基于HJ-1A/1B的2014年黄海海域浒苔灾害时空分布

自2007年以来, 黄海海域每年的5月初～8月中下旬浒苔(Ulva prolifera)会周期性地暴发与消亡,导致海洋生态环境被破坏以及经济损失。利用2014 年的HJ-1A/1B遥感影像, 利用神经网络监督分类及RULE规则影像重分类动态阈值法, 对2014年的浒苔的漂移路径、各时期影响的海域面积、分布面积以及暴发高峰期的最大面积进行了动态监测。结果表明, 2014年浒苔持续时间为101 d, 5月中旬开始在江苏省盐城市近海出现零星斑点, 分布面积为2.299 km², 影响面积为1 744.799 km²; 6月初到6月中旬浒苔广泛分布于黄海海域, 分布面积扩大至1 367.145 km², 达到当年的峰值; 从6月下旬开始, 浒苔进入衰退期, 浒苔分布面积、相对聚集密度均急剧缩小, 但影响面积的峰值出现在该时期; 8月初消亡于青岛附近海岸, 8月20日遥感影像已难以监测到浒苔的存在。2014年黄海海域浒苔经过了“出现—发展—暴发—衰退—消亡”5个发展阶段。

Spatial and temporal variability of Ulva prolifera in the Yellow Sea, China in 2014

A recurrent floating green algae bloom has been detected in the Yellow Sea since 2007. The algae, Ulva prolifera, is non-toxic, but the massive accumulations can cause significant environmental damage and result in economic loss for the marine industry. In this study, we investigate the spatial and temporal patterns of U. prolifera green tides in the Yellow Sea during 2014 using HJ-1A/1B satellite images, Neural Network Supervised Classification (NNSC), and RULE Image classification threshold segmentation. Results show that a little U. prolifera was discovered in the sea adjacent to Yan Cheng and Jiangsu Province in mid-May, with a distribution area of 2.299 km² and an area of influence of 1 744.799 km². The bloom reached a maximum, 1 367.145 km², in mid-June and was widely distributed in the Yellow Sea. Distribution area and relative aggregation density decreased rapidly after the end of June, however, the area of influence reached a peak value. In early August U. prolifera died out around coastal of Qingdao and was absent from remote sensing images on August 20. It existed for about 101 days in total. The U. prolifera bloom experienced five successive stages, i.e. appearance, development, outbreak, recession, and demise. It drifted from the Yancheng coast of Jiangsu Province to the Qingdao coast of Shandong Province, and reached its farthest extent at the Yantai coast.