Assessing environmental conditions associated with spatially varying rainfall structure of North Atlantic tropical cyclones: An object‐based climatological analysis

Abstract

AbstractThis study utilizes geographic information system‐based shape analyses with spatial regressions to examine the spatial variations in the relationships between North Atlantic TC rain field patterns and the environmental conditions. We measure the area, solidity, dispersion and closure of rain fields associated with North Atlantic tropical cyclones (TCs) during 1998–2014 from satellite‐based rain rate estimates. The potential contributing factors examined include storm intensity, translational speed, sea surface temperature, total precipitable water, upper‐tropospheric divergence, deep‐layer vertical wind shear and distance to land. Spatial metrics of rainfall, TC attributes and environmental conditions are aggregated onto a hexagon grid, and the average values are used in regression models. Spatial autoregressive regression and geographically weighted regression are applied to investigate the relationships between contributing factors and rainfall patterns. Storm intensity is positively correlated with area, solidity and closure and negatively correlated with dispersion. Higher moisture and larger upper‐level divergence contribute to a larger rainfall field with a more dispersed and less solid pattern, especially over the western Gulf and the western Caribbean. Wind shear and storm motion affect rain field patterns differently depending on the juxtaposition and relative magnitude of storm motion and wind shear vectors and thus exhibit more regional variations. This research further highlights the importance of incorporating a spatial component into the research on TC rainfall climatology. An improved understanding of basin‐wide and sub‐basin‐wide relationships between TC rain fields and contributing factors would benefit rainfall forecasting and hazard mitigation.