We present dayside electron temperature (T_e) and density altitude profiles at Mars from MAVEN satellite deep-dip orbits. The data are after recalibration of the Langmuir Probe and Waves instrument that results in reduced uncertainties to as low as ±82°K. At MAVEN's lowest altitudes, (∼120–∼135 km), the measured values of T_e are, after uncertainties, higher than those predicted by several modeling efforts. To better understand this discrepancy, we perform a basic heat-transfer analysis for two specific dayside deep dips. The analysis supports that CO₂ excitation/de-excitation of its lowest-energy vibrational states dominates energy transfer to and from electrons. We hypothesize that the discrepancy between the measured and modeled T_e is due to (a) the coupling of T_e to CO₂ vibrational temperatures combined with a non-LTE (local thermal equilibrium) excess of excited CO₂ and/or (b) a non-Maxwellian electron distribution that moderates CO₂ cooling.

中文翻译：

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火星白天电离层电子温度和密度的原位测量

我们展示了来自 MAVEN 卫星深倾轨道的火星日侧电子温度 ( T _e ) 和密度高度剖面。数据是在 Langmuir Probe and Waves 仪器重新校准后得出的，该仪器将不确定性降低到 ±82°K。在 MAVEN 的最低高度（~120-~135 公里），在不确定性之后，T _e的测量值高于多个建模工作预测的值。为了更好地理解这种差异，我们对两个特定的日侧深倾角进行了基本的传热分析。该分析支持 CO ₂其最低能量振动状态的激发/去激发支配着与电子之间的能量转移。我们假设测量值和建模值之间的差异T _e是由于 (a) T _e与 CO ₂振动温度的耦合以及非 LTE（局部热平衡）过量激发的 CO ₂和/或 (b) 缓和 CO ₂的非麦克斯韦电子分布冷却。