An examination of high latitude upper mesosphere dynamic stability using the Nippon/Norway Svalbard Meteor Radar

Abstract

Using wind measurements from the recently installed Nippon/Norway Svalbard Meteor Radar, (NSMR) at 78°N, 16°E, we have derived wind shears, and, combining these with model Brunt-Väisälä frequencies, have determined estimates of the gradient Richardson Number. These Richardson Number estimates parameterise the degree of stability of the upper mesosphere at a height of around 90 km. We find indications of dynamic instability in spring and autumn, with greater stability in summer.