2024 Volume 80 Issue 17 Article ID: 24-17271
Tugboats push the ferry against the quay to maintain cargo handling functions in case of agitation in the port of Tomakomai. The annual number of tugboats pushing ferries showed a positive correlation with the PDO index, and this paper discusses the relation between the wave powers and so on at the port for the period 1980 to 2021 and climatic indices which are PDO index, NPGO index and AO index. The major conclusions are as follows.
(1) The annual maximum wave power shows a positive correlation with the AO index before 1999 and the PDO index after 2000. The reason why is that the correlation between the AO index and the PDO index are getting weaker as strong in 1980's.
(2) Because typhoons are coming closer than before, the ratio of the annual maximum wave power more than 100 kW/m after 2000 is twice than before 1999.
(3) The annual frequency of waves that interfere with ferry cargo handling operations at the Tomakomai Port shows a positive correlation with the annual number of tugboats pushing ferries after 2000.