Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 12 4 2005 10.5194/npg-12-451-2005 http://www.nonlin-processes-geophys.net/12/451/2005/ http://www.nonlin-processes-geophys.net/12/451/2005/npg-12-451-2005.html http://www.nonlin-processes-geophys.net/12/451/2005/npg-12-451-2005.pdf 451 460 2005-04-21 Continuous partial trends and low-frequency oscillations of time series A. R. Tomé P. M. A. Miranda Universidade da Beira Interior, Department of Physics, and Centro de Geofísica da Universidade de Lisboa, Portugal University of Lisbon, Faculdade de Ciências, Centro de Geofísica, Portugal This paper presents a recent methodology developed for the analysis of the slow evolution of geophysical time series. The method is based on least-squares fitting of continuous line segments to the data, subject to flexible conditions, and is able to objectively locate the times of significant change in the series tendencies. The time distribution of these breakpoints may be an important set of parameters for the analysis of the long term evolution of some geophysical data, simplifying the intercomparison between datasets and offering a new way for the analysis of time varying spatially distributed data. Several application examples, using data that is important in the context of global warming studies, are presented and briefly discussed.