High-resolution quasi-idealized experiments for future and present-day based upon composites from a decades-long set of recurving landfalling (RCL) North Atlantic ET cases

We present a high-resolution quasi-idealized experiment based upon
composites from a decades-long set of recurving landfalling (RCL) North
Atlantic extratropical transition (ET) cases. Following Jung and Lackmann
(2021), we apply the track-based classification method of Colbert and
Soden (2012) to the historical database (1979 to 2018) of North Atlantic
RCL ET events; recurving landfalling tropical cyclones (TCs) are defined
as those which cross 70°W north of 25°N or cross 65W north of 40N and
threaten the U.S. East Coast. We use the Atlantic Hurricane Database
(HURDAT2) best-track data (Landsea and Franklin 2013); the track-based
classification procedure yields 37 RCL ET cases over the 40-year period.
To minimize the spread of the selected ET cases in terms of time to
complete transition, we apply a threshold of 36 h as in Jung and Lackmann
(2021). As HURDAT2 only specifies when transition is complete but does not
provide the timeline of the transition, we supplement it with the cyclone
phase space (CPS) method of Hart (2003) to diagnose onset and completion
times of ET; ET events are first identified by HURDAT2 and then we compute
the CPS parameters to confirm the ET timeline for each event using the
ERA5 reanalysis dataset (Hersbach et al. 2020). This filtering process
yields 21 RCL ET cases. This dataset is initialized by randomized 15-case
composites selected from the 21 RCL ET cases as in Jung and Lackmann
(2021). This dataset was used to produce figures and tables in the
manuscript of Jung and Lackmann (2023, in review).  Due to
storage limitations, the full dataset is much too large to be published (~
500GB). Instead, a subset consisting of 3-hourly atmospheric temperature
at 17 vertical levels, zonal and meridional wind at 17 vertical levels, 3
hourly accumulated precipitation, mean sea level pressure, 10-m zonal and
meridional wind, sea surface temperature, and relative humidity at 17
vertical levels is presented. If you wish to access the full dataset,
please contact one of the authors.