BEHAVIOR OF THE CENTERS OF ACTION ABOVE THE ATLANTIC SINCE 1881 - PART-I - CHARACTERISTICS OF SEASONAL AND INTERANNUAL VARIABILITY

Based on generated time series of the central pressure, latitudinal an d longitudinal position of the Iceland Low, Azores High, Inter Tropica l Convergence Zone and South Atlantic Subtropical High, the behaviour of these atmospheric centres of action since 1881 is examined with reg ard to the intra-and interannual variations, persistence of anomalies, linear trends and interactions. The critical analysis of these time s eries as well as those of the pressure gradients between the neighbour ing centres suggests that the existing non-periodic fluctuations of th e surface atmospheric circulation on the time-scale of one or more dec ades suppress the long-term changes. These fluctuations are similar to the 'internal' variations of the climate system, recognized in the cl imate simulations of coupled ocean-atmosphere models. (C) 1998 Royal M eteorological Society.