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GEOPHYSICAL RESEARCH LETTERS, VOL. 30, NO. 8, 1438, doi:10.1029/2003GL016960, 2003

Large potential energy of gravity waves over a smooth surface with little convection: Simulation and observation

Yoshio Kawatani

Center for Climate System Research, University of Tokyo, Tokyo, Japan


S. K. Dhaka

Center for Climate System Research, University of Tokyo, Tokyo, Japan
Department of Physics, Rajdhani College, University of Delhi, Delhi, India


Masaaki Takahashi

Center for Climate System Research, University of Tokyo, Tokyo, Japan


Toshitaka Tsuda

Radio Science Center for Space and Atmosphere, Kyoto University, Kyoto, Japan


Abstract

A numerical experiment is conducted using an Atmospheric General Circulation Model (AGCM) to investigate the presence of the large potential energy over a region of low topography and little convective activity, focusing on the tropical Atlantic region (10°E to 20°W, 0° to 20°S). It is found that gravity waves with a time period of 24 hours are excited near the Equator (∼5°–15°N) in a region of large moist heating extending vertically up to 10–13 km. The gravity waves propagate upward from this region with a bias toward the south and are manifested as large energy fluxes in the cross equatorial region. Enhanced energy fluxes are therefore simulated at 20–30 km altitude over a region with no significant source of gravity waves, and are confirmed using Global Positioning Satellite/Meteorology (GPS/MET) experiment data.

Published 26 April 2003.

Index Terms: 3319 Meteorology and Atmospheric Dynamics: General circulation; 3337 Meteorology and Atmospheric Dynamics: Numerical modeling and data assimilation; 3334 Meteorology and Atmospheric Dynamics: Middle atmosphere dynamics (0341, 0342); 3374 Meteorology and Atmospheric Dynamics: Tropical meteorology.

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Citation: Kawatani, Y., S. K. Dhaka, M. Takahashi, and T. Tsuda (2003), Large potential energy of gravity waves over a smooth surface with little convection: Simulation and observation, Geophys. Res. Lett., 30(8), 1438, doi:10.1029/2003GL016960.