Intraseasonal and interannual variations of the stratosphere-troposphere coupled system

We have performed numerical experiments with an idealized global circulation model to investigate the internal variability of the stratosphere-troposphere coupled system (Taguchi, Yamaga and Yoden, 2001; Taguchi and Yoden, 2002a,b,c) and the effects of equatorial QBO on such variability (Naito, Taguchi and Yoden, 2003; Naito and Yoden, 2005). These were largely influenced by some of Jim's pioneering works on stratospheric variations such as Holton and Mass (1976) and Holton and Tan (1980, 1982). Our recent study on the interannual variations and trend (Nishizawa and Yoden, 2005) is based on large ensemble experiments with the same model, in which many trials of computations are done by sweeping the value of a control parameter or an initial condition (Yoden, Taguchi and Naito, 2002). These studies with a hierarchy of numerical models are summarized and statistical tests with large ensembles are argued.