Coastal fog

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Please contact me if you would like a copy of the thesis. The following link provides a 4-page summary of the project.

Lundquist, J. D. and T. B. Bourcy, 2000. California and Oregon humidity and coastal fog. 14^th Conference on Boundary Layers and Turbulence. Aspen, Colorado.

Master’s Thesis Abstract:

In order to better understand fog occurrence along the California and Oregon coast, this study is broken into three parts. Chapter 1 explores the literature, including theories and previous studies. Chapter 2 examines meteorological data from coastal surface stations, radar profiler stations, cooperative observing stations, 700 hPa synoptic maps, and GOES 9 visible satellite images for the months of June to October 1996. Fog exhibits a strong diurnal cycle at all stations. When fog is present, surface temperatures and wind speeds are lower, MABL inversion strength is greater, inversion base heights are lower, and inversion top temperatures are higher. 700 hPa synoptic maps show a clear correlation of a weak high over California during fog events and a trough passing over the state during clearing, such that fog is about 30% less likely to occur when a trough exists above the study area. These relationships are demonstrated using summer-long averages and case studies.

Chapter 3 uses a one-dimensional, primitive equation, second-order turbulence closure model to test fog behavior under various initial conditions and forcings. Preliminary results show that the model is sensitive to initial profiles of temperature and moisture, to subsidence rates, to wind speed, and to entrainment across the inversion. The model’s current bulk flux algorithm unrealistically decreases the sensible and latent heat fluxes in near-saturated conditions preventing fog formation. After fixing these fluxes, the model more realistically recreates the diurnal cycle of fog formation and dissipation. Chapter 4 offers suggestions for future studies.