An Operational Marine Fog Prediction Model
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An Operational Marine Fog Prediction Model
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Author : Jordan C. Alpert
language : en
Publisher:
Release Date : 1990
An Operational Marine Fog Prediction Model written by Jordan C. Alpert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with Fog categories.
A major concern to the National Weather Service marine operations is the problem of forecasting advection fogs at sea. Currently fog forecasts are issued using statistical methods only over the open ocean domain but no such system is available for coastal and offshore areas. We propose to use a partially diagnostic model, designed specifically for this problem, which relies on output fields from the global operational Medium Range Forecast (MRF) model. The boundary and initial conditions of moisture and temperature, as well as the MRF's horizontal wind predictions are interpolated to the fog model grid over an arbitrarily selected coastal and offshore ocean region. The moisture fields are used to prescribe a droplet size distribution and compute liquid water content, neither of which is accounted for in the global model. Fog development is governed by the droplet size distribution and advection and exchange of heat and moisture. A simple parameterization is used to describe the coefficients of evaporation and sensible heat exchange at the surface. Depletion of the fog is based on droplet fallout of the three categories of assumed droplet size. Comparison of three months of model results over the Atlantic seaboard with ship data show realistic forecasts of fogbound areas. The MRF initial conditions are used to update the fog model boundaries, thus supplying "perfect forecasts" for the fog model boundary conditions. Liquid water droplet concentrations are used to infer the relative intensity of fog and compare well with visibility reports from ship locations. It should be noted, however, that the verification of fog at sea is hampered by the limited amount of routinely available ship observations. The model also successfully predicted situations in which no fog was present when similarly verified with ship data. These results show that diagnostic models can be developed for specific regional applications based on numerical weather forecasts made with large scale global models.
Marine Fog Challenges And Advancements In Observations Modeling And Forecasting
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Author : Darko Koračin
language : en
Publisher: Springer
Release Date : 2017-01-28
Marine Fog Challenges And Advancements In Observations Modeling And Forecasting written by Darko Koračin and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-01-28 with Science categories.
This volume presents the history of marine fog research and applications, and discusses the physical processes leading to fog's formation, evolution, and dissipation. A special emphasis is on the challenges and advancements of fog observation and modeling as well as on efforts toward operational fog forecasting and linkages and feedbacks between marine fog and the environment.
Statistical Diagnostic Modeling Of Marine Fog Using Model Output Parameters
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Author : Brian Lee Van Orman
language : en
Publisher:
Release Date : 1977
Statistical Diagnostic Modeling Of Marine Fog Using Model Output Parameters written by Brian Lee Van Orman and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Fog categories.
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
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Author : Robert Louis Clark
language : en
Publisher:
Release Date : 1981
An Open Ocean Marine Fog Development And Forecast Model For Ocean Weather Station Papa written by Robert Louis Clark and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with Fog categories.
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).
An Evaluation Of Marine Fog Forecast Concepts And A Preliminary Design For A Marine Obscuration Forecast System
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Author : E. J. Mack
language : en
Publisher:
Release Date : 1983
An Evaluation Of Marine Fog Forecast Concepts And A Preliminary Design For A Marine Obscuration Forecast System written by E. J. Mack and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1983 with categories.
Calspan's studies produced phenomenological descriptions of at least five new fog types, provided realistic verification on which to base new numerical modeling techniques, and developed synoptic and statistical relationships which could be used in operational forecasting. Under the current contract, Calspan conducted an objective evaluation of these predictive approaches, along with a select group of numerical models, by testing against data sets derived from at-sea observational studies. The results of this evaluation demonstrated that, with high-quality data, certain models can provide operationally useful forecasts for marine obscuration. It is also concluded that new knowledge of the physics of marine fog occurrence can help optimize the application of various forecast techniques and also serve as a back-up forecast tool. As a chief objective of this investigation, we outlined a preliminary version of an obscuration forecast system which, when fully developed, would incorporate this new knowledge and delineate the application of specific numeric and/or synoptic and statistical approaches; i.e., the system would specify a forecast tool tailored to the attendant meteorological scenario and functional within operational constraints. This report summarizes the research effort and results which led to the conceptual design of this forecast system.
