CEDAR Postdoc: Seasonal Variations in Mesopause Region Temperatures, Zonal and Meridional Winds: Climatology and Variability of Mean-State, Diurnal and Semidiurnal Tides

本文研究中层顶区温度和纬向风的季节变化。科罗拉多州的钠激光雷达已经升级为双光束系统，能够在天气允许的情况下，在整个昼夜周期内同时测量中层顶区域的温度和风。2002年5月开始以这种方式进行定期观测，到2003年4月底，完成了整整一年的数据采集工作，总共观测了1，388小时，其中634小时是在阳光条件下观测的。具有全昼夜周期覆盖的数据集的显着特征在于其能够将动力场（温度，纬向风和纬向风）的垂直剖面分解为具有不同潮汐周期的日平均值和振荡的唯一线性叠加，加上残差。这样，潮汐周期振荡的日平均值、振幅和相位就可以完全由实验数据确定。潮汐激发和平均太阳强迫的一致性战胜了变异性，导致了多日观测中气候平均值的收敛。6天的综合收益率的平均值和昼夜潮汐模型预测非常相似。对其他月份所获得的资料的初步分析，大致显示出与气候平均值相似的变率和一致的收敛，尽管每个月的表现取决于是否有完整的昼夜循环资料和非典型廓线的出现频率。虽然第一年的观测结果超出了预期，但按照目前的速度，需要三年的数据采集才能对气候学和变异性进行可靠的研究。本研究将继续作为博士后项目的观察和相关科学研究。

This is a study of seasonal variations of temperatures and meridional winds in the mesopause region. The Colorado State sodium lidar has been upgraded to a two-beam system capable of simultaneous measurements of mesopause region temperature and winds, over full diurnal cycles, weather permitting. Regular observations in this mode of operation began in May 2002, and by the end of April 2003, one full year of data acquisition was completed giving a total of 1,388 hours of observation with 634 hours under sunlit conditions. The salient feature of a dataset with full-diurnal-cycle coverage lies in its ability to decompose the vertical profiles of dynamical fields (temperature, zonal and meridional winds) into a unique linear superposition of diurnal-mean and oscillations with different tidal periods, plus a residual. In this manner, the diurnal-mean and the amplitude and phase of tidal period oscillations can be determined solely from experimental data. The coherence of tidal excitation and of mean solar forcing prevails over the variability, leading to the convergence of the climatological mean in a multi-day observation. The 6-day composite yields means and diurnal tides that resemble model predictions very well. Preliminary analyses on data acquired in other months have generally shown similar variability and coherent convergence to climatological means, though the behavior in each month depends on the availability of full-diurnal-cycle data and the occurrence frequency of atypical profiles. Though the results of the first year of observation have exceeded expectations, at the present rate, it would require three years of data acquisition to produce a reliable study of climatology and variability. This study will continue the observations and associated science study as a post-doctoral program.