中纬度冬季低热层潮汐水平风分量相位关系的MF雷达观测

采用武汉(30°N,114°E)MF雷达在2001年冬季的风场观测数据研究中纬度低热层大气潮汐水平风分量之间的相位关系.统一用弧度定义的各潮汐经纬向分量的拟合初相位在三个连续的高度上分别显示出相同的时间变化倾向和相近的相位差,但是在绝大多数观测时间△ψ24和△ψ12准正交,而△ψ8出乎意料地准同相.周日、半日和8 h潮汐经纬向分量的二次相位耦合(QPC)方程被分别估计出来,利用它们相减还得到一个潮汐相位差相关方程.推测的8 h潮汐相位和相位差与相应的观测值很好地符合.在第14个时间窗内,三个潮汐一般表现为椭圆偏振而不是圆偏振或线偏振,但是△ψ24和△ψ12在三个连续的高度上准正交,而△ψ8在92.0和94.0 km上准同相.因此估计的潮汐QPC方程、推导的潮汐相位差相关方程、观测的8 h潮汐准同相相位差以及典型的潮汐偏振图都是观测的周日、半日和8 h潮汐之间真实QPC的反映. 

MF Radar Observations of Phase Relationships Between Tidal Horizontal Wind Components in the Mid-latitude Winter Lower Thermosphere

Wind measurements obtained from Wuhan/China MF radar during winter 2001 are used to study the phase relationships between tidal horizontal winds in lower thermosphere. The tidal initial phases in any time window are uniformly defined in radians. The meridional and zonal initial phases of each tide exhibit a similar time variation trend at each height and this induces a near phase difference at three consecutive heights. However, in most of the 14 days, △φ4 and △φ12 are quasi-quadrature while △φ8 is unexpectedly quasi-in-phase. The appropriate tidal meridional and zonal quadratic phase coupling （QPC） equations are estimated respectively. The supposed terdiurnal phases and those observed agree well. By subtracting the estimated tidal zonal QPC equation from the meridional, a tidal phase difference correlated equation is obtained. The supposed terdiurnal phase differences and those observed again agree with each other. Within the 14th time window, all the three tides are generally elliptically rather than circularly or linearly polarized. However, both △φ24 and △φ12 in this window are quasi-quadrature at all heights while △φ8 are quasi-in-phase at 92.0 and 94.0km. So the estimated tidal QPC equations, the deduced tidal phase difference correlated equation, the observed terdiurnal quasi-in-phase phase differences and the typical tidal polarization plots are all indications of real QPC between the observed 24, 12 and 8 h tides.