Puerto Rico - 2002: Field Studies to Resolve Aerosol Processes

A number of questions remain concerning homogeneous aerosol formation by natural organics interacting with anthropogenic pollutants. For example, sea-salt aerosol in the presence of ozone has been proposed as a source of chlorine atoms in heterogeneous photochemical reactions. The potential for Cl to initiate oxidation of natural organics, such as monoterpene hydrocarbons, generating homogeneous nucleation or condensable material that contributes to aerosol loadings needs to be assessed. The nighttime reactions of ozone and nitrate radical can also result in monoterpene reactions that contribute to aerosol mass. We are currently planning field studies in Puerto Rico that will be aimed at assessing these aerosol issues and other atmospheric chemistry questions. Puerto Rico has a number of key features that make it very attractive for a field study of this sort. The principal feature is its very regular meteorology and position in the Caribbean Sea relative to the easterly trade winds. This meteorology and the rectangular shape (100 x 35 miles) of the island make it very suitable for simplification of boundary layer conditions. In addition, the long fetch between Puerto Rico and the nearest pollution sources in Africa and southern Europe make the incoming background air relatively clean and constant. This, plus the fact that Puerto Rico has approximately 3.5 million people and a very well defined source region and central area of rain forest vegetation, make it an ideal locale for assessing these aerosol processes. The region, its characteristics, and its emissions will be outlined and the proposed field study (part of a proposed DOE field effort in 2002) will be described in detail.