Climatological Characteristics of Surface-Based Inversions over the Arctic and Antarctic

Surface-based inversions (SBI) are a frequent feature of the atmospheric boundary layer in the Arctic and Antarctic and influence vertical mixing of energy, moisture and pollutants, cloud formation, and surface destruction of ozone. Recent studies also relate SBIs in both hemispheres to variability of sea ice, and thus planetary albedo, an important factor in climate feedback mechanisms. However, climatological SBI properties in the Polar Regions have not been fully characterized or quantified, nor have climate model simulations of SBIs been compared to observations in a comprehensive manner.

This study examines climatological characteristics of SBIs using up to 50 yr of twice-daily radiosonde observations from 113 Arctic and 19 Antarctic stations. Three SBI characteristics are studied: frequency of occurrence, depth (from the surface to the inversion top), and strength (temperature difference within the SBI). We will present the spatial, seasonal, and diurnal variability of these characteristics in both Polar Regions. Results from radiosondes will be compared with SBI characteristics in two state-of-the-art climate models (NCAR's CAM3 and NOAA/GFDL AM3), and with reanalysis data (ERA40). Finally, we examine multidecadal change in SBI characteristics in the radiosonde record.