Transient Ship Synoptic Reports

Transient Ship Synoptic Reports PDF

Author: Joseph Austin Schrock

Publisher:

Published: 1976

Total Pages: 308

ISBN-13:

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Coastal fog studies have always alluded to offshore marine fog development by extending known observations along the coast seaward. This velocity study attempts to establish the offshore conditions during one such coastal fog study through the analysis of transient ship synoptic reports. Over 1400 ship reports occurring off the coasts of California, Oregon, and Washington during two weeks in August 1974 and one week in December 1975 were analyzed. The visibility-weather group elements of the ship reports along with daily NOAA II satellite photographs were used to establish fog location and boundaries. Other Synoptic parameters such as air temperature, pressure patterns and sea surface temperature were studied in an attempt to determine reasons for marine fog development. An evaluation of the credibility and reliability of transient ship synoptic reports also was made.

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).

Climatological Marine-fog Frequencies Derived from a Synthesis of the Visibility-weather Group Elements of the Transient-ship Synoptic Reports

Climatological Marine-fog Frequencies Derived from a Synthesis of the Visibility-weather Group Elements of the Transient-ship Synoptic Reports PDF

Author: Robert J. Renard

Publisher:

Published: 1975

Total Pages: 64

ISBN-13:

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The study presents the essentials of a method of synthesizing the visibility-weather group elements of marine synoptic reports into a computerized scheme for the purpose of deriving frequencies of marine-fog occurrence. The program, based on an interpretation of reporting guidelines in the Synoptic Code Manual, uses 16 combinations of present and past weather, and visibility, to identify fog in the reports. The program then objectively assigns the duration of fog for the period represented by each of the reports. A prototype climatology of marine-fog occurrence for July, over the North Pacific Ocean, is derived from application of the method to a ten-year data base (1963-72). Results are compared and discussed in relation to other published coastal and marine-fog climatologies. Diurnal fog frequencies at sea and the compatibility of fog observations from Ocean Weather Stations and transient ships are also treated. The continuing work and its goals are described.

Statistical Diagnostic Modeling of Marine Fog Using Model Output Parameters

Statistical Diagnostic Modeling of Marine Fog Using Model Output Parameters PDF

Author: Brian Lee Van Orman

Publisher:

Published: 1977

Total Pages: 204

ISBN-13:

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Diagnostic model output parameters, provided by the Fleet Numerical Weather Central, Monterey, Calif. (FNWC), and the marine fog frequency climatology developed at the Naval Postgraduate School, are statistically processed in context with marine surface synoptic ship reports in order to develop a linear regression scheme to model distribution of marine fog. The study area includes a large section of the North Pacific Ocean (from 30-60N) at 0000 GMT, 1-30 July 1976. The diagnostic capabilities of the regression equations are analyzed through the use of three verification scoring systems. Improvement over climatology and FNWC's operational fog probability program (FTER), is demonstrated. Selective mappings of the regression equation outputs and categorized observations are intercompared with the sea-level pressure analysis; FTER; and the evaporative heat flux--the most significant predictor parameter.

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 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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