Marine Fog Development Along the West Coast During 1973 Using Transient Ship and Coastal Station Observations

Marine Fog Development Along the West Coast During 1973 Using Transient Ship and Coastal Station Observations PDF

Author: George Stephen Evermann

Publisher:

Published: 1976

Total Pages: 216

ISBN-13:

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Using transient ship observations, a hypothetical five phase Marine Fog Development (MFD) Model was applied to four actual cases of summer marine fog during 1973 along the central California coast. The MFD Model incorporates a phase zero or synoptic phase and a proposed Coastal Convergence Zone (CCZ) concept into previous West Coast fog models. Phase zero describes the synoptic conditions that establish the marine layer over the coastal regions and explains the presence of low stratus over cast which normally exists prior to fog development cases. The CCZ concept defines a transition zone in which warm dry continental air converges with cool moist marine air and denotes the seaward extent of coastal influence. The location of the transitory CCZ is dependent upon the strength of offshore flow of continental air from the coastal region. The location where this flow meets the prevailing northwesterlies becomes the most likely site of marine fog formation. Selected synoptic scale meteorological parameters were examined and incorporated with transient ship and coastal station observations. This appeared to be an effective technique for tracking the CCZ and identifying fog phase development. (Author).

An Open-ocean Marine Fog Development and Forecast Model for Ocean Weather Station Papa

An Open-ocean Marine Fog Development and Forecast Model for Ocean Weather Station Papa PDF

Author: Robert Louis Clark

Publisher:

Published: 1981

Total Pages: 274

ISBN-13:

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Marine fog forecasts during the summer period in the North Pacific are not made presently with any acceptable degree of accuracy. Objective fog development models exist and are used with some success for localized coastal regions of the western U.S.; scarcity of accurate data has hindered creation of a reliable open-ocean model. The Eulerian single-station approach, utilizing a segment of the complete accurate data of Ocean Weather Station Papa (50N, 145W) is applied in this study to an objective marine fog forecasting model. The time-series study of significant atmospheric variables at OWS Papa, when coupled with a chronological synoptic overview, delineates accurately fog/no fog sequences in the summer months of 1973 and 1977. Actual observed fog situations are evaluated by the general model and presented in relation to open-ocean fog indices, NOAA 5 satellite coverage and synoptic history. The open-ocean forecast model is tested on an independent data set for the month of July 1975 at OWS Papa, with favorable results. The research delineates four required indices that must all be positive to forecast fog. These indices, when plotted daily in the region of OWS Papa allow a single station to predict, with some confidence out to twenty-four hours, the occurrence of advection fog. (Author).

Fog on the Central California Coast for 1973

Fog on the Central California Coast for 1973 PDF

Author: John William Beardsley

Publisher:

Published: 1976

Total Pages: 256

ISBN-13:

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Surface visibility data for selected stations on the central California coast in 1973 are analyzed. Radiosonde data from Oakland for the same period are used to derive meteorological indices. The year is divided into fog-related seasons, summer and winter, based on fog occurrence on the coast; and the seasonal and daily fluctuations of the indices are examined. A fog development model for the summer is formulated and compared to actual fog cases. In the winter, with far fewer coastal fog observations, the frequent occurrence of frontal passages prevents a standard development model from being formulated and compared. Four Oakland soundings are compared with four radiosondes taken at NPS Monterey, and the Oakland Soundings are found to closely approximate coastal conditions on these days. (Author).

Fog Sequences on the Central California Coast with Examples

Fog Sequences on the Central California Coast with Examples PDF

Author: Craig Allen Peterson

Publisher:

Published: 1975

Total Pages: 190

ISBN-13:

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In the low visibility range, forecasts during the summer period along the west coast of California are presently not made with any degree of accuracy. Modeling sequences associated with the nonfrontal fog formations during the summer period offer the possibility of improving fog diagnosis. Such sequences have been in use in Southern California for some time. This study uses a synoptic approach, focusing on sequences observed in the non-diurnal aspects of coastal fog. A development model is presented in order to delineate patterns of the fog phenomenon along the Central California coast. Actually observed fog situations are presented in order to evaluate the model and determine if day-to-day changes in specific non-diurnal indices represent trends which can aid forecasters. Results show that, although the model is general in nature, a correlation between the stages of the observed fog exists. The relationship of the time of occurrence of dense fog and the trends in the height of the inversion base and daily maximum temperatures at the top of the inversion and the inland valley are pointed out. (Author).

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