Insights and puzzles in understanding atmospheric boundary layer—surface chemistry interactions over the Antarctic high plateau

Antarctica is one of the most dramatic topographic features on the face of the Earth extending over half an atmospheric scale height into the troposphere with a horizontal extent exceeding the Rossby Radius of deformation. From the heroic era of exploration to the present, the surface winds over Antarctica have dominated the human experience with remarkable persistence over the interior, strength on the coast, as well as a seemingly straightforward dynamical explanation. With new acoustic probing of the boundary layer beginning in the 1970s at the South Pole, this picture has changed, revealing unexpected complexity (even in the absence of a diurnal insolation cycle) and sensitivity of the boundary layer, on daily to decadal time scales, to the circulation in the upper-troposphere/lowermost stratosphere. Among the surprises, recent studies of reactive nitrogen exchanges with the snow surface have revealed unexpectedly high concentrations of nitric oxide (>900 pptv) and shown the dominant role of the stable boundary layer in mediating these exchanges in concert with changes in the upper tropospheric circulation. We will describe new insights into the character of vertical exchange processes when boundary layer and the puzzles remaining in linking long-range transport with vertical exchange mechanism in a data sparse environment.