A Quantitative Study of Ship Weather Avoidance in Response to the Evolution of Typhoon Merbok

During the period of September 10th through the 18th, 2022 a Tropical Depression formed in the central North Pacific, moved northeast, then north, strengthening into Tropical Storm Merbok and becoming a Typhoon. Next, Merbok rapidly transitioned into a massive extratropical cyclone across the western Aleutians and Bering Sea. Merbok cut across all of the Trans-Pacific shipping routes. Ships were forced to exercise weather avoidance procedures by significantly changing either their speed or course to avoid Merbok in both its tropical and extratropical phases. This avoidance caused a drastic increase in the time and distance it took for many of these ships to complete their voyages.

It is estimated that more than half of U.S. imports are transported by seagoing vessels. Many of these ships are transporting goods from across the Pacific Ocean. When these ships are forced to avoid dangerous weather conditions it costs both time and money, as well as potentially adding distance to the voyage and placing additional stress on supply chains. The purpose of this research project is to estimate the duration of delays in travel time, any added distance to the voyage, and the additional costs that were incurred by commercial shipping vessels traversing the Pacific during this time. As a reference, no cargo losses, damages, or vessel damages were reported by vessels during Merbok. Although weather avoidance practices do cost time, money, and add distance, in this case it was completely successful.

In order to estimate these impacts, shipboard Automatic Identification System (AIS) location data from this time period was used to determine the paths of all identified ships, and their locations at any given time. The AIS information was then used to determine decision points for each of the 126 ships within the data sample to determine when and where the vessel either drastically cut its speed or changed its route in order to avoid Merbok. Decision points were also used to estimate the lead time and distance from which the vessel would have intercepted Merbok. In addition, decision points were also used to determine the extent to which each ship experienced delays due to practicing avoidance. This was done by comparing the difference between the time the voyage would have taken if the ship did not need to alter speed or direction and the actual time it took to reach their destinations. Finally, these delays were used to calculate the additional cost for each ship due to practicing avoidance. Quantitative results of vessel actions will be presented along with a brief description of the evolution of Merbok from Tropical Depression to massive extratropical cyclone in the Bering Sea.