Climatology of the stratosphere and mesosphere

Abstract The use of all available radiosonde, rocketsonde and satellite data, has elucidated the climatology of the atmosphere up to the mesopause. The seasonal variation of the temperature in the stratosphere and mesosphere will be described, mainly from monthly mean maps. Emphasis will be given to longitudinal and hemispheric differences. During the winter season when, owing to the development of the cold stratospheric polar vortex, the winds in the stratosphere are mainly from the west, the planetary waves of the troposphere penetrate into the stratosphere, and even into the mesosphere during the northern winter. This results in longitudinal differences over both hemispheres, though the effect is stronger over the Northern Hemisphere. The hemispheric differences are particularly large between the winters, as the stratospheric midwinter warmings are different over both hemispheres. As a consequence, the transition from the winter to the sum m er circulation also evolves differently. During summer, the southern stratosphere is warmer than the northern because of the difference in solar heating of ozone due to the ellipticity of the Earth ’s orbit.