South China Sea Marine Prediction Center, State Oceanic Administration, Guangzhou, China.
Key Laboratory of Marine Environmental Survey Technology and Application, Ministry of Natural Resources, MNR, Guangzhou, China.
Sci Rep. 2021 May 13;11(1):10238. doi: 10.1038/s41598-021-89649-8.
A coastal front was detected in the eastern Guangdong (EGD) coastal waters during a downwelling-favorable wind period by using the diffuse attenuation coefficient at 490 nm (K(490)). Long-term satellite data, meteorological data and hydrographic data collected from 2003 to 2017 were jointly utilized to analyze the environmental factors affecting coastal fronts. The intensities of the coastal fronts were found to be associated with the downwelling intensity. The monthly mean K(490) anomalies in shallow coastal waters less than 25 m deep along the EGD coast and the monthly mean Ekman pumping velocities retrieved by the ERA5 dataset were negatively correlated, with a Pearson correlation of - 0.71. The fronts started in October, became weaker and gradually disappeared after January, extending southwestward from the southeastern coast of Guangdong Province to the Wanshan Archipelago in the South China Sea (SCS). The cross-frontal differences in the mean K(490) values could reach 3.7 m. Noticeable peaks were found in the meridional distribution of the mean K(490) values at 22.5°N and 22.2°N and in the zonal distribution of the mean K(490) values at 114.7°E and 114.4°E. The peaks tended to narrow as the latitude increased. The average coastal surface currents obtained from the global Hybrid Coordinate Ocean Model (HYCOM) showed that waters with high nutrient and sediment contents in the Fujian and Zhejiang coastal areas in the southern part of the East China Sea could flow into the SCS. The directions and lengths of the fronts were found to be associated with the flow advection.
在一次有利于下降流的风期间，利用 490nm 的漫衰减系数（K(490)），在粤东（EGD）沿海水域检测到了一个沿海锋面。利用 2003 年至 2017 年收集的长期卫星数据、气象数据和水文数据，共同分析了影响沿海锋面的环境因素。发现沿海锋面的强度与下降流强度有关。粤东沿海浅水区（水深小于 25 米）的月平均 K(490)异常与 ERA5 数据集反演的月平均 Ekman 抽吸速度呈负相关，皮尔逊相关系数为-0.71。锋面于 10 月开始，1 月后逐渐减弱并消失，从广东省东南部向南海万山群岛呈西南方向延伸。沿锋面的平均 K(490)值差异可达 3.7 m。在 22.5°N 和 22.2°N 的经向平均 K(490)值分布和 114.7°E 和 114.4°E 的纬向平均 K(490)值分布中均发现了明显的峰值。随着纬度的增加，峰值趋于变窄。从全球混合坐标海洋模型（HYCOM）获得的平均沿海表面流显示，东海南部福建和浙江沿海地区富含营养物质和沉积物的水可以流入南海。锋面的方向和长度与流的平流有关。
