Early Mars climate research has well-defined goals (MEPAG 2018). Achieving these goals requires geologists and climate modelers to coordinate. Coordination is easier if results are expressed in terms of well-defined parameters. Key parameters include the following quantitative geologic constraints. (1) Cumulative post-3.4 Ga precipitation-sourced water runoff in some places exceeded 1km$1~\mbox{km}$ column. (2) There is no single Early Mars climate problem: the traces of ≥2 river-forming periods are seen. Relative to rivers that formed earlier in Mars history, rivers that formed later in Mars history are found preferentially at lower elevations, and show a stronger dependence on latitude. (3) The duration of the longest individual river-forming climate was >(102–103)yr${>}(10^{2}\mbox{--}10^{3})~\mbox{yr}$, based on paleolake hydrology. (4) Peak runoff production was >0.1mm/hr${>}0.1~\mbox{mm}/\mbox{hr}$. However, (5) peak runoff production was intermittent, sustained (in a given catchment) for only <10% of the duration of river-forming climates. (6) The cumulative number of wet years during the valley-network-forming period was >105yr${>}10^{5}~\mbox{yr}$. (7) Post-Noachian light-toned, layered sedimentary rocks took >107yr${>}10^{7}~\mbox{yr}$ to accumulate. However, (8) an “average” place on Mars saw water for <107yr${<}10^{7}~\mbox{yr}$ after the Noachian, suggesting that the river-forming climates were interspersed with long globally-dry intervals. (9) Geologic proxies for Early Mars atmospheric pressure indicate pressure was not less than 0.012 bar but not much more than 1 bar. A truth table of these geologic constraints versus currently published climate models shows that the late persistence of river-forming climates, combined with the long duration of individual lake-forming climates, is a challenge for most models.

中文翻译：

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早期火星气候的地质限制

早期的火星气候研究有明确的目标（MEPAG 2018）。实现这些目标需要地质学家和气候建模者进行协调。如果结果以明确定义的参数表示，则协调会更容易。关键参数包括以下定量地质约束。(1) 部分地区3.4 Ga后累积降水源水径流超过1km$1~\mbox{km}$列。(2) 不存在单一的早期火星气候问题：可见≥2条河流形成时期的痕迹。相对于火星历史形成较早的河流，火星历史形成较晚的河流优先出现在低海拔地区，对纬度的依赖性更强。(3)单个河流形成气候持续时间最长为>(102-103)yr${>}(10^{2}\mbox{--}10^{3})~\mbox{yr}$ , 基于古湖泊水文学。(4) 径流产量峰值 >0.1mm/hr${>}0.1~\mbox{mm}/\mbox{hr}$。然而，(5) 高峰径流生产是间歇性的，持续的（在给定的流域）只有不到 10% 的河流形成气候持续时间。(6) 谷网形成期累计湿润年数>105yr${>}10^{5}~\mbox{yr}$。(7) 后诺亚纪浅色层状沉积岩需要 >107yr${>}10^{7}~\mbox{yr}$ 积累。然而，（8）火星上一个“平均”的地方在诺亚纪之后看到的水<107yr${<}10^{7}~\mbox{yr}$，这表明形成河流的气候在全球范围内穿插了很长时间——干燥间隔。(9) 早期火星大气压力的地质代数表明压力不低于0.012 bar，但不超过1 bar。