Tim Palmer

Abstract:

First, an empirical orthogonal function (EOF) analysis is made of outgoing longwave radiation (OLR) in the tropics over seven winters. Having removed the seasonal cycle and interannual variability, the two leading EOFs describe the 30-60 day oscillation. A composite of extratopical 500 mb geopotential height correlated simultaneously with this mode of tropical variability is constructed. The 500 mb height composite is compared succesfully, with the Simmons, Wallace and Branstator (SWB) mode of barotropic instability, which has similar periodicity and similar spatial structure in both its phase-quadrature components. In the final phase of this study, the ECMWF model has been integrated over four wintertime 20-day periods. -from Authors

Abstract:

The implications of the inherent unpredictability of weather patterns, as part of a chaotic system, are discussed. The work of the meteorologist Edward Lorenz and his development of the concept of the Lorenz attractor are used to illustrate the application of chaos dynamics to weather forecasting problems. (D.W.T.)