Climatological structure of the quasi-2-day wave (Q2DW) at middle latitudes in temperature and horizontal winds in the mesosphere and lower thermosphere (MLT) was compared between the northern and southern hemispheres. Determination of the Q2DW in temperature was based on observation data by the Microwave Limb Sounder (MLS) onboard NASA's Earth Observing System (EOS) Aura satellite over 17 years from August 2004 to May 2021 and the Q2DW in horizontal winds was derived from Aura/MLS geopotential height data using balance equations. Amplitudes were maximized in summer in the southern hemisphere and in the meridional wind in the northern hemisphere, but in winter in the zonal wind in the northern hemisphere. Summer amplitudes were larger in the meridional wind than the zonal wind in the southern hemisphere, but zonal amplitudes in winter were larger than meridional amplitudes in summer in the northern hemisphere. Westward propagating zonal wavenumber 3 (W3) was largest in both hemispheres, but in addition to well-known W4, W3, W2 and eastward propagating zonal wavenumber 2 (E2), we also found W1, zonally symmetric standing (S0), and E1. Eliassen-Palm fluxes were derived for each mode. W3, W2, W1, and E2 fluxes were exhibited upward and poleward in January in the southern hemisphere while only W3 fluxes were exhibited clearly upward and poleward in July in the northern hemisphere. The balance winds and radar winds agreed in both amplitude and phase in the southern hemisphere and at lower latitudes in the northern hemisphere in January, and at lower latitudes in both hemispheres in July. Furthermore, the Q2DW is modulation in amplitude and phase from the W3 by accumulating other modes.

比较了北半球和南半球的中纬度准2天波（Q2DW）的气候结构以及中层和低热层（MLT）的水平风。温度中 Q2DW 的确定基于 NASA 地球观测系统 (EOS) Aura 卫星上的微波探臂仪 (MLS) 在 2004 年 8 月至 2021 年 5 月的 17 年间的观测数据，水平风中的 Q2DW 来自 Aura/MLS使用平衡方程的位势高度数据。南半球夏季和北半球的经向风幅度最大，但北半球的冬季纬向风幅度最大。夏季经向风的振幅大于南半球的纬向风，但北半球冬季纬向波幅大于夏季经向波幅。向西传播的纬向波数 3（W3）在两个半球最大，但除了众所周知的 W4、W3、W2 和向东传播的纬向波数 2（E2）外，我们还发现了 W1、纬向对称站立（S0）和 E1 . Eliassen-Palm 通量是针对每种模式得出的。W3、W2、W1 和 E2 通量在南半球 1 月呈现向上和向极的趋势，而在北半球 7 月仅 W3 通量明显向上向极呈现。1 月份南半球和北半球低纬度地区的平衡风和雷达风在振幅和相位上都一致，7 月份在两个半球的低纬度地区风速一致。此外，