Joint Probability Analysis and Prediction of Sea Ice Conditions in Liaodong Bay

Sea ice conditions in Liaodong Bay of China are often described by sea ice grades,which classify annual sea ice conditions based on the annual maximum sea ice thickness(AM-SIT)and annual maximum floating ice extent(AM-FIE).The joint probability distribution of AM-SIT and AM-FIE was established on the basis of their data pairs from 1949/1950 to 2019/2020 in Liaodong Bay.The joint intensity index of the sea ice condition in the current year is calculated,and the joint classification criteria of the sea ice grades in past years are established on the basis of the joint intensity index series.A comparison of the joint criteria with the 1973 and 2022 criteria revealed that the joint criteria of the sea ice grade match well,and the joint intensity index can be used to quantify the sea ice condition over the years.A time series analysis of the sea ice grades and the joint intensity index sequences based on the joint criteria are then performed.Results show a decreasing trend of the sea ice condition from 1949/1950 to 2019/2020,a mutation in 1990/1991,and a period of approximately 91 years of the sea ice condition.In addition,the Gray-Markov model(GMM)is applied to predict the joint sea ice grade and the joint intensity index of the sea ice condition series in future years,and the error between the results and the actual sea ice condition in 2020/2021 is small.

Simulation of ice accumulation around bridge piers during river breakup periods using a discrete element model

During river breakup periods in winter or early spring, a large amount of ice floes of various sizes will be transported by flowing water. The presence of bridge piers in water alters velocity field. As a consequence, the transport process of ice floes around bridge piers will be influenced. It often causes the ice floe congestion around bridge piers. In the present study, the influences of the ice floe size and coverage ratio of ice floating on water surface on ice floe congestion have been examined. The influence of bridge pier layout on ice jam development has been assessed. Results showed that during river breakup period, the ice floe transport capacity around bridge pier decreased. With the presence of bridge piers, the critical coverage ratio of ice floating on water surface for the ice floe congestion depends on the ratio of the side length of ice floe to the pier spacing distance (a / Ln) and ice floe-length Froude number associated with the ice floe length (Fra). A discrete element model (DEM) has been developed to simulate the ice floe accumulating process around bridge piers. Simulation results agree well with those of experiments.