Near-surface scintillation in a coastal ocean region

Paul A. Frederickson; Kenneth L. Davidson; Carl R. Zeisse; Charles S. Bendall

doi:10.1117/12.363617

5 October 1999 Near-surface scintillation in a coastal ocean region

Paul A. Frederickson, Kenneth L. Davidson, Carl R. Zeisse, Charles S. Bendall

Proceedings Volume 3763, Propagation and Imaging through the Atmosphere III; (1999) https://doi.org/10.1117/12.363617
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1999, Denver, CO, United States

Abstract

Infrared scintillation measurements were obtained along a 7 km path over San Diego Bay concurrently with meteorological measurements obtained from a buoy at the midpoint of the path. Bulk estimates of the refractive index structure parameter C_n², were computed from the buoy data and compared with scintillation-derived C_n² values. The bulk C_n² estimates agreed well with the scintillation measurements in unstable conditions. In stable conditions the bulk C_n² estimates were higher than the scintillation data, by up to an order of magnitude on average. This disagreement may be due to the effects of ocean waves in decreasing the vertical temperature and humidity gradients in stable conditions from the assumed Monin-Obukhov similarity theory forms, resulting in bulk C_n² values that are too high. The bulk C_n² estimates decrease rapidly when the absolute air-sea temperature difference approaches small positive values. These predicted decreases in C_n² were not observed in the path-averaged scintillation measurements or in single-point turbulence measurements, demonstrating that bulk models which estimate structure parameters based on mean air-sea differences are not valid when the mean air-sea difference approaches zero. It is believed that obtaining a better understanding of surface wave modification of near- surface atmospheric gradients represents the most promising means toward improving the bulk model.

Citation Download Citation

Paul A. Frederickson, Kenneth L. Davidson, Carl R. Zeisse, and Charles S. Bendall "Near-surface scintillation in a coastal ocean region", Proc. SPIE 3763, Propagation and Imaging through the Atmosphere III, (5 October 1999); https://doi.org/10.1117/12.363617

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