Projections of the large-scale drivers influencing the North Atlantic tropical cyclones

Understanding the evolution of tropical cyclones (TC) over the 21st century under a changing climate is essential to improve the resilience of the North American electricity system. In this regard, several studies have projected future changes in TC behavior by detecting and tracking their evolution using climate simulations. One of the key limitations of climate models, specifically attributed to their limited spatial resolution, is that they are unable to simulate all the non-linear interactions between various components of the Earth system. Hence, in this study, instead of tracking TCs in the coarse spatial-resolution climate models, we investigate the evolution of the large-scale drivers influencing the North Atlantic TCs over the mid-future (2041-2060) and far-future (2081-2100). We use five bias-corrected simulations under two shared socio-economic pathway scenarios from the 6th generation Coupled Model Intercomparison Project. In particular, we examine the changes in the large-scale thermodynamic and atmospheric dynamic indicators favorable for TCs, namely sea surface temperature, wind shear, and lapse rate. 

Our results show an increase in the seasonal mean North Atlantic sea surface temperature (between +1 and +3°C), the length of the TC season (between +2 and +5 months), and the ocean heat content (3-6 times) relative to the historical period (1995-2014), while a decrease in the temperature lapse rate (between -0.8% and -1.45%) over both the mid-future and far-future. We find no significant changes in the vertical wind shear under a changing climate. These results suggest an increase in both the frequency and intensity of TCs over the North Atlantic, the latter by 2.6%-5.2% on average. Additionally, our results show a plausible reduction in the conditions favorable for TCs by mitigating from high-emission to moderate-emission scenarios.