Abstract:
Climate is an observable statistical state of the earth—atmosphere system. Climate is ever-changing on all scales of time. Climate element is a hydrodynamic variable (velocity, vorticity) and also a thermodynamic variable (radiation, temperature, etc.). The World Climate Conference (WMO, 1979) defined climate as the synthesis of weather events over the whole of a period statistically long enough to establish its statistical ensemble properties (mean values, variances, probabilities of extreme events, etc.) and is largely independent of any instantaneous state. Climate variability has two components: natural and forced. Natural (internal) variability arises as a result of the instabilities of the nonlinear system, and forced (external) variability arises due to the forcing from the slowly varying changes in the external parameters of the system.
