Wind Estimation Around the Shipwreck of Oriental Star Based on Field Damage Surveys and Radar Observations

Oriental Star, a cruise ship with 454 tourists on board, capsized on the Yangtze River in Jianli County, Hubei Province, China, at about 2131 LST (LST = UTC + 0800) on June 1, 2015, leaving 442 fatalities. In the early evening on June 2, 2015, meteorological agency claimed that this accident was likely a result of tornado, based on a hasty diagnosis using limited information. This tornado claim was corrected to a microburst in the final official report issued by the government on 31 Dec. 2016, based on a detailed damage survey led by the first author of this abstract and more extensive analyses of many Chinese scientists including the authors. The objective of this work is to reveal what kind of weather phenomena occurred when the ship capsized and how strong the wind was around the wreck location, based on observational analyses and on-site ground and aerial damage surveys, in which drones were used for the first time in the meteorological damage survey history of China. Results demonstrate that the cruise ship capsized when it encountered strong winds at speeds of at least 31 m s^─1 near the apex of a bow echo embedded in a squall line. The bow echo caused a strong wind belt generally from the west to the east in an area of about 60 km by 60 km around the shipwreck location with multiple embedded microbursts. No radar-based tornado vortex signature or hook echo signature was found around the accident site. As suggested by the fallen trees within a 2-km radius around the wreck location, such strong winds were likely caused by microburst straight-line wind and/or embedded small vortices, rather than tornadoes.