| << | Convection, Turbulence and Precipitation | >> |
Abstract
In recent years sodars have been deployed to both the Antarctic and Greenland ice sheets to aid in the interpretation of the chemical exchanges between the ice/snow surface and the overlying atmosphere. These boundary layers often obtain depths of a few tens of meters trapping NOx released through photolysis of nitrate in the snow. Designing sodars to work in a polar environment with high resolution, minimum range, and reliability has been a challenge. For example, we have used a bistatic arrangement with nearly collocated transmitters and receivers to avoid contamination of the return signal from ringing of the transducer. However, the greatest value of sodars has been in their integration with chemical time series and profiling in addition to measurements of turbulence, wind and temperature on short towers. In this presentation we will describe these integrated observing approaches and the insights into polar chemistry gained from them. For example, with surface emissions of nitric oxide (NO) from snow, its vertical profile measured with a tethered balloon system provides significant interpretive value for sodar echo returns viewed either in facsimile mode or as averaged amplitude profiles. It is our hope that results from the rather simple boundary layer environment over ice sheets will provide algorithms that can be applied to more complex operating environments.