Observations of extreme temperature and wind gradients near the summer mesopause during the MaCWAVE/MIDAS rocket campaign -: art. no. L24S06

We present measurements of extremely large gradients of temperature and zonal wind near the arctic summer mesopause obtained with sodium lidar and falling spheres during the MaCWAVE/MIDAS rocket and ground-based measurement campaign performed at the Andoya Rocket Range (ARR) and the ALOMAR observatory (69.3degreesN, 16.0degreesE) in July 2002. The gradients appear to result from strong gravity wave forcing of the summer mesopause, vertical scale compression and amplitude increases accompanying increasing stratification and decreasing intrinsic phase speeds, and the turbulent transport accompanying wave instability in the lower thermosphere. Zonal wind gradients are found to exceed 100 m s(-1) km(-1), while temperature gradients range from super-adiabatic to similar to40 to 100 K km(-1). We also explore the implications of these large gradients for further instability of the gravity wave and mean fields.