Changes in the concurrence of atmospheric rivers and explosive cyclones in the North Atlantic

The explosive development of extratropical cyclones and the presence of atmospheric rivers play a crucial role in driving some types of extreme weather in the mid-latitudes, like compound flood-windstorm events. Although these phenomena are individually well-established and their relationship has been studied previously, there is still a gap in our understanding of how a warmer climate may affect their concurrence. Here, we focus on evaluating the current climatology and assessing changes in the future climate of the concurrence between atmospheric rivers and explosive cyclones in the North Atlantic.

We use both the ERA5 and ERA-Interim reanalysis between 1980 to 2009 from October to March to evaluate the concurrence of atmospheric rivers and explosive cyclones in the current climate. To accomplish this, we first independently detect and track atmospheric rivers and extratropical cyclones. Next, we classify each cyclone as either explosive or non-explosive and define concurrence with an atmospheric river if the latter is detected within 1500 km of the minimum sea level pressure of the cyclone. We further analyse several CMIP6 climate models for the historical scenario (1980-2009) and for the future scenarios SSP1-2.6, SSP2-4.5 and SSP5-8.5 at the end of the century (2070-2099).

Our findings reveal that atmospheric rivers are more often detected in the vicinity of explosive cyclones than non-explosive cyclones in all datasets. Moreover, we identified a significant increase in the concurrences and the atmospheric river intensity in all the future scenarios analysed. As such, our work provides a novel statistical relation between explosive cyclones and atmospheric rivers in climate projections, a characterization of both in future climates and a new climatology of the concurrences for a higher-resolution reanalysis.