Stratospheric gravity wave simulation over Greenland during 24 January 2005

Abstract

The “Advanced Regional Prediction System” forecast model is extended up to the stratopause and over the entire hemisphere to simulate gravity waves during 24 January 2005. With a 15‐km horizontal resolution, the simulation produces dominant gravity wave features near Eastern Greenland that are associated mainly with orographic forcing by the Greenland terrain. The simulated wave temperature perturbations compare favorably with radiance perturbations from NASA Atmospheric Infrared Sounder observations. In the upper stratosphere (40–50 km), vertical overturning of the isentropes suggests the occurrence of wave breaking just east of Greenland that leads to a tremendous reduction of wave amplitudes. The associated flux divergence produces horizontal flow deceleration of 12–120 m s−1 day−1 and coincides with areas of depleted stratospheric wind speed, suggesting strong interactions between orographic gravity waves and the polar vortex. A simulation using the coarser 50‐km horizontal resolution produces gravity waves of significantly weaker amplitudes.