Capsule: A comprehensive multidisciplinary research program on coastal fog provides unique insights on its lifecycle and predictability barriers.

As several review papers have concluded, marine fog is imperfectly characterized, and quantitative visibility forecasts are difficult to produce accurately. Some unique measurements have been made offshore Newfoundland and Labrador of the climatology of occurrence and the microphysical characteristics of marine, or open-ocean, fog. Based on measurements made at an offshore installation over 21 years, the percent of time with visibilities less than 0.5 n mi or approximately 1 km (1 n mi ≈ 1.85 km) reaches 45% in July, with a low of about 5% during the winter. The occurrence of fog is mainly due to warm air advection, with the highest frequency occurring with wind directions from over the warm Gulf Stream, and with air temperatures about 2°C warmer than the sea surface temperature. There is no diurnal variation in the frequency of occurrence of fog. The microphysical properties of the fog have been documented in the summer time frame, with over 550 h of in situ measurements made offshore with fog liquid water content greater than 0.005 g m−3. The fog droplet number concentration spectra peaks near 6 μm, with a secondary peak near 25–40 μm, which typically contains most of the liquid water content. The median droplet concentration is approximately 70–100 cm−3. The microphysical spectra have been used to develop a new NWP visibility parameterization scheme, and this scheme is compared with other parameterizations currently in use.

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Fog in northern climates and Arctic environs can be a risk to helicopter operations and shipping interests, as are high seas from severe storms that frequent these regions. Visibility conditions and forecasts determine whether helicopters can safely land on offshore facilities, or if personnel will need to be transferred by ship. High sea state conditions can affect offshore oil and gas exploration and production operations, including drilling, logistics, crane operations and emergency response. A workshop on Metocean Monitoring and Forecasting for the Newfoundland & Labrador Offshore, held 22-24 September 2014, identified the need of improving the visibility and severe sea state forecasting for Grand Banks which can have a positive contribution to safety and operations in the harsh North Atlantic Canada offshore environment. This has led to an open and collaborative multi-year Metocean Research and Development Project that is presently in its third year. Some twenty government, academic, and industry agencies are participating in this project. Detailed buoy and offshore installations-based scientific measurements have been collected over the past three years where previously there has been a lack of good quality observations. A climatology of low visibility (less than 1km) events shows a high frequency (about 55% of the time) during summer months. A "conceptual model" of Grand Banks fog has been developed, that defines the physical conditions under which fog develops, is maintained, moves and dissipates. The conceptual model will be the basis for the development of new visibility prediction systems which currently are not well established or verified. High seas, with wave heights over 6m, occur more frequently during winter. Sea state prediction systems are being evaluated for severe ocean wave conditions where they have reduced predictive skill. Currently, work is underway to establish the accuracy and consistency of several existing visibility and sea state prediction systems. This paper will illustrate results from the climatological studies and some of the unique metocean monitoring data being collected. The forecasting techniques (e.g. numerical atmospheric and oceanic prediction models, satellite-based schemes, and rules based systems) being evaluated, are outlined.

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