Spatial and Temporal Characteristics of Satellite-derived Clear-sky Atmospheric Temperature Inversions in the Polar Regions

Many aspects of Arctic climate have undergone significant changes during recent decades. The low-level atmospheric temperature inversion, ubiquitous at high latitudes during most of the year, is affected by changes in cloud cover, surface temperature, and surface radiation. It has been shown previously that temperature inversion strength (temperature difference across the inversion) and depth (height) under clear sky conditions can be detected and estimated by the brightness temperature difference between the infrared window at 11 μm and a water vapor absorption band at 7.2 μm. This method makes possible the study of whether and how inversions have changed over the last 20 years using satellite data.

In this study, an empirical regression method is used to derive temperature inversion strength and depth under clear conditions in the polar regions based on High-resolution Infrared Radiation Sounder (HIRS) data over the period 1979-2000. The spatial characteristics and temporal trends in inversion strength and depth are analyzed. The relationship between changes in inversion characteristics and trends in surface temperature, cloud cover, and atmospheric circulation are investigated. Inter-satellite calibration is also discussed.