Chapter 4 A short excursion to meteorology: tides in the atmosphere

摘要

The physical phenomena providing impetus to the effects considered in this thesis are atmospheric tides, which refer to global-scale oscillations in the atmosphere at periods that divide evenly into a solar or lunar day (Lindzen,1979). The primary and by far the largest tides are found at diurnal and semi-diurnal frequencies, corresponding to one and two cycles per solar day. While most of the early interest in these phenomena has been attached to the small but regular variations of air pressure at the Earth's surface, the modern understanding of atmospheric tides encompasses temperature, wind,pressure,and even geomagnetic oscillations from the troposphere up to the thermosphere and ionosphere,see e.g. Pancheva et al. (2012). In the first place,this chapter strives to give a general overview of the physics and characteristics of solar tides in the atmosphere. The second part portrays the ensemble of models and datasets from which atmospheric angular momentum and torques at tidal frequencies are deduced.