Vertical Resolution Dependence of Gravity Wave Momentum Flux Simulated by an Atmospheric General Circulation Model

Tuesday, 16 December 2014
Shingo Watanabe, JAMSTEC Japan Agency for Marine-Earth Science and Technology, Kanagawa, Japan, Kaoru Sato, University of Tokyo, Bunkyo-ku, Japan, Yoshio Kawatani, JAMSTEC, Yokohama, Japan and Masaaki Takahashi, Atmosphere and Ocean Research Institute University of Tokyo, Tokyo, Japan
Dependence of gravity wave spectra of energy and momentum flux on atmospheric general circulation models’ (AGCM) horizontal resolution and time step has been intensively studied. In contrast, much less attention has been paid for dependence of those gravity wave parameters on models’ vertical resolution. The present study demonstrates dependence of gravity wave momentum flux in the stratosphere and mesosphere on the model’s vertical resolution, which is evaluated by using an AGCM with a horizontal resolution of about 0.56o. We performed a series of sensitivity test simulations changing only the model’s vertical resolution above a 8 km height, i.e., dz = 200 m, 300 m, 400 m, 500 m, and 1000 m; constant about 10-100 km height, and found that inertial gravity waves with short vertical wavelength simulated at higher vertical resolution likely play important roles in determination of gravity wave momentum flux in the stratosphere and mesosphere.