Numerical Prediction Of Marine Fog Using The Coupled Ocean Atmosphere Mesoscale Prediction System Coamps
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Author : John L. Dumas
language : en
Publisher:
Release Date : 2001-03-01
Numerical Prediction Of Marine Fog Using The Coupled Ocean Atmosphere Mesoscale Prediction System Coamps written by John L. Dumas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001-03-01 with categories.
The U.S. Navy's requirement for a computer prediction system for marine fog and stratus dates back to the 1970s when meteorological models were being introduced to the fleet. The Naval Research Laboratory's Coupled Ocean/ Atmosphere Mesoscale Prediction System (COAMPS) is a leap forward in the Navy's numerical modeling ability but it still does not show great skill in fog forecasting. COAMPS has been 'tuned', or adjusted for certain constants and parameterizations, so that it has the minimum error for the maximum area. This tuning is a common practice for all numerical models. The objective of this thesis is to determine if changes can be made to the existing COAMPS code based on reasonable physical experiments for a specific location to help solve the numerical fog forecasting problem. The effectiveness of these experiments was first measured by comparing a modeled cloud edge to satellite imagery of Monterey, California taken during a week in August 2000 under a variety of foggy conditions. Comparisons were also made with observations taken from an aircraft, land stations and a vertical profiler. The experiments, specifically those regarding changes to the autoconversion and turbulent kinetic energy schemes, showed that while a perfect solution has not been found, it is possible to modify the model physics codes and optimize its performance in a specific region.
Santa Ana Associated Offshore Fog
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Author : Douglas Allen Backes
language : en
Publisher:
Release Date : 1977
Santa Ana Associated Offshore Fog written by Douglas Allen Backes and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1977 with Fog categories.
Aircraft measurements made offshore during a coastal fog sequence by R.A. Markson are analyzed. Fog occurrence and areal extent are determined using aircraft, ship and shore station observations obtained during the Cooperative Experiment in West Coast Oceanography and Meteorology--1976 along with analyzed satellite visual and infra-red imagery. The offshore conditions are compared with those at the shore stations using selected fog indices. Photographs of special features observed are included. The offshore conditions are classified into phases by assigning limits within the specified fog indices used in the modified Leipper fog model. The sequence of observed fog events is compared to the ideal sequence. The trends in the sequence are analyzed and a general relationship between the phase sequence and the local offshore flow is indicated. The Leipper indices, the San Diego raob and the sequential fog model appear to be useful in fog prediction for the nearshore oceanic region from San Diego the Point Conception. (Author).
Estimating Surface Currents In The Slope Water Region Between 37 And 41 N Using Satellite Feature Tracking
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Author :
language : en
Publisher:
Release Date : 1992
Estimating Surface Currents In The Slope Water Region Between 37 And 41 N Using Satellite Feature Tracking written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Ocean currents categories.
Forecasting Marine Fog On The West Coast Of The United States Using A Linear Discriminant Analysis Approach
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Author : Michael Charles McConnell
language : en
Publisher:
Release Date : 1975
Forecasting Marine Fog On The West Coast Of The United States Using A Linear Discriminant Analysis Approach written by Michael Charles McConnell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1975 with Fog categories.
Studying Marine Fog Using Weather Research And Forecast Wrf Model
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Author : Zheqi Chen
language : en
Publisher:
Release Date : 2021
Studying Marine Fog Using Weather Research And Forecast Wrf Model written by Zheqi Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with categories.
Fog can seriously affect daily life. However, due to the complex mechanisms involved, accurate and in time fog forecasts are still difficult. This study has used the Weather Research and Forecast model (WRF) to simulate marine advection fog over Sable Island, NS in summer 2018. Chapter 2 uses the real case simulation to find a good physics parameterization and apply it as a daily forecast. The results show that the model tends to give much lower visibility than observations on this small offshore island. Chapter 3 uses the single column model to simulate an advection fog. Different gravitational settling options have been examined, and it is found that the turbulent deposition can be a good solution to the problem. In Chapter 4 the turbulent deposition is tested in the real case simulation. The results show that the visibility can become higher, but further study is needed.