Dynamical systems persistence parameter of sea surface temperature and its associations with regional averaged index over the tropical Pacific

Due to an index defined from regionally averaged sea surface temperature anomalies (SSTAs) unable to adequately characterize SSTA events, the dynamical persistence parameter θ was employed to infer more information than what the averaged SSTA index (SI) can capture from a new respect. By taking the whole SSTA field over a specific region as a dynamical system, θ was calculated to infer more (such as SSTA gradient) than SI. Moreover, the values of θ can provide the persistence information, low for long‐lasting SSTA events with well‐defined spatial patterns and high for transient behaviours. Globally, θ and SI can be taken as approximately orthogonal, but locally there are distinct associations between them. Detailed studies found that there are three kinds of origins for this global independence: alternating strong negative and positive correlation during extreme events, independence under the neutral conditions and low correlation caused by the inability of SI to the marked SSTA gradient. All above findings improve the understanding on the physical indications of θ and indicate that the new metric θ is at least a good supplement to the SSTA indices based on the regional average. Dynamical persistence parameter θ was employed to infer more than what the averaged SSTA index (SI) can capture. Globally, θ and SI can be taken as approximately orthogonal, but locally they are strongly correlated. New metric θ is at least a good supplement to the regional averaged SSTA indices. In the figure, scatter plot between dynamical persistence parameter θ and normalized SSTA index SI calculated from daily SSTA over Niño3.4 region (5°N–5°S, 170°–120°W). Here black empty circles denote SSTA events for low dynamical persistence parameter θ(0.15