SAVANT: Stable Air Variability and Transport

Summary

Stable surface boundary layers (SBL) occur more than one-half the total time in mid-latitudes, yet our knowledge of the complexity of the near surface drainage and converging flows associated with stable conditions is very limited. Surface emissions produced in stable conditions are difficult to predict and display seemingly erratic high-concentration "clumps" which stay near the ground. These effects are seen in even shallow topographic conditions Some studies have measured converging background and drainage flows in mountain areas, however, few studies have examined this in less dramatic, but more common, topographic areas. In general, transport models and field sampling systems have not been adapted to converging flows. We propose a measurement campaign to address these open issues.

The goal of the proposed work is to quantify, through a field measurement campaign, the effects of converging shallow cold air drainage and background flow on aerosols transport and dispersion to specifically answer the following questions:

1. Under what conditions (i.e. cloud cover, threshold wind speed, and stability regime) do converging flows exist?
2. What spatial scale of flows are generated by converging drainage and background flows, and do these flows follow the current theories of wind speed dependence?
3. How is aerosol dispersion and transport influenced by turbulence forced oscillations generated in response to the collided flow?
4. What are the effects of intermittent turbulence on drainage and converging flow spatial and temporal variability of aerosol transport?