During a hurricane, powerful winds churn and fan the ocean, leaving behind a swath of cold water that can last for weeks and weaken subsequent storms. But in parts of the ocean, these cold wakes aren鈥檛 lasting as long as they once did.
鈥淭his shortening of cold wake recovery time can give a second boost to hurricane intensity鈥� along with background warming due to climate change, says at the University of Delaware.
Tropical cyclones and hurricanes get their energy from heat in the ocean. Hotter sea surface temperatures raise the maximum potential intensity of storms. In turn, the storms themselves cool off the ocean as they travel along their path. That can rob any subsequent storms of energy when they pass over the 鈥渃old wake鈥� from the first storm.
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at the Pacific Northwest National Laboratory (PNNL) in Washington state and his colleagues analysed sea surface temperatures along hurricane paths in the Atlantic Ocean between 1981 and 2020 to understand how these cold wakes might be changing.
In the central Atlantic, where most hurricanes form, they found hurricanes today cool the ocean just as much as they once did, initially reducing temperatures along their path by about 0.26掳C on average. But they found that, since 2001, the cold wakes that follow have disappeared more quickly. These wakes generally haven鈥檛 persisted for long enough to weaken following storms.
The researchers estimate the effect of a missing cold wake on hurricane intensity is equivalent to 9 per cent of the rise in sea surface temperatures due to human-caused climate change since 1980. PNNL, which is operated by the US Department of Energy, did not respond to 快猫短视频鈥榮 request for comment from the researchers.
鈥淲e think in the future cyclones might get stronger due to a general increase in sea surface temperature,鈥� says Wang. 鈥淚f the recovery time of the cold wake decreases, that can definitely be a secondary effect.鈥�
According to the researchers, the shortening cold wakes are likely to be a consequence of climate change weakening the trade winds that fan off the ocean once a storm has passed.
npj Climate and Atmospheric Science
