Multi-Centennial Spatial Coherency Among Atlantic Tropical Cyclones From Simulated and Reconstructed Storm Records

Abstract

Proxy-based reconstructions of long-term Atlantic tropical cyclone (TC) variability reveal low-frequency oscillations in regional TC landfalls over the Common Era. However, the limited spatial coverage and increased uncertainty of the proxy records complicates assessments of this feature. Here we present a new multi-ensemble set of synthetic TCs downscaled from the Last Millennium Reanalysis project, which is based on sea surface temperatures that more accurately reflect past conditions. Throughout ensemble members, there are coherent multi-centennial shifts in landfalls with persistent intervals of increased (decreased) occurrence along the eastern US concurrent with inverse activity in the southwest Caribbean and Gulf of Mexico, associated with basin-scale redistributions of storm tracks. The emergent TC-dipole from modeled climate provides context and support for its presence within proxy-reconstructions. Furthermore, dipole recurrence across ensembles demonstrates that it arises from sea surface temperature-informed climate processes. However, timing differences between ensembles indicate that transient atmospheric variability influences dipole position.