Historical Variability and Lifecycles of North Atlantic Midlatitude Cyclones Originating in the Tropics

Abstract

North Atlantic tropical and post‐tropical cyclones impact midlatitude regions, but the inhomogeneous observational record of the latter stages of tropical cyclones precludes many climatological analyses. The frequency of tropical‐origin storms basin‐wide is projected to increase under anthropogenic climate change, so establishing confidence in our knowledge of their historical variability and lifecycles—against which climate model simulations may be evaluated—is important. We used a Lagrangian feature‐tracking algorithm to identify tropical cyclones that impacted Northeast North America and Europe in seven global reanalysis data sets, distinguishing systems that retained warm‐core structures or underwent warm seclusion from those that underwent extratropical transition, acquiring cold‐core, frontal structures. Over the last four decades, ∼25% and ∼10% of tropical‐origin cyclones made landfall across Northeast North America and Europe, respectively, as warm‐core systems, with, on average, higher wind speeds than cold‐core systems. Historical warm‐core and cold‐core landfalls also exhibit distinct tracks, likely responding to differing steering flow and midlatitude conditions.

Contrasting Responses of Atlantic and Pacific Tropical Cyclone Activity to Atlantic Multidecadal Variability

“…To assess the sensitivity of TC responses to feature‐tracking algorithm, we used a different algorithm named TRACK (K. I. Hodges, 1995, 1999) and compared its results with those derived from the TempestExtremes. The TRACK algorithm was widely applied to track TCs in reanalyzes and GCM outputs (Baker et al., 2021, 2022; K. Hodges et al., 2017; Roberts et al., 2020a, 202b). Different from TempestExtremes, TRACK uses relative vorticity in various vertical levels as the primary feature‐tracking variables.…”

“…Hodges, 1995Hodges, , 1999 and compared its results with those derived from the TempestExtremes. The TRACK algorithm was widely applied to track TCs in reanalyzes and GCM outputs (Baker et al, 2021(Baker et al, , 2022K. Hodges et al, 2017;Roberts et al, 2020a, 202b).…”

Tropical cyclones position and intensity in the Southwest Indian Ocean as represented by CFS and ERA5 atmospheric reanalysis datasets

“…The evaluation of tropical cyclones on gridded datasets is strongly dependent on the ability to identify and track such systems. The identification and tracking of the systems in both reanalyses are performed using the TRACK algorithm developed by Hodges (1994Hodges ( , 1995Hodges ( , 1999, a well-established and largely used methodology to track and identify cyclonic systems in reanalyses datasets (e.g., Baker et al, 2021;Gramcianinov et al, 2020;Hodges et al, 2003Hodges et al, , 2011. In this methodology, potential cyclonic systems are tracked using relative vorticity fields computed from 6-hourly zonal and meridional wind components.…”

Anthropogenic Effects on Tropical Cyclones near Western Europe

“…Counterintuitively, climatological analysis suggests that TCs hitting Western Europe are not as rare as one might think. Approximately 10% of Atlantic TCs have made landfall in Europe in the past four decades 5 , i.e., about one European landfall per year. More than half of the storms reaching Europe from the Atlantic tropics retain a warm cyclone core, bringing extreme winds at landfall 6 .…”