ATMOSPHERE-SURFACE EXCHANGE MEASUREMENTS

The exchange of various trace species and energy at the earth's surfac e plays an important role in climate, ecology, and human health and we lfare. Surface exchange measurements can be difficult to obtain yet ar e important to understand physical processes, assess environmental and global change impacts, and develop robust parameterizations of atmosp heric processes. The physics and turbulent structure of the atmospheri c boundary layer are reviewed as they contribute to dry surface exchan ge rates (fluxes). Micrometeorological, budget, and enclosure techniqu es used to measure or estimate surface fluxes are described, along wit h their respective advantages and limitations. Various measurement iss ues (such as site characteristics, sampling considerations, sensor att ributes, and flow distortion) impact on the ability to obtain represen tative surface-based and airborne flux data.