There is still a considerable amount of work to be done before we understand the dominant processes influencing cross-shelf exchange. The existing observations suggest a wide variety of processes can make significant contributions to cross-shelf exchange. However, several encouraging trends are evident in the studies described here. First, observational capabilities for studying the continental shelf continue to expand. Examples include: an increased variety of information from satellites; an ability to make routine long-term measurements of conductivity allowing us to estimate time series of salinity and density; acoustic current meters which can remotely sense much of the water column over the shelf or more accurately make point measurements of current velocity; and the capability to make rapid surveys of currents, temperature and salinity using shipboard Acoustic Doppler Current Profilers and towed vehicles. Second, studies synthesizing a variety of observations, including measurements other than physical, such as geochemical and biological observations, are providing new insights into difficult problems. The CTZ study, described in Section 2.1, is a good example of the usefulness of this approach. Finally, numerical models provide a powerful tool for guiding and complementing observational studies, particularly in the case of complicated processes which are often poorly resolved by observations alone.
Acknowledgments. This paper benefitted from comments by R. Beardsley, K. Brink, D. Chapman, and G. Gawarkiewicz, all at Woods Hole Oceanographic Institution. This work was funded by the Ocean Sciences Division of the National Science Foundation under grant OCE-9115713 and by the Office of Naval Research Coastal Science Program under grant number N00014-89-J-1074. Woods Hole Oceanographic Institution contribution 8818.