High Arctic observations of mesospheric inversion layers

Rayleigh lidar measurements of middle atmospheric temperatures obtained in the High Arctic at Eureka (80°N, 86°W) are examined for evidence of mesospheric inversion layers with overlying nearly‐adiabatic lapse rates. Inversion layers are identified in 5.4 ± 0.5% of the measurements, a rate considerably lower than is observed at midlatitudes. The altitude distribution for the Arctic inversions is similar to that found at midlatitudes. No phase progression or relationship with stratospheric gravity wave activity was found. The observations have important consequences for theories of the mesospheric inversion layer.