Island Barrier Effects as Observed by Satellite and Instrumented Aircraft, and Simulated by a Numerical Model

Abstract

Examples of island barrier effects appearing in visual and infrared Defense Meteorological Satellite Program (DMSP) data are shown and documented with selected conventional and research aircraft data. Effects discussed include lee and corner, atmospheric and sea state changes, induced by trade-wind flow over island barriers under low-level temperature inversion conditions. The use of DMSP satellite infrared data in detecting atmospheric temperature and humidity changes in the vicinity of island barriers and of the visual sensor of DMSP in detecting changes in aerosol particle size distributions is introduced as an analytic technique with important potential for other types of weather analysis. In this study, the usefulness of DMSP infrared data in distinguishing blocked from non-blocked or partially blocked flow over an island is demonstrated. To aid in diagnosis of relevant phenomena, a two-dimensional (x?z) numerical model is applied to the task of simulating air flow over a nonblocked, flat heated island and predicting changes in downstream parameters. Included in the model?s physics are the diffusion, transport, growth and deposition of sea salt aerosol. The model is initialized based on data gathered by a research aircraft during the Hawaii Mesoscale Energy and Climate Project (HAMEC) during flights around the island of Hawaii in June 1980. Model results are compared to selected aircraft data and discussed in relationship to satellite observations.