The DSI - a dynamic weather and climate index

The Dynamic State Index (DSI) is a scalar diagnostic field that indicates deviations from a steady, adiabatic and inviscid atmospheric basic state. It is defined as Jacobian determinant of the potential voticity, the Bernoulli stream function and the potential temperature. Several works have been demonstrated that the DSI provides a suitable parameter to indicate diabatic processes across all scales. So far, DSI variants for different atmospheric models have been derived and applied to diagnose e.g. the onset and presence of precipitation or the organization of storms. In a novel approach DSI variants that identify specific polytropic states (isobaric, isochoric, isentropic, isothermal) of the atmosphere can be used for an analysis of cloud processes at different climate zones.