| Summary: | An extreme (weather and climate) event does not only mean that an extreme occurs at a location, but more generally it can impact a certain area and last a certain period of time, which is defined as a regional extreme event (REE) with a certain impacted area and duration. The concept of REE has been defined to allow mainly objective assessment of the events without a pre-determined boundary and duration. This paper reviews the studies on REEs published during the past 20 years, especially recent years. Mainly in view of methodology, these studies can be divided into three types: studies focusing on spatial simultaneity, studies focusing on temporal persistence, and studies identifying REEs. The methods identifying REEs include two kinds, e.g., type-I methods stressing REE's temporal persistence within a relatively certain area and type-II methods focusing on catching a complete REE. Identification methods proposed in this paper could provide valuable information for various purposes, such as real-time monitoring, estimating long-term changes, mechanism diagnosis, forecasting study and even attribution analysis. Research on REEs is important for objectively defining extreme weather and climate events, which depends on the spatial and temporal scales of interest. Such an objective definition will support ongoing climate monitoring and improve the assessment of how regional extreme events have changed over time. Keywords: Extreme (weather and climate) events, Regional extreme events, Research progress, Review
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