早期火星的气候模拟与估计的降水、径流和侵蚀率
Climate simulations of early Mars with estimated precipitation, runoff, and erosion rates
摘要：
关于火星早期气候的争论是行星科学中最有趣的争论之一。虽然地质证据通常支持更温暖和更潮湿的气候，但气候模型很难模拟这种情况，导致一些人认为火星表面观察到的河流地质（例如山谷网络，修改景观）可能是在寒冷的气候中形成的。然而，正如我们最初使用单柱辐射-对流气候模型[Ramirez et al. 2014 a]预测的那样，早期火山活跃的火星上CO2-H2碰撞诱导吸收（CIA）导致的变暖可能使平均地面温度升高到冰点以上，后来的计算表明，这是可以实现的，氢浓度低至~ 1%。然而，这些预测应该用更复杂的模型来检验。在这里，我们使用一个先进的能量平衡模型，其中包括北部低地海洋表明，平均地面温度接近或略高于水的冰点是必要的雕刻山谷网络。我们的设想与已经提出的相对较大的海洋相一致。在随后的移除过程之前，山谷网络分布将是全球性的。在较低的平均地面温度和较小的海洋规模，降水和表面侵蚀效率减少。温暖期可能在1000万年以下，这可能表明不需要情景性变暖机制。一旦表面冰层覆盖超过CIA假设的阈值，大气崩溃和永久冰川条件就会发生。我们的研究结果支持早期温暖和半干旱气候与许多地质观测相一致。
英文摘要：
The debate over the early Martian climate is among the most intriguing in planetary science. Although the geologic evidence generally supports a warmer and wetter climate, climate models have had difficulty simulating such a scenario, leading some to suggest that the observed fluvial geology (e.g. valley networks, modified landscapes) on the Martian surface, could have formed in a cold climate instead. However, as we have originally predicted using a single-column radiative-convective climate model [Ramirez et al. 2014a], warming from CO2-H2 collision-induced absorption (CIA) on a volcanically active early Mars could have raised mean surface temperatures above the freezing point, with later calculations showing that this is achievable with hydrogen concentrations as low as ~1%. Nevertheless, these predictions should be tested against more complex models. Here, we use an advanced energy balance model that includes a northern lowlands ocean to show that mean surface temperatures near or slightly above the freezing point of water were necessary to carve the valley networks. Our scenario is consistent with a relatively large ocean as has been suggested. Valley network distributions would have been global prior to subsequent removal processes. At lower mean surface temperatures and smaller ocean sizes, precipitation and surface erosion efficiency diminish. The warm period may have been ~< 10 million years, perhaps suggesting that episodic warming mechanisms were not needed. Atmospheric collapse and permanently glaciated conditions occur once surface ice coverage exceeds a threshold depending on CIA assumptions. Our results support an early warm and semi-arid climate consistent with many geologic observations.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
