Understanding the Spatial Organization of Simultaneous Heavy Precipitation Events Over the Conterminous United States
We introduce the idea of simultaneous heavy precipitation events (SHPEs) to understand whether extreme precipitation has a spatial organization manifested as specified tracks or contiguous fields with inherent scaling relationships. For this purpose, we created a database of SHPEs using ground-based precipitation observations recorded by the daily Global Historical Climatology Network (GHCN-D) across the conterminous United States during 1900–2014. We quantified the spatial distribution of the centroids and principal axes of SHPEs and their quasi-elliptical manifestations, azimuthal orientations, and areal extents on the ground. Four seasons, December-January-February (DJF), March-April-May (MAM), June-July August (JJA), and September-October-November (SON), are considered to examine the spatial patterns and associated large-scale atmospheric circulations. Power laws explain SHPEs' underlying area scaling behavior in all four seasons.
Quantifying the characteristics of SHPEs and modeling their footprints can improve the projections of flood risk and understanding of damages to interconnected infrastructure systems. The framework and findings presented in this study can help develop improved flood risk management methods by public/private planners and agencies. The database can be used by the Earth system scientists working on extreme events to explore new research avenues. The SHPE database provides a unique tool for exploring and predicting large river floods' spatial extent. It can also be used to explore whether the current generation of global circulation models adequately represents the spatial features depicted in these ground-based measurements and how they could be improved to better describe these spatial features.
This study presents a new way of quantifying the spatial manifestation of extreme precipitation. We introduce SHPE —simultaneous heavy precipitation event— to understand the daily compound effects of the spatially oriented extreme precipitation events (>99th percentile) for each of the DJF, MAM, JJA, and SON seasons across the conterminous United States (1900–2014). The spatiotemporal characteristics of SHPEs are assessed to discern their properties in different seasons. Their spatial manifestations are quantified using power laws for areal extents and inverse logistic functions for the probability of centroids. Ultimately, these models can be used as a basis for several floodplain management strategies and reliability analyses of the infrastructure systems.