We study the interannual variability of atmospheric gravity waves (GWs) in the Martian thermosphere and their relation to the background temperatures using Ar densities measured by Neutral Gas and Ion Mass Spectrometer/Mars Atmosphere and Volatile Evolution (MAVEN). The amplitudes and wavelengths of the GWs are extracted from the neutral density perturbations in the inbound segment of the MAVEN orbit. The GW amplitudes predominantly lie between 5% and 10% and are mostly less than 30% of the background densities. The horizontal wavelengths are between 50 km and 300 km with peak wavelengths of 100–130 km. GW amplitudes show a significant diurnal variation with larger amplitudes during nighttime and smaller amplitudes during daytime. In addition, the GW amplitudes negatively correlate with the background temperatures indicating the role of convective instability in the saturation of the GWs. Most importantly, the GW amplitudes are larger and the wavelengths are smaller when there was a planet‐encircling dust event in the Mars’ lower atmosphere during 2018. As a result, the typical diurnal variation of GW amplitudes is not apparent. During the lower atmospheric dust event, the GW amplitudes do not show any significant correlation with the background temperatures. It is proposed that the PEDE‐2018 led to changes in the circulation of the mesosphere and lower thermosphere, so that the modified circulation enhanced the upward propagation/reduced the filtering of GWs leading to their enhancement in the upper thermosphere.

中文翻译：

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火星热圈中大气重力波的年际变化：2018年环绕地球的尘埃事件的影响

我们使用中性气体和离子质谱仪/火星大气和挥发性演化（MAVEN）测量的Ar密度研究火星热圈中大气重力波（GWs）的年际变化及其与背景温度的关系。GW的振幅和波长是从MAVEN轨道入站区段的中性密度扰动中提取的。GW振幅主要在5％和10％之间，并且大多数小于背景密度的30％。水平波长在50 km至300 km之间，峰值波长在100–130 km之间。GW振幅显示出明显的昼夜变化，夜间振幅较大，而白天则较小。此外，GW振幅与背景温度负相关，表明对流不稳定性在GWs饱和中的作用。最重要的是，在2018年火星低空发生环绕行星的尘埃事件时，GW振幅较大且波长较小。因此，GW振幅的典型昼夜变化并不明显。在较低的大气尘埃事件期间，GW振幅与背景温度没有显示任何显着相关性。有人提出，PEDE-2018导致中层和下热圈的循环发生变化，因此改良的循环增强了GW的向上传播/减少了GW的过滤，从而导致它们在上热圈的增强。当2018年火星低空发生环绕行星的尘埃事件时，GW振幅较大，而波长更小。因此，GW振幅的典型昼夜变化并不明显。在较低的大气尘埃事件期间，GW振幅与背景温度没有显示任何显着相关性。有人提出，PEDE-2018导致中层和下热圈的循环发生变化，因此改良的循环增强了GW的向上传播/减少了GW的过滤，从而导致它们在上热圈的增强。当2018年火星低空发生环绕行星的尘埃事件时，GW振幅较大，而波长更小。因此，GW振幅的典型昼夜变化并不明显。在较低的大气尘埃事件期间，GW振幅与背景温度没有显示任何显着相关性。有人提出，PEDE-2018导致中层和下热圈的循环发生变化，因此改良的循环增强了GW的向上传播/减少了GW的过滤，从而导致它们在上热圈的增强。在较低的大气尘埃事件期间，GW振幅与背景温度没有显示任何显着相关性。有人提出，PEDE-2018导致中层和下热圈的循环发生变化，因此改良的循环增强了GW的向上传播/减少了GW的过滤，从而导致它们在上热圈的增强。在较低的大气尘埃事件期间，GW振幅与背景温度没有显示任何显着相关性。有人提出，PEDE-2018导致中层和下热圈的循环发生变化，因此改良的循环增强了GW的向上传播/减少了GW的过滤，从而导致它们在上热圈的增强。