, Ge' Verver 3, Daan Vogelenzang 3 and Marc Van Liedekerke1]
ACE-2