Behaviour of the centres of action above the Atlantic since 1881. Part I: Characteristics of seasonal and interannual variability

Abstract

Based on generated time series of the central pressure, latitudinal and longitudinal position of the Iceland Low, Azores High, Inter Tropical Convergence Zone and South Atlantic Subtropical High, the behaviour of these atmospheric centres of action since 1881 is examined with regard to the intra- and interannual variations, persistence of anomalies, linear trends and interactions. The critical analysis of these time series as well as those of the pressure gradients between the neighbouring centres suggests that the existing non-periodic fluctuations of the surface atmospheric circulation on the time-scale of one or more decades suppress the long-term changes. These fluctuations are similar to the ‘internal’ variations of the climate system, recognized in the climate simulations of coupled ocean–atmosphere models. © 1998 Royal Meteorological Society.