| 英文摘要: | To the Editor —
Meteorological agencies of Ireland and the UK have confirmed that winter (December to February) 2013–2014 (W2013–14) set records for precipitation totals and the occurrence of extreme wind speeds1, 2, 3. Less clear is whether storminess (characterized as the frequency and intensity of cyclones) during W2013–14 was equally unprecedented. We assessed multidecadal variations in storminess by considering frequency and intensity together and found that in the context of these large-scale cyclone characteristics, W2013–14 was indeed exceptional. Given the potential societal impacts, there is clearly a need to better understand the processes driving extreme cyclonic activity in the North Atlantic.
We applied an automated detection routine4 (see Supplementary Information) to the National Centers for Environmental Prediction and National Center for Atmospheric Research Reanalysis 1 (NCEP1)5 and the 20th Century Reanalysis (20CR)6 datasets to determine cyclone frequency and intensity over four domains (Fig. 1a). Storminess (I) was calculated7 as Iy = CyLy, where C is the number of cyclones observed during each winter in year y and L is their mean local Laplacian (intensity). Based on the NCEP1 dataset, we found that W2013–14 was the stormiest in the 66-year record (1948–1949 to 2013–2014) across the North Atlantic, due to unprecedented cyclone intensity and frequency for the mid- and high-latitude North Atlantic, respectively (Fig. 1b). Cyclone intensity has increased over the North Atlantic, consistent with trends in NCEP1 near-surface wind speeds (see Supplementary Information) and with previous investigations into cold-season cyclone activity over the North Atlantic8, 9. W2013–14 is also ranked as the stormiest on record for the Ireland–UK domain, where the combination of high cyclone frequency and above average cyclone intensity resulted in exceptional storminess. |