CHARACTERISTICS OF SUMMERTIME MARINE FOG OBSERVED FROM A SMALL REMOTE ISLAND
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Authors
Rowe, Kelsey M.
Subjects
coastal fog
fog microphysics
optical attenuation
visibility
fog optical properties
liquid water content
fog microphysics
optical attenuation
visibility
fog optical properties
liquid water content
Advisors
Wang, Qing
Ruiz-Plancarte, Jesus
Date of Issue
2023-06
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
This research is part of the Fog and Turbulence Interactions in the Marine Atmosphere (FATIMA) project focusing on the physical processes in marine fog and their impact on optical attenuation. This observational study is based on the measurements from Sable Island during the FATIMA Grand Banks field campaign. The analyses used the water droplet size distribution from a fog monitor (FM-120) and the meteorological optical range (MOR) measured by a present weather sensor (PWD22) as the main data source augmented by frequent radiosonde launches. Based on the 35 days of measurements, we identified nine reduced visibility events (RVEs). The radiosonde profiles revealed the complex layered thermodynamic structure within and above the fog layers and the frequent presence of high surface winds up to 16 ms-1 and a low-level jet, while the droplet spectra indicated a bimodal distribution below droplet size of 50 μm for most RVEs. Although the complete dataset under all weather conditions follows the same general trend of increasing MOR with decreasing liquid water content (LWC), the heavy fog events (visibility below 400 m) show different rates of decrease. We also found that representing both fog and mist using a single power function was unrealistic. Furthermore, the empirical relationship is sensitive to the length of averaging. Therefore, empirical functions derived from the nominal 1-min data may not be suitable for mesoscale models with a much coarser temporal output of LWC.
Type
Thesis
Description
Series/Report No
Department
Meteorology (MR)
Organization
Identifiers
NPS Report Number
Sponsors
Office of Naval Research (ONR, Arlington, VA 22217), Direct Energy Joint Transition Office (DEJTO, Albuquerque, NM 87106)
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Citation
Distribution Statement
Approved for public release. Distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.