Evidence of geostrophic motion in the equatorial stratosphere

摘要

AbstractThe characteristics of the temperature oscillation associated with the recently discovered 26‐month oscillation of the zonal wind component in the equatorial stratosphere are inferred from the thermal wind relationship. Computations based on actual wind data predict an amplitude of 2·5°C for the temperature oscillation near the equator and a phase difference of one to two months between wind and temperature cycles at 20 km increasing to seven months at 24 km. The close correspondence between predicted and observed characteristics supports the hypothesis that the 26‐month oscillation is in geostrophic equilibrium.The hypothesis is also supported by a consideration of relative sizes of the local wind acceleration and Coriolis force which indicates that the acceleration becomes an order of magnitude less than the Coriolis force at a distance of 40 km from the eq