Spatiotemporal Characteristics and Propagation of Summer Extreme Precipitation Events over USA: A Complex Network Analysis

Abstract:

A concise understanding of the dynamical linkages and propagation of extreme precipitation events is imperative in deriving a clear picture of its associated changing tail risks with increasing moisture holding capacity of the atmosphere due to increasing global mean air-temperature. Here we investigate such linkage and propagational characteristics of summer extreme precipitation events (SEPEs) over Conterminous United States (CONUS) using the concept of Complex Network (CN) where CN simply is defined as a graph-theory based depiction of relation shared by various elements of a complex-dynamical system such as the atmosphere. The SEPEs are calculated based on the 95^th percentile daily rainfall at 0.5^ox0.5^o spatial resolution for CONUS for the time period of 1979-2017. The derived CN coefficients (e.g., betweenness centrality, clustering coefficient, orientation, and network divergence) reveal important structural and dynamical information about the topology and propagation of the SEPEs and improve understanding of the dominant meteorological patterns. The direction of propagation of SEPEs from the source-zones to the sink-zones are identified. The topological structure and spatial propagation of SEPEs are influenced by topography, moisture sources and dominant wind patterns.