Meso‐Scale Effects of Agriculture and a Large Prairie Lake on the Atmospheric Boundary Layer

Thermal gradients were measured in the atmospheric boundary layer over an extensive agricultural region using an instrumented aircraft and a mobile ground station mounted on an automobile. It was noted that sharp changes in the temperature of the surface produce similar temperature changes in the atmosphere above. Near the surface the temperature discontinuities in the atmosphere were located almost immediately above the heat sources or sinks. But higher in the atmosphere, the cooled or heated air persisted for appreciable distances down wind. A large lake and an irrigated region produced 3.0 C and 2.0 C cooