Project P5 is motivated by the need to compute biophysically meaningful surface heat and momentum budgets for heterogenous land surfaces as an essential component in the L-A feedback chain. Over the past decades, progress in understanding and quantifying the impact of surface heterogeneity has been made for the canonical cases of perpendicular and parallel airflows relative to a heterogeneity jump. In contrast, the turbulent structures for the most common case of oblique airflows, here defined as attack angles between 10° and 80° relative to the patch edge, are not mechanistically understood and their impact on surface fluxes escapes quantification. P5’s objective is therefore to detect, understand, and conceptualize these oblique airflows moving across LAFO’s agricultural patches. Our central hypothesis is that zones of enhanced surface fluxes through localized but non-stationary turbulent motions create a transitional boundary layer in which area-averaged fluxes are inflated and enhance L-A feedbacks.
We analyze spatially explicit measurements from high-resolution fiber-optic distributed sensing (FODS) of air temperatures in the surface and crop layers, wind speed and turbulence kinetic energy on scales of seconds and decimeters over hundreds of meters. FODS also observes soil temperature and moisture, and the distribution of solar radiation at scales of decimeters and tens of seconds combined with classic sensor networks above the patches planted in winter wheat and maize.
