1. What Can Hurricane Sam (2021) Tell Us About Extreme Ocean Waves Under Tropical Cyclones?
- Author
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Zhao, X., Oruba, L., Hauser, D., Zhang, B., and Dormy, E.
- Subjects
ROGUE waves ,EXTREME weather ,RADAR cross sections ,TECHNOLOGICAL innovations ,STORM surges - Abstract
We investigate the ocean wave field under Hurricane Sam (2021). Whilst measurements of waves under Tropical Cyclones are rare, an unusually large number of quality in situ and remote measurements are available in that case. First, we highlight the good consistency between the wave spectra provided by the Surface Waves Investigation and Monitoring (SWIM) instrument onboard the China‐France Oceanography SATellite, the in situ spectra measured by National Data Buoy Center buoys, and a saildrone. The impact of strong rains on SWIM spectra is then further investigated. We show that whereas the rain definitely affects the normalized radar cross section, both the innovative technology (beam rotating scanning geometry) and the post‐processing processes applied to retrieve the 2D wave spectra ensure a good quality of the resulting wave spectra, even in heavy rain conditions. On this basis, the satellite, airborne and in situ observations are confronted to the analytical model proposed by Kudryavtsev et al. (2015, https://doi.org/10.1002/2015JC011284). We show that an extended fetch mechanism may be invoked to explain the large significant wave height observed in the right front quadrant of Hurricane Sam. Plain Language Summary: Wave measurements in Tropical Cyclones can be performed by radars onboard satellites or aircrafts, and by in situ devices such as buoys or saildrones. In 2021, a saildrone sailed in Hurricane Sam, providing the first video images of extreme weather in a hurricane, as well as wind and wave measurements. Hurricane Sam was also monitored by the Surface Waves Investigation and Monitoring instrument onboard the China‐France Oceanography SATellite, which measures the wave energy distribution. We explain why these measurements are reliable, despite the heavy rain conditions. Combining all observational data available for Hurricane Sam, we show that the most extreme waves are consistent with the so‐called extended‐fetch mechanism, whereby waves traveling at a velocity similar to the TC displacement can undergo a phenomenal growth. Key Points: We take advantage of the unusually large number of observations in Hurricane Sam (2021) to study the physics of waves under a hurricaneThe innovative China‐France Oceanography SATellite‐Surface Waves Investigation and Monitoring instrument provides 2D wave spectra which are reliable despite the heavy rain conditions in hurricanesThe trapped wave mechanism, or extended fetch, scenario can be successfully compared with observations by a saildrone and a National Data Buoy Center buoy [ABSTRACT FROM AUTHOR]
- Published
- 2024
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