Iceberg Melt-Driven Convection Inferred from Field Measurements of Temperature
Iceberg Melt-Driven Convection Inferred from Field Measurements of Temperature
复制标题
从现场温度测量推断冰山融化驱动的对流
作者：
E. Josberger;S. Neshyba
在100米深的水中对一座冰山进行的一次性深海温度计（XBT）调查表明，冰山融化驱动的对流以两种方式显著改变了周围的水的性质，一种是在上部40米处的水冷却多达3度，另一种是在密度跃层中形成垂直长度为5米的等温层。这两种影响随着与冰山距离的减小而变得更加明显。上层的整体冷却支持了Neshyba（1977）和Josberger和Martin（准备中 *）的上升流概念，而台阶状结构的形成支持了Huppert和Turner（1978）和Huppert和Josberger（1980）的单元形成理论。冰山周围的天气表面调查显示，存在含有温度低于邻近水的水的融化羽流，这些羽流在0.5公里的距离内都可以检测到。将浓缩的罗丹明置于14和18 m深度处，靠近以30°角向下倾斜的冰墙，沿着冰向上流动。染料分别在240 s和540 s内到达紧邻冰的表面，得到约0.07 m s-1的特征向上速度。然后，染料从冰山向外扩散，直到不再可见。
An expendable bathythermograph (XBT) survey around an iceberg grounded in 100 m of water shows that iceberg melt-driven convection significantly alters the surrounding water properties in two ways, by a general cooling of the water in the upper 40 m by as much as 3 deg and by the formation of isothermal layers with a 5 m vertical-length scale in the pycnocline. Both of these effects become more pronounced as the distance to the iceberg decreases. The overall cooling of the upper layers supports the upwelling concept of Neshyba (1977) and of Josberger and Martin (in preparation*), while the formation of a step-like structure supports the cell formation idea of Huppert and Turner (1978) and Huppert and Josberger (1980). Synoptic surface surveys around the iceberg show the existence of melt plumes containing water of a lower temperature than the adjacent water, and these plumes are detectable at distances of 0.5 km. Concentrated rhodamine placed at depths of 14 and 18 m adjacent to an ice wall sloping down-ward at a 30° angle flowed upward along the ice. The dye reached the surface immediately next to the ice in 240 s and 540 s, respectively, to give a characteristic upward velocity of approximately 0.07 m s−1. The dye then dispersed outward away from the iceberg until it was no longer visible.