Assimilation of thermal emission spectrometer atmospheric data during the Mars Global Surveyor aerobraking period
Assimilation of thermal emission spectrometer atmospheric data during the Mars Global Surveyor aerobraking period
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DOI：
10.1016/j.icarus.2007.08.009
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发表时间：
2007-12
期刊：
影响因子：
3.2
通讯作者：
S. Lewis;P. Read;B. Conrath;J. Pearl;Michael D. Smith
中科院分区：
文献类型：
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作者：
S. Lewis;P. Read;B. Conrath;J. Pearl;Michael D. Smith
火星全球勘测者航天器上的热发射光谱仪产生了大量的大气数据集，从空气制动开始，一直持续到整个扩展的科学测绘阶段。在最低点观测模式下，可以从红外光谱中检索出40公里以下大气层的温度分布、表面温度以及总的尘埃和水冰不透明度。本文描述了将航天器大气制动期间（LS=190°-260°，北方秋至冬）的最低点反演资料同化到火星大气环流模式中。同化计划是能够结合联合收割机的信息，从温度和尘埃光学深度检索，利用模型预测包含信息的同化早期观测，以获得全球性的，随时间变化的分析。考虑到足够的温度反演，同化过程表明，即使在缺乏尘埃观测的先验尘埃分布假设的错误，在这种情况下，有相对寒冷的地区相比，假设水平均匀的尘埃分布的模型在两极。使用同化技术的一个主要原因是为了研究火星上的瞬态波行为。虽然2小时航天器测绘轨道阶段的数据更适合同化，但即使是较长（45-24小时）周期的空气制动轨道数据也包含有关三维天气尺度火星环流的有用信息，同化程序可以以一致的方式重建这些信息。从诺奇区域沙尘暴期间的同化表明，温度和沙尘反演的联合同化的大气分析有一个有益的影响。
The Thermal Emission Spectrometer aboard the Mars Global Surveyor spacecraft has produced an extensive atmospheric data set, beginning during aerobraking and continuing throughout the extended scientific mapping phase. Temperature profiles for the atmosphere below about 40 km, surface temperatures and total dust and water ice opacities, can be retrieved from infrared spectra in nadir viewing mode. This paper describes assimilation of nadir retrievals from the spacecraft aerobraking period, LS=190°–260°, northern hemisphere autumn to winter, into a Mars general circulation model. The assimilation scheme is able to combine information from temperature and dust optical depth retrievals, making use of a model forecast containing information from the assimilation of earlier observations, to obtain a global, time-dependent analysis. Given sufficient temperature retrievals, the assimilation procedure indicates errors in the a priori dust distribution assumptions even when lacking dust observations; in this case there are relatively cold regions above the poles compared to a model which assumes a horizontally-uniform dust distribution. One major reason for using assimilation techniques is in order to investigate the transient wave behavior on Mars. Whilst the data from the 2-h spacecraft mapping orbit phase is much more suitable for assimilation, even the longer (45–24 h) period aerobraking orbit data contain useful information about the three-dimensional synoptic-scale martian circulation which the assimilation procedure can reconstruct in a consistent way. Assimilations from the period of the Noachis regional dust storm demonstrate that the combined assimilation of temperature and dust retrievals has a beneficial impact on the atmospheric analysis.