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  • APS Seminar Series — Seiji Kato (NASA LaRC)

    Title: Energy balance, radiative heating rate in the atmosphere, and entropy production

    Abstract: Temporal and spatial distribution of absorption of shortwave radiation and emission of longwave radiation by Earth drives dynamics in the atmosphere. In addition, net surface radiative flux drives evaporation of water vapor and the hydrological cycle. Shortwave radiation absorbed by Earth changes the form while the energy is transferred within the Earth system. Three large terms in achieving energy balance in the atmosphere are diabatic heating by precipitation, radiative cooling by longwave radiation, and dry static energy divergence by dynamics. Irreversible processes are also associated with conversion and transport of energy. When energy is transported poleward, entropy is produced by irreversible processes. Three large irreversible processes contributing entropy production at a global scale are frictional dissipation of turbulence, frictional dissipation of falling raindrops, and diabatic heating by water phase change associated with water vapor transport. At a steady state, entropy produced by non-radiative irreversible processes balances with entropy produced by absorption of shortwave radiation and longwave emission by the atmosphere. Therefore, accurate estimates of spatial and temporal distribution of shortwave and longwave radiative flux in the atmosphere is essential for achieving both energy balance and balance of entropy production. In this presentation, the importance of radiative flux profiles and net atmospheric radiative flux in both balancing energy and entropy production is discussed.