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New mechanism of sea-spray generation and heat-mass transfer under stormy conditions

Name
Yuliya
Surname
Troitskaya
Scientific organization
IAR PAS
Academic degree
Dr.-Sci.
Position
Head of Department
Scientific discipline
Earth Sciences, Ecology & Environmental Management
Topic
New mechanism of sea-spray generation and heat-mass transfer under stormy conditions
Abstract
Basing on high-speed video we show that in air-flows with the surface stresses corresponding to the Force 8 wind, a special spray generation mechanism is activated. This regime is similar to bag-breakup mode of fragmentation of liquid in gaseous flows. Basing on general principles of statistical physics we develop statistics of the bag-breakup events, estimated the production rate of spray and showed, that at extreme winds “bag-breakup” is the dominant mechanism of sea spray production. This findings form a new basis for modeling the sea-spray and air-sea exchange at hurricane wind.
Keywords
sea spray, hurricane, polar low, heat-mass transfer
Summary

•Statistical analyses of sequences of frames of high-speed video has enabled us to prove that the dominant spray-generation mechanism in extreme winds relates to the bag-breakup fluid fragmentation regime. It activates at conditions corresponding to Force 8 wind, manifested as “spindrift”.

•Starting from general principles of statistical physics, we develop statistics of the bag-breakup events and determine the spray generation function, which is in good agreement with available experimental data

•Large droplets generated by bag-breakup significantly contribute to enthalpy and momentum flux:

 - They significantly increase the air-sea enthalpy flux at hurricane wind

- They enables to explain non-monotonous dependence of surface drag coefficient on wind speed peaking at 35-40 m/s.

   The effect is more pronounced for polar low, than for tropical cyclones