The cruise ship Oriental Star, with 454 people on board, capsized on the Yangtze River of China at ~2131 LST(Local Standard Time, LST=UTC+0800) on 1 June 2015, leaving 442 fatalities (Fig.1a and c). A recent study revealed the weather and wind situation when the shipwreck occurred.
The paper was titled "Wind Estimation around the Shipwreck of the 'Oriental Star' based on Field Damage Surveys and Radar Observations", which was published by the Science Bulletin in Vol.61, No. 4, with Dr. Zhiyong Meng of Peking University as the corresponding author. The authors solved the mystery of weather and strong winds near the shipwreck location when the disaster happened based on radar analyses and ground and aerial damage surveys.
From the very beginning of the event, there has been no agreement on what kind of weather the ship encountered. Since the horizontal scale of storms can be as small as several hundreds of meters, and the conventional meteorological observatories are so sparse that no direct wind observations were available within a distance of 13 km from the shipwreck location, and the nearest radar could only detect radial velocity higher than 700 m above ground level, the wind features at that moment can only be estimated from the damages to the trees and structures in help of radar observations.
This study investigated the wind and affecting weather systems around the shipwreck location based on radar analyses and ground and aerial damage surveys. The on-site damage surveys were performed for eight days under the collaboration of China Meteorological Administration, Universities, and Changjiang Maritime Safety Administration. The damages to the structure, trees, and crops were measured and recorded. Two drones were employed in aerial surveys to conduct a carpet monitoring in the severely damaged area especially near the shipwreck location by photograph and video shootings. The authors mentioned that this is the first time that drone was used in weather damage survey in the meteorological history of China.
The study showed that the ship was located near the apex of a bow echo embedded in a squall line (Fig.1c). Accompanied with the strengthening of strong heavy rainfall (Fig. 1d) and the rear-inflow jet (Fig.1e) of the bow-echo, the wind speed at ~ 700 m AGL ~ 1 km north of the wreck location increased to at least 22 m s-1 at 2127 LST (Fig.1f). Several places with apparent microburst damage were found within 10 km from the wreck location (Fig.2). Within 2 km from the shipwreck, most trees were found to fall southeastwards with curved tree fall patterns at a scale of about 30 m at several isolated places. These fallen trees were likely caused by microburst straight-line wind and/or embedded small vortices, rather than tornadoes. Based on a snapped tree only about 600 m from the shipwreck (Fig. 1b), it is estimated that Oriental Star encountered strong winds of at least 31 m s-1 when it capsized.
This research was funded by National Key Basic Research Program of China (No. 2013CB430100) and National Natural Science Funds for Distinguished Young Scholar (No. 41425018).
See the article: MENG Zhiyong, YAO Dan, BAI Lanqiang, ZHENG Yongguang, XUE Ming, ZHANG Xiaoling, ZHAO Kun. TIAN Fuyou, and WANG Mingjun, 2016: Wind Estimation around the Shipwreck of the "Oriental Star" Based on Field Damage Survey and Radar Observaions, Science Bulletin, 2016, Vol 61, No. 4: 330-337