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Nancy E. Westcott

1. Introduction Widespread dense fog can have large socioeconomic impacts through disruption of commerce and jeopardizing personal safety. Ground transportation can be severely affected. Low surface visibility can slow or delay ground transportation throughout the year and result in accidents. Data obtained from the Illinois Department of Transportation indicate that between 1975 and 1995 some 4000 collisions occurred annually under foggy conditions in Illinois, excluding the city of Chicago

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I. Gultepe, M. Pagowski, and J. Reid

1. Introduction Fog formation is related to thermodynamical, dynamical, radiative, aerosol, and microphysical processes, as well as surface conditions. Within fog, the extinction of radiation at visible ranges results in low visibilities that can affect low-level flight conditions, marine traveling, shipping, and transportation. The high frequency of fog occurrence, experienced greater than 10% of the time in some regions of Canada ( Whiffen 2001 ), requires improvements in fog nowcasting and

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Dustin Fabbian, Richard de Dear, and Stephen Lellyett

valid for 24 h. These forecasts are used by the commercial airlines and Air Services Australia (formerly the Civil Aviation Safety Authority) for flight planning, in-flight decision making, and optimization of airport operations. BoM staff routinely review their forecasting performance to seek ongoing improvement, and this study is part of a coordinated effort between Macquarie University and the BoM in relation to the latter’s National Fog Project. 2. Fog and aviation The main use of TAFs by

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Binbin Zhou and Jun Du

1. Introduction Fog is frequently blamed for traffic disasters and bad air quality in poor-visibility weather and has been extensively studied for more than a century (see the review by Gultepe et al. 2007 ). However, progress in the operational forecasting of fog at the National Centers for Environmental Prediction (NCEP) and other numerical weather prediction (NWP) centers has been slow due to the complexity of predicting fog and limited computing resources available for the task. For now

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Duo Yang, Harold Ritchie, Serge Desjardins, Garry Pearson, Allan MacAfee, and Ismail Gultepe

1. Introduction Fog is defined as a suspension of tiny water droplets (or ice crystals) in the atmosphere near the earth’s surface, lowering the visibility to less than 1 km; it is referred to as mist if the visibility is between 1 and 5 km ( WMO 1992 ). The base of the layer resting on the ground distinguishes fog from cloud. Fog near the surface typically contains a liquid water content of from 0.005 to 0.35 g m −3 ( Gultepe et al. 2009 ). It forms by cooling the air to its dewpoint, by

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Stevie Roquelaure, Robert Tardif, Samuel Remy, and Thierry Bergot

1. Introduction During the winter, airport authorities at Paris-Charles de Gaulle Airport, in Paris, France, are concerned with major management and safety issues caused by the occurrence of fog and low-ceiling events. Under these low-visibility conditions, low-visibility procedures (LVPs) are taken to safely manage the airport activity when visibility is less than 600 m and/or a ceiling is less than 60 m. Unfortunately, these procedures reduce by a factor of 2 the airport’s efficiency for

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Yongming Wang, Shanhong Gao, Gang Fu, Jilin Sun, and Suping Zhang

1. Introduction Fog that occurs over the ocean or a coastal region is usually termed sea fog. It significantly reduces low-level visibilities, which can play a role in severe marine accidents ( Trémant 1987 ; Gultepe et al. 2007 ). Sea fog is likely to form over regions where cold sea surface temperatures (SSTs) are adjacent to warm currents ( Lewis et al. 2004 ). The Yellow Sea of China (shown in Fig. 1 ), located north of the warm Kuroshio Current, is exactly such a region and experiences a

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A. Philip, T. Bergot, Y. Bouteloup, and F. Bouyssel

1. Introduction Operational short-term fog forecasting is a real challenge and has safety and economic impacts, especially for airports ( Gultepe et al. 2007 ). For security reasons, the air traffic control (ATC) authorities define a low visibility procedure (LVP) for horizontal visibilities of less than 600 m and/or ceilings of less than 60 m. During LVP conditions, the airport’s efficiency for takeoff and landing is reduced, causing flight delays and cancellations. For example, at Paris

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Stevie Roquelaure and Thierry Bergot

1. Introduction Over main international airports, forecasters have to deal with the prediction of infrequent events like fog and the life cycles of low clouds. At Paris’ Charles de Gaulle (CdG) international airport, adverse ceiling and visibility conditions (visibility under 600 m and/or ceiling below 60 m) lead to the application of low visibility procedures (LVPs). The application of LVPs reduces airport efficiency for takeoffs–landings by a factor of two, causing aircraft delays or

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Travis H. Wilson and Robert G. Fovell

1. Introduction Dense fog, whether over the land or sea, can have large socioeconomic impacts by disrupting travel and jeopardizing public safety ( Westcott 2007 ; Huang et al. 2015 ). Ten years’ worth of data (2004–13) obtained from California’s Internet Statewide Integrated Traffic Records System reveal that of the traffic accidents involving weather, only 10% are associated with fog but account for 28% of all weather-related fatalities ( CHP 2017 ). This makes travel in these conditions

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