Himawari-8气象卫星黄海浒苔动态监测

Application of Himawari-8 Data to Enteromorpha Prolifera Dynamically Monitoring in the Yellow Sea

基于Himawari-8气象卫星数据,研究了利用归一化植被指数提取浒苔信息方法,并提出了浒苔强度和移动速度估算方法。对2016年5-7月黄海海域浒苔信息进行监测,获得了浒苔暴发的时间、地点、面积、强度、影响范围、漂移路径及移动速度。结果表明:2016年5月19日Himawari-8气象卫星首次监测到黄海海域出现浒苔信息;6月中下旬进入暴发期,浒苔面积、影响范围及强度达到最大值;7月上旬,伴随着浒苔大面积登陆青岛、烟台、威海等地,浒苔进人缓慢消亡阶段。多时次浒苔强度合成产品显示:2016年浒苔在黄海中部海域、烟台以东海域覆盖强度较大,在初始位置一带覆盖强度较小。浒苔漂移路径整体为从东南外海逐渐开始向西北近海海域靠近,日移动速度不断变化。浒苔的动态变化与水文气象环境密切相关,适宜的温度是浒苔生长和发展的基础,浒苔出现后,盛行风向是浒苔漂移方向的主要驱动力,2016年5-7月强劲的南风使浒苔一直向北漂移,并最终抵达威海,浒苔的移动与风向大致相同。

As a new generation geostationary meteorological satellite, Himawari-8 can provide measurements dynamically monitoring of Enteromorpha prolifera, with its high temporal-spatial resolution. According to the normalized differential vegetation index NDVI, by studying reflection characteristics of enteromorpha,a method using Himawari-8 data is proposed for enteromorpha information detection, drift speed and intensity estimation. Using the above methods, the outbreak processes of enteromorpha prolifera in the Yellow Sea from May to July in 2016 are monitored including the appearing time, location, areas, intensity, range of influence, drift path and drift speed. Results show that the enteromorpha are detected firstly on 19 May2016 in the Yellow Sea and areas are relatively small. It outbreaks in mid and late June with its continuous growth, and areas, range of influence and intensity all reach the maximum in this period. The enteromorpha enters recession period in early July near the coast of Shandong Province, the Yellow Sea, such as Qingdao, Yantai, Weihai and so on.The calculation shows that enteromorpha intensity changes with time, and multi-temporal enteromorpha intensity are accumulated into enteromorpha intensity synthetic product. The multi-temporal enteromorpha intensity synthetic product shows that enteromorpha intensity covers more in the central Yellow Sea and the east of Yantai waters, and less in initial position. The moving path of enteromorpha from appearance to disappearance shows that the drift path of enteromorpha is from the southeast open sea to the northwest offshore, and the average daily drift speed changes constantly.Dynamic changes of enteromorpha are closely related to the environmental hydro meteorological conditions, such as temperature, wind speed and direction. The suitable temperature is the basis for enteromorpha ＇s growth and development. In late May, enteromorpha growth are detected near the northern coast of Jiangsu Province firstly, where the temperature is stably 20℃. And then in early June, enteromorpha area increases rapidly with the increasing temperature, and then outbreaks in mid-June when the temperature reaches 20℃ in east of Shandong Peninsula sea. In early July, the average temperature of the Yellow Sea is above 25 ℃, making the enteromorpha decay and disappear gradually. It shows that dominant wind direction is the main driving force of enteromorpha drift, the calculation shows that enteromorpha drifts northward with large and steady south wind from May to July in 2016, and finally arrive in Weihai coast, and the moving direction is in line with the wind.