论文标题
热跃层深度富含水的系外行星
Thermocline Depth on Water-rich Exoplanets
论文作者
论文摘要
水丰富的系外星是水丰富的一种陆地行星，其海洋深度可以达到数十亿至数百千米，没有暴露的大陆。由于缺乏裸露的大陆，西部边界当前和沿海上升都不存在，并且向海洋推翻循环成为将沉积在深海中的养分返回热跃层和地表海洋的最重要方法。我们发现，风驱动的循环是通过Ekman泵送和俯冲的覆盖细胞的主导，以及与地球上南极圆形极电流相似的区域（西方）环圆形电流。受风影响的热跃层深度几乎没有对海洋深度的依赖，在大量参数下，热跃层受到海洋上层的限制。受影响影响的热跃层在海洋上10公里内受到限制，即使在极其强烈的垂直混合下，也无法到达海底。地球上热层面深度的缩放理论适用于富含水的系外行星的热跃层深度。但是，由于缺乏裸露的大陆，区域和子午流速度的大小与地球海洋的大小不同，这导致富含水的系外行星的缩放关系与地球上使用的缩放关系有些不同。
Water-rich exoplanet is a type of terrestrial planet that is water-rich and its ocean depth can reach tens of to hundreds of kilo-meters with no exposed continents. Due to the lack of exposed continents, neither western boundary current nor coastal upwelling exists, and ocean overturning circulation becomes the most important way to return the nutrients deposited in deep ocean back to the thermocline and to the surface ocean.Here we investigate the depth of the thermocline in both wind-dominated and mixing-dominated systems on water-rich exoplanets using the global ocean model MITgcm. We find that the wind-driven circulation is dominated by overturning cells through Ekman pumping and subduction and by zonal (west--east) circum-longitudinal currents, similar to the Antarctic Circumpolar Current on Earth. The wind-influenced thermocline depth shows little dependence on the ocean depth, and under a large range of parameters, the thermocline is restricted within the upper layers of the ocean. The mixing-influenced thermocline is limited within the upper 10 km of the ocean and can not reach the bottom of the ocean even under extremely strong vertical mixing. The scaling theories for the thermocline depth on Earth are applicable for the thermocline depth on water-rich exoplanets. However, due to the lack of exposed continents, the zonal and meridional flow speeds are not in the same magnitude as that in the oceans of Earth, which results in the scaling relationships for water-rich exoplanets are a little different from that used on Earth.
