[A-CG47] Dynamics of Oceanic and Atmospheric Waves, Vortices, and Circulations

[ACG47-15] Downward flux of wave energy in the lower troposphere over the Pacific Ocean

*Kaiwen Ye¹, Hidenori AIKI^2,3 (1.Nagoya University, 2.Institute for Space–Earth Environmental Research, Nagoya University, Nagoya, Japan, 3.Application Laboratory, Japan Agency for Marine–Earth Science and Technology)

Keywords:Storm track, Eliassen-Palm flux, Energy flux

Energy transfer plays a critical role in air-sea interaction. While previous studies have extensively examined wind input to the ocean, the transfer of atmospheric wave energy remains to be more explored. Traditional approaches commonly use group velocity vectors to trace wave propagation from source to sink regions. Wave activity is indefinite because of the beta in Coriolis parameter. In contrast, wave energy flux provides a robust framework for analyzing energy budgets. Some of air-sea energy interactions originate from storm tracks in the atmosphere. We have investigated the vertical structure of wave energy flux in the atmosphere, especially in the lower troposphere using the Japanese 55-year Reanalysis dataset. Our analysis focuses on the monthly climatology of vertical wave energy flux in the lower troposphere, which is crucial to air-sea interactions. Our results reveal that magnitude of the downward energy flux at 900 hPa is about 100 times greater than wind input to ocean at the surface. The downward wave energy flux dominates in the lower troposphere associated with both cyclones and anticyclones within the midlatitude storm track regions. The downward flux of wave energy in the lower troposphere is consistent with the traditional views of upward Eliassen-Palm (EP) flux when interpreted in terms of relative flow velocity. The phase speed of eastward-propagating storms is estimated based on the ratio of wave energy flux to EP flux and is compared with the phase speed derived from Fourier transform analysis. The present study will contribute to a deeper understanding of atmospheric waves and energy exchange between the atmosphere and ocean.