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首页> 外文期刊>Journal of geophysical research. Planets >Mars atmospheric CO_2 condensation above the north and south poles as revealed by radio occultation, climate sounder, and laser ranging observations
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Mars atmospheric CO_2 condensation above the north and south poles as revealed by radio occultation, climate sounder, and laser ranging observations

机译：通过无线电掩星，气候探测仪和激光测距观测发现，火星在北极和南极上方的大气CO_2凝结

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We study the condensation of CO_2 in Mars’ atmosphere using temperature profiles retrieved from radio occultation measurements from Mars Global Surveyor (MGS) as well as the climate sounding instrument onboard the Mars Reconnaissance Orbiter (MRO), and detection of reflective clouds by the MGS Mars Orbiter Laser Altimeter (MOLA). We find 11 events in 1999 where MGS temperature profiles indicate CO_2 condensation and MOLA simultaneously detects reflective clouds. We thus provide causal evidence that MOLA non-ground returns are associated with CO_2 condensation, which strongly indicates their nature being CO_2 clouds. The MGS and MRO temperature profiles together reveal the seasonal expansion and shrinking of the area and the vertical extent of atmospheric saturation. The occurrence rate of atmospheric saturation is maximized at high latitudes in the middle of winter. The atmospheric saturation in the northern polar region exhibits more intense seasonal variation than in the southern polar region. In particular, a shrinking of saturation area and thickness from L_S ~ 270° to ~300° in 2007 is found; this is probably related to a planet-encircling dust storm. Furthermore, we integrate the condensation area and the condensation occurrence rate to estimate cumulative masses of CO_2 condensates deposited onto the northern and southern seasonal polar caps. The precipitation flux is approximated by the particle settling flux which is estimated using the impulse responses of MOLA filter channels. With our approach, the total atmospheric condensation mass can be estimated from these observational data sets with average particle size as the only free parameter. By comparison with the seasonal polar cap masses inferred from the time-varying gravity of Mars, our estimates indicate that the average condensate particle radius is 8–22 mm in the northern hemisphere and 4–13 mm in the southern hemisphere. Our multi-instrument data analysis provides new constraints on modeling the global climate of Mars.
机译：我们使用从火星全球测量师（MGS）的无线电掩星测量结果以及火星侦察轨道飞行器（MRO）上的气候探测仪器中获取的温度分布图，以及MGS火星探测到的反射云，研究了火星大气中CO_2的凝结轨道激光高度计（MOLA）。我们在1999年发现了11个事件，其中MGS温度曲线表明CO_2凝结，而MOLA同时检测到反射云。因此，我们提供了MOLA非地面收益与CO_2凝结有关的因果证据，这有力地表明了其性质为CO_2云。 MGS和MRO的温度曲线共同揭示了该区域的季节性膨胀和收缩以及大气饱和度的垂直范围。在冬季中期，高纬度地区的大气饱和发生率最大。与南极地区相比，北极地区的大气饱和度表现出更大的季节变化。特别是，2007年饱和区域和厚度从L_S〜270°缩小到〜300°;这可能与环绕行星的沙尘暴有关。此外，我们对凝结面积和凝结发生率进行积分，以估算沉积在北部和南部季节性极地盖上的CO_2凝结物的累积质量。沉淀通量由颗粒沉降通量估算，该颗粒沉降通量是使用MOLA过滤器通道的脉冲响应估算的。使用我们的方法，可以从这些观测数据集中估算总大气凝结质量，而平均粒径是唯一的自由参数。与从火星随时间变化的重力推断出的季节性极帽总质量相比，我们的估计表明，北半球的平均凝结物半径为8–22 mm，南半球的平均凝结物半径为4–13 mm。我们的多仪器数据分析为建模火星的全球气候提供了新的限制。

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