On the sources of gravity waves near the andes cordillera

In the present work we identified the atmospheric perturbations in the vicinity of the Andes Cordillera as sources of propagating (inertia-)gravity waves. Among them are the tropospheric jet, the deep convection and the mountain waves. Our study is based on joint data analyses and numerical simulations of the corresponding caseswith the help of the mesoscale WRF model. We succeded to isolate cases where only one of the above-mentioned sources is in action. The wave generation due to the jet is through the geostrophic adjustment process. Deep convection may generate waves through a direct thermal forcing, through the 'obstacle' effect and by the effect of 'mechanical oscillator'. We show that the direct thermal forcing exists but is weak. The wavelet analysis is used to identify the wave generation by deep convection. We identify the strong mountain wave cases by the WRF simulations and show that the two velocity components are in phase opposition at the level of the extrema of the amplitude of the mountain wave and identify the upward propagation of the emitted wave above.