New Approach to Estimate Tidal Climatology From Ground‐ and Space‐Based Observations

This paper proposes a new approach to obtain seasonal variations of global tides for the horizontal winds in the mesosphere and lower thermosphere region, based on daily tides derived from the global coverage of the TIMED Doppler Interferometer (TIDI) and the local‐time coverage of a meteor radar chain. The daily variations of different mesosphere and lower thermosphere tides are obtained taking advantage of empirical tidal mode (ETM), which is first derived from Global Scale Wave Model using empirical orthogonal function analysis. ETM displays latitudinal and vertical features of each tidal component in a realistic background atmosphere with dissipation effects. After fitting the observations by ETM day by day, the monthly mean of daily fitted results is then used to describe tidal monthly features. Seasonal variations of three major tidal components were found: DW1 in both zonal and meridional winds usually has two maxima around equinoxes, DE3 in zonal winds achieves their maximum in September, while that in meridional winds becomes strongest in February and November. SW2 in zonal winds reaches largest amplitudes in May in the southern hemisphere, and meridional winds has minor peaks in February and November in the northern hemisphere. At last, we superpose each tidal component with the same frequency to reconstruct the global diurnal and semidiurnal tidal winds. Comparing them with both of TIDI 60‐day average winds and outputs of Global Scale Wave Model model, similar characteristics and magnitudes indicate their consistency and confirm the reliability and feasibility of this new approach.