The Freezing Spray Guidance web page shows estimates of ice accumulation in cm/hour on a vessel moving through the region at an average speed of about 20 knots (10 m/s), calculated using three different icing models. The models estimate the accumulation of ice from ship-generated spray using data from our forecast models (GFS, GFS-Wave, RTOFS, IMS Ice Analysis) combined with other physical parameters.

The ice accumulation rate is grouped into three categories, Low, Moderate, and Severe. The Overland and Stallabrass models use thresholds of

• Low: 0 to 0.7 cm/hr
• Moderate: 0.7 to 2 cm/hr
• Severe: > 2 cm/hr

The MINCOG model (Marine Icing model Norwegian COast Guard) uses slightly different categories for Low, Moderate, and Severe (Samuelson, 2017).

• Low: 0 to 0.5 cm/hr
• Moderate: 0.5 to 1.34 cm/hr
• Severe: > 1.34 cm/hr

Here is a presentation on Freezing Spray given at the 2024 OPC Mariner's Weather Hazards Workshop:

Understanding Maritime Freezing Spray, Forecasts, Risks and Hazards

References

Overland, J. E. (1990). Prediction of vessel icing for near-freezing sea temperatures. Weather and forecasting, 5(1), 62-77. https://journals.ametsoc.org/downloadpdf/journals/wefo/5/1/1520-0434_1990_005_0062_povifn_2_0_co_2.pdf

Desjardins, S. (2013). The Fetch Factor: Incorporating a fetch dependence into the Overland algorithm. National Lab for Marine and Coastal Meteorology, Environment Canada [WWW Document]. URL. https://ocean. weather. gov/icing_rates/FetchFactor_Overland. pdf.

Stallabrass, J. R., 1980: Trawler icing. A compilation of work done at NRC. Mechanical Engineering report MD-56, NRC No. 19372, National Research Council, Ottawa, Canada, 103 pp https://apps.dtic.mil/sti/tr/pdf/ADA100832.pdf

Samuelsen EM, Edvardsen K, Graversen RG. 2017. Modelled and observed sea-spray icing in Arctic-Norwegian waters. Cold Reg. Sci. Technol. 134: 54-81. https://dx.doi.org/10.1016/j.coldregions.2016.11.002