Gravity wave distribution at low and mid-latitudes
from the Nested Regional Climate Model
Han-Li Liu, Jimy Dudhia, Bill Kuo
National Center for Atmospheric Research
Gravity waves are generated from the orography, convection, and spontaneous adjustment of unbalanced jet flow, with spatial scales from 10-1000 km and temporal scales between buoyancy frequency and intertial frequency. The gravity waves can significantly impact the energy and momentum budget, the transport and mixing of atmospheric species, and stability and variability in the middle and upper atmosphere. The vastly different spatial and temporal scales and the global distribution of the gravity waves pose a stiff change for both observational and numerical studies of the gravity waves. In recent years, very high resolution numerical simulations can be afforded with the increasing computational power, and gravity waves at increasingly finer scales can be resolved in regional and even global domains. In this study, results from the Nested Regional Climate Model (NRCM) are examined. The NRCM has a global coverage between 45S and 45N (thus a channel model) with horizontal resolution of 36 km, and extends from the ground to ~30 km. The potential energy density of the gravity wave perturbations between 100-1000km from the model is compared with that obtained from GPS measurements. Analyses of gravity wave characteristics, energy and momentum flux, their distribution at low and mid-latitudes, and their seasonal variation in the upper troposphere and lower stratosphere will be presented.