Abstract Characterization of the complex dynamics of economic cycles, by identifying regular and irregular patterns and regime switching between different dynamic phases in the economic time series, is the key to improve economic forecasting. Statistical analysis of stock markets and foreign exchange markets have demonstrated the intermittent nature of nonlinear economic time series, which exhibits non-Gaussian behavior in the probability distribution function of price changes and power-law dependence on frequency in the spectral density. Nonlinear deterministic models of economic dynamics are capable of simulating intermittent time series due to a transition from order to chaos, or from weak chaos to strong chaos, which can explain the origin and nature of intermittency observed in economic systems. We discuss the complex systems approach to intermittency based on a forced van der Pol oscillator of business cycles and a model of Alfv\'en chaos in the solar-terrestrial environment. The technique of numerical modeling is applied to characterize the fundamental properties of complex economic and solar-terrestrial systems which 1713 2010 1-
