Response of quasi-10-day waves in the MLT region to the sudden stratospheric warming in March 2020

We present an analysis of the response of quasi-10-day waves (Q10DWs) to the sudden stratospheric warming (SSW) event which occurred on March 23, 2020. The Q10DWs are observed in the mesosphere and lower thermosphere (MLT) region by three meteor radars, which are located at middle latitudes along the 120°E meridian from Mohe (MH, 53.5°N, 122.3°E), Beijing (BJ, 40.3°N, 116.2°E), to Wuhan (WH, 30.5°N, 114.6°E). The Q10DWs reveal similar temporal and altitudinal variations during the SSW in the MLT region at the three stations. The activities of Q10DWs are also captured in the temperature measurements from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) on the Thermosphere Ionosphere Mesosphere Energetics and Dynamics satellite in the MLT region. Further analysis of the Q10DW phases indicates that the Q10DWs might be in situ generated due to mesospheric instabilities at higher latitudes around MH and then propagate southward to lower latitudes at BJ and WH. The atmospheric instabilities are not directly responsible for the excitations of Q10DWs at lower latitudes, while the observed equatorward propagation of the Q10DWs is important. Our result provides the observational evidence for latitudinal couplings in the MLT region after the SSW onset, which is achieved by southward propagating planetary waves in the MLT region.     

基于模态发生器的进气道风扇噪声及声衬降噪实验

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基于离子污染度数据分析的航空电子产品水清洗质量提升技术

本文应用ROSE/SEC法测试航空电子产品印制板组件(PCBA)的离子污染度,以测试结果反映水清洗效果,通过工序能力指数Cpk对工艺参数进行评价,同时运用统计过程控制(SPC)对清洗工序进行监控,实现对航空电子产品水清洗工艺清洗质量的提升.试验结果表明,降低PCBA相互遮挡面积可有效降低离子污染度.结合Xbar-S控制...