We gratefully acknowledge funding from the German Research Foundation (research group PANDOWAE, FOR896) and the Swiss National Science Foundation (Project 200021-130079). The detailed and constructive reviews from Gwendal Rivière and Rich Moore were very helpful for improving the clarity of the paper and highly appreciated. We are also very thankful for the detailed and insightful terminology discussion with Rich Moore and Ron McTaggart-Cowan. The code for the QG vertical motion diagnostic was derived from routines in NDDIAG, a diagnostics package developed and supported by NCAS-CMS (UK National Centre for Atmospheric Science Computational Modelling Services). We thank Sue Gray (University of Reading) for making this package available to us. We are also grateful to Patricia Heckendorn for developing an initial version of the DRW tracking algorithm and to Michael Sprenger for the composite tool. NASA is acknowledged for providing TRMM precipitation estimates.
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For brevity, from here on the term “Atlantic” denotes the North Atlantic region specified above, and “Pacific,” the North Pacific region.
ΔSLP (Bergeron) = ΔSLP (hPa) × [sin(60°)/sin(φ)]/24h, where φ denotes the averaged latitude of the cyclone center during this 24-h interval. The deepening rate is then determined as the maximum value of ΔSLP for all 24-h intervals along the DRW track.
This system is not registered by our tracking algorithm because the track disconnected at one time step due to too weak low-level PV when the system crossed the Appalachians.
These DRWs occurred at 0600 UTC 17 October 2002, 1200 UTC 6 March 2003, 1800 UTC 18 March 2004, 1200 UTC 16 December 2004, and 1200 UTC 22 January 2007 in the North Atlantic, and at 1200 UTC 7 October 2003, 1800 UTC 12 December 2005, 0600 UTC 4 November 2007, 1200 UTC 1 December 2007, and 0600 UTC 7 March 2010 in the North Pacific (dates refer to the start time of the 24-h intensification period).
The complete list of identified DRWs is available from the authors.