Sub-kilometric heterogeneity effects on the surface energy budget in BLLAST'11

In the experimental campaign Boundary Layer Late Afternoon and Sunset Turbulence (BLLAST), held at the foothills of the French Pyrenees in summer 2011, a specific sub-experiment was designed in order to estimate how the sub-kilometric terrain heterogeneities were able to generate motions that performed significant energy transport on a measurement point.

A complete measurement of the SEB was made in one point, while there were other measurements nearby, including radiosoundings, profilers and a 60-mast all at less than 1 km distance. Besides, flights of a small remotely-controled plane where made over the area, documenting the surface and air temperature heterogeneities. These were supplemented by flights with a remotely-controlled multicopter, that made horizontal transsects and low-level profiles at scales under the hectometer. Measurements of soil moisture around the site were also taken.

In this presentation, an estimation on the magnitude of the advection term in the temperature equation is made at the measured scales and its importance on the surface energy budget is discussed.