Ocean currents show global intensification of weak tropical cyclones
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836; e-ISSN 1476-4687, more
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| Authors | | Top |
- Wang, G.
- Wu, L.
- Mei, W.
- Xie, S.-P.
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| Abstract |
Theory and numerical modelling suggest that tropical cyclones (TCs) will strengthen with rising ocean temperatures. Even though models have reached broad agreement on projected TC intensification, observed trends in TC intensity remain inconclusive and under active debate in all ocean basins except the North Atlantic, where aircraft reconnaissance data greatly reduce uncertainties. The conventional satellite-based estimates are not accurate enough to ascertain the trend in TC intensity suffering from contamination by heavy rain, clouds, breaking waves and spray. Here we show that weak TCs (that is, tropical storms to category-1 TCs based on the Saffir–Simpson scale) have intensified in all ocean basins during the period 1991–2020, based on huge amounts of highly accurate ocean current data derived from surface drifters. These drifters have submerged ‘holy sock’ drogues at 15 m depth to reduce biases induced by processes at the air–sea interface and thereby accurately measure near-surface currents, even under the most destructive TCs. The ocean current speeds show a robust upward trend of ~4.0 cm s−1 per decade globally, corresponding to a positive trend of 1.8 m s−1 per decade in the TC intensity. Our analysis further indicates that globally TCs have strengthened across the entirety of the intensity distribution. These results serve as a historical baseline that is crucial for assessing model physics, simulations and projections given the failure of state-of-the-art climate models in fully replicating these trends. |
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