A Regional Analysis of Factors Affecting the Antarctic Boundary Layer During the Concordiasi Campaign

This study explores the regional variability in factors affecting the atmospheric boundary layer over continental Antarctica using high-resolution dropsonde observations from the Concordiasi campaign in the austral spring of 2010. Analyses show that although the surface-based inversion remains the dominant feature, well-mixed boundary layers, some with convective features, are observed with an occurrence frequency of 33% and 18% in West and East Antarctica, respectively. The boundary layer mixing is dominated by mechanical instability albeit with regional flavors caused by topographically forced winds, shortwave radiation, and air mass influences. In East Antarctica, the downsloping wind regime is prevalent, and related katabatic effects are strongest over high elevation slopes where the wind-induced turbulence is the primary cause of surface-based inversion erosion and boundary layer mixing. Previous studies over Dome C have demonstrated the significance of shortwave radiation for mixed layer development during the peak of summer. While such an effect is not dominant during spring, solar forcing may contribute to turbulent mixing in high latitude regions. Finally, well-mixed boundary layers are most frequently observed in the moist tongue region of West Antarctica, highlighting the importance of dynamical systems for boundary layer mixing.