湾流及邻近海区15 m层流场特征分析

Analysis of the Characteristics of 15 m Laminar Current Field of the Gulf Stream and Its Adjacent Sea Areas

基于1979—2017年共38 a的水帆位于15 m层的Argos漂流浮标资料,分析了湾流及邻近海区表层的多年年平均、夏半年和冬半年平均流场特征,主要包括湾流的流动路径、流速变化、支流分布以及邻近海区的涡旋运动等。湾流的流动路径是由若干个弯曲流段与平直流段共同组成的,从佛罗里达海峡至哈特勒斯角的流段路径基本沿着美国东部海岸线,夏半年与冬半年平均的流动路径基本一致,而从哈特勒斯角以东至纽芬兰浅滩的流段路径较为平直,在纽芬兰浅滩附近海域出现多次弯曲过程,该流段在夏半年弯曲较为明显,冬半年相对平直。汇入湾流的支流与流出的分支在夏半年与冬半年的流速存在一定差异;湾流邻近海区的涡旋运动多发生在流动方向的右侧,且冬半年涡旋运动略强于夏半年。湾流的流速分布呈现出平直流段的高流速区段和弯曲流段的低流速区相互交错的状况,且夏半年流速整体强于冬半年。

Based on 38 years of data collected by Argos drifting buoys which sailed at the water depth of 15 m from1979 to 2017,the annually and half-yearly averaged characteristics of the surface current fields of the Gulf Stream and its adjacent sea areas are analyzed,which include the flow path,velocity variations and tributary distributions of the Gulf Stream and the vortex motion in its adjacent sea areas. The flow path of the Gulf Stream is composed of several bending flow segments and flat direct current segments. The path of the flow segment from the Florida Strait to the Cape Hatteras is roughly parallel to the eastern coastline of the United States and keeps basically the same in summer half year and winter half year. The path of the flow segment from the east of Cape Hatteras to the Newfoundland Shoal is relatively flat,with multiple bending processes occurring near the Newfoundland Shoal. This flow segment is more obvious in bending in summer half year and becomes relatively flat in winter half year. Both the tributaries flowing into the Gulf Stream and the branches flowing out of the Gulf Stream are,to some extent,different in flow velocity in summer half year and winter half year. The vortex motion in the adjacent sea areas of the Gulf Stream occurs mostly on the right side of the flow direction and is slightly stronger in winter half year than in summer half year. The distribution of the flow velocity of the Gulf Stream shows that the high velocity sections of the flat direct current segments and the low velocity zones of the bending flow segments are interlaced with each other,and the overall flow velocity in summer half year is stronger than that in winter half year.