A new look at stratospheric sudden warmings. Part I: Climatology and modeling benchmarks

Stratospheric sudden warmings are the clearest and strongest manifestation of dynamical coupling in the stratosphere-troposphere system. While many sudden warmings have been individually documented in the literature, this study aims at constructing a comprehensive climatology: all major midwinter warming events are identified and classified, in both the NCEP-NCAR and 40-yr ECMWF Re-Analysis (ERA-40) datasets. To accomplish this a new, objective identification algorithm is developed. This algorithm identifies sudden warmings based on the zonal mean zonal wind at 60 degrees N and 10 hPa, and classifies them into events that do and do not split the stratospheric polar vortex.