We have seen that coastal meteorology research can be divided into three groups: thermal effects, orographic influences and storms. While the latter are not specifically coastal phenomena they have a significant impact on the coastal environment. Recent research has largely focused on coastally-trapped events [e.g., Ellington et al., 1992], the interaction of mesoscale flows with topography [e.g., Overland and Bond, 1993], and coastal fronts [e.g., Doyle and Warner, 1993b]. The sea-breeze has been investigated generally in the context of understanding the origin of convection over the Florida peninsula [e.g., Nicholls et al., 1991], and air pollution in southern California [e.g., Hanna, 1991]. There has been relatively little progress in forecasting coastal phenomena, in part, because operational objective analyses have insufficient resolution to study or detect these events.
The coastal environment is complex, changes in topography, surface roughness, large horizontal gradients contribute to a highly reactive and responsive atmosphere-ocean system. The coastal region is influenced by many meteorological phenomena from air-sea interactions to intense large-scale storm systems. Our knowledge of the individual components of this system are often adequate and occasionally quite well-known. However, the coastal environment requires understanding of the interactions and feedbacks between the various processes that determine the weather and the ocean circulation. This environment is dominated by scales between 10 and 100 km and similar time scales in the ocean and the atmosphere, which offers new challenges to our understanding of meteorology and oceanography. It is apparent that many of the uncertainties in our understanding of coastal meteorology are the consequence of our lack of understanding of air flow in complex terrain, and the effect of horizontal inhomogeneities on the air flow, coastal ocean currents and interactions between the air and the sea. While advances are constantly being made with numerical models, our ability to forecast coastal meteorology depends largely on the quality of the data that are assimilated into the models. Offshore data are sparse or nonexistent in most coastal areas, which will continue to severely limit our ability to adequately predict coastal phenomena. Observations are biased toward the land and even with the installation of more comprehensive surface-based remote sensing systems (e.g., radars, lidars and Doppler profilers) the offshore regions will remain inaccessible.
Coastal meteorology was highlighted in the recent National Research Council review of the state of the science [ Rotunno et al., 1992]. The panel made a number of recommendations, including a complete reexamination of boundary layer processes in inhomogeneous conditions, high-density observations and numerical simulations of the land breeze, the sea-breeze and other thermal circulations, new investigations of ageostrophic dynamics to improve our understanding of orographic influences, observational, numerical and theoretical studies that focus on specific interactions between large scale weather systems and the coastal environment, and the use of advanced modeling and observational systems to address gas, aerosol and particulate dispersion in the range of 10 to 100 km of the shoreline. The panel noted that there is a relative lack of training of meteorology students in areas pertaining to coastal meteorology. The oceanographic community has recognized the importance of meteorology to understanding the processes that control the coastal ocean [e.g., Bane et al., 1990] and this has become an integral part of National Science Foundation planning for multidisciplinary studies in the coastal ocean [ Brink et al., 1992] and a component of the Coastal Ocean Prediction System (COPS) program [ Mooers, 1992]. Similarly, understanding the coastal atmosphere requires a multidisciplinary approach to combine research on air motions, cloud physics, aerosol dynamics, convection, air-sea gas exchange, surface waves and fluxes, boundary layer dynamics, and large scale storm systems to investigate interactions and feedbacks between these processes. Peter Hobbs, in the preface to the NRC review, highlighted the importance of understanding coastal meteorology. Nearly half of the U.S. population currently lives in coastal areas and this number is likely to exceed 127 million people in the next 20 years. A better understanding of coastal meteorology is of benefit to the nation, since it affects commerce, industry, transportation, health, safety, recreation and national defense.
Part of this paper is based on a National Research Council panel's report Coastal Meteorology, a Review of the State of the Science, National Academy Press, 1992. The panel members were Richard Rotunno (Chairman), Judith Curry, Christopher Fairall, Carl Friehe, Walter Lyons, James Overland, Roger Pielke, David Rogers and Steven Stage. The contributions of these panel members are greatly appreciated. This work was supported by the Office of Naval Research, Marine Meteorology Program (N00014-90-J-1265 and N00014-94-I-0232).