标题： 大气质量高的夜间过渡到温带气候 显示英文标题

标题： Climate Transition to Temperate Nightside at High Atmosphere Mass

摘要： 我们的近期研究表明，M-Earth（类地行星）的气候和传输光谱如何依赖于行星白昼侧无冰海洋的比例以及大气中N2的质量。 拥有更多无冰海洋和更厚大气层的M-Earth行星更热、更潮湿，并且在它们的传输光谱中具有更大的水蒸气特征。 在这篇文章中，我们描述了高pN2模拟中的一个气候转变，从传统的“独眼龙”M-Earth气候（其中仅子午点区域是温带的），过渡到“温带夜侧”状态（在这种状态下，白昼侧和夜晚侧都完全无冰）。 在这两种状态之间，存在一个“过渡”状态，部分夜晚侧覆盖着冰。 我们使用三维气候模拟来描述从冻结到非冰冻的夜晚侧气候转变。 我们将这种转变归因于较厚大气层中水蒸气增加的平流和热量输送。 我们发现，当恒星辐射通量或pCO2被扰动时，夜晚侧在冻结和无冰之间平滑地来回转换，没有滞后现象。 我们也发现在较冷行星上存在类似的转变：那些具有薄大气层的行星在低恒星辐射通量时可以有一个白昼热点，而那些具有更高质量大气层的行星由于热量从子午点向远处的更大平流作用，更有可能处于“雪球”状态，即白昼侧完全冻结。 我们展示了这两种气候转变如何对恒星辐射通量、陆地覆盖和大气质量敏感。 我们为模拟中的各种气候生成合成的传输光谱和相位曲线。 显示英文摘要

摘要： Our recent work shows how M-Earth climates and transmission spectra depend on the amount of ice-free ocean on the planet's dayside and the mass of N2 in its atmosphere. M-Earths with more ice-free ocean and thicker atmospheres are hotter and more humid, and have larger water vapour features in their transmission spectra. In this paper, we describe a climate transition in high-pN2 simulations from the traditional ``eyeball" M-Earth climate, in which only the substellar region is temperate, to a ``temperate nightside" regime in which both the dayside and the nightside are entirely ice-free. Between these two states, there is a ``transition" regime with partial nightside ice cover. We use 3D climate simulations to describe the climate transition from frozen to deglaciated nightsides. We attribute this transition to increased advection and heat transport by water vapour in thicker atmospheres. We find that the nightside transitions smoothly back and forth between frozen and ice-free when the instellation or pCO2 is perturbed, with no hysteresis. We also find an analogous transition in colder planets: those with thin atmospheres can have a dayside hotspot when the instellation is low, whereas those with more massive atmospheres are more likely to be in the ``snowball" regime, featuring a completely frozen dayside, due to the increased advection of heat away from the substellar point. We show how both of these climate transitions are sensitive to instellation, land cover, and atmosphere mass. We generate synthetic transmission spectra and phase curves for the range of climates in our simulations.