Liquid water oceans are at the center of our search for life on exoplanets because water is a strict requirement for life as we know it. However, oceans are dynamic habitats---and some oceans may be better hosts for life than others. In Earth's ocean, circulation transports essential nutrients such as phosphate and is a first-order control on the distribution and productivity of life. Of particular importance is upward flow from the dark depths of the ocean in response to wind-driven divergence in surface layers. This `upwelling' returns essential nutrients that tend to accumulate at depth via sinking of organic particulates back to the sunlit regions where photosynthetic life thrives. Ocean dynamics are likely to impose constraints on the activity and atmospheric expression of photosynthetic life in exo-oceans as well, but we lack an understanding of how ocean dynamics may differ on other planets. We address this issue by exploring the sensitivity of ocean dynamics to a suite of planetary parameters using ROCKE-3D, a fully coupled ocean-atmosphere GCM. Our results suggest that planets that rotate slower and have higher surface pressure than Earth may be the most attractive targets for remote life detection because upwelling is enhanced under these conditions, resulting in greater nutrient supply to the surface biosphere. Seasonal deepening of the mixed layer on high obliquity planets may also enhance nutrient replenishment from depth into the surface mixed layer. Efficient nutrient recycling favors greater biological activity, more biosignature production, and thus more detectable life. More generally, our results demonstrate the importance of considering oceanographic phenomena for exoplanet life detection and motivate future interdisciplinary contributions to the emerging field of exo-oceanography.

中文翻译：

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系外行星生命探测的海洋学考虑

液态水海洋是我们在系外行星上寻找生命的中心，因为水是我们所知的生命的严格要求。然而，海洋是动态的栖息地——有些海洋可能比其他海洋更适合生存。在地球的海洋中，循环运输重要的营养物质，如磷酸盐，是对生命分布和生产力的一级控制。特别重要的是从海洋的黑暗深处向上流动，以响应表层的风驱动发散。这种“上升流”将通过有机颗粒下沉到光合作用生命蓬勃发展的阳光照射区域而倾向于在深处积累的基本营养物质返回。海洋动力学也可能对外洋中光合生命的活动和大气表达施加限制，但我们对海洋动力学在其他星球上的不同之处缺乏了解。我们通过使用 ROCKE-3D（一种完全耦合的海洋-大气 GCM）探索海洋动力学对一系列行星参数的敏感性来解决这个问题。我们的研究结果表明，自转比地球更慢、表面压力更高的行星可能是远程生命探测最有吸引力的目标，因为在这些条件下上升流会增强，从而为地表生物圈提供更多的营养供应。高倾角行星上混合层的季节性加深也可能会增强营养从深处到地表混合层的补充。有效的养分循环有利于更大的生物活性，更多的生物印记产生，从而更容易检测到生命。更普遍，