Stratospheric forcing needed for dynamical seasonal prediction

While tropical sea surface temperatures certainly influence the atmosphere; winter circulation, temperature, and precipitation over Northen Hemisphere continents are also influenced by circulation patterns related to the stra tosphere. In particular, large tropical volcanic eruptions produce winter w arming patterns over Northern Hemisphere continents because of a dynamical effect forced by gradients of radiative heating from sulfate aerosols in th e lower stratosphere. These effects must be included for accurate dynamical seasonal predictions of Northern Hemisphere winter temperature over both N orth America and Eurasia.