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Laboratory for Atmospheric and Space Physics

Stratosphere-troposphere coupling

Investigating the effects of stratospheric processes on tropospheric weather systems is a new area of research in our group. Explorations over the last couple decades have revealed that interactions between the stratosphere and troposphere are significant. The primary mechanism that couples the polar winter troposphere and stratosphere is vertical propagation of planetary waves. When planetary waves that propagate into the winter stratosphere break, the momentum they deposit weakens or even reverses the stratospheric zonal winds. Since planetary waves cannot propagate upward past this modified wind regime, they will break subsequently at lower and lower altitudes. Eventually they will break in the upper troposphere, thereby affecting the polar jet stream. This will influence such phenomena as storm tracks, cold air outbreaks and precipitation. We are studying these processes in order to improve seasonal forecasting and to better assess global climate models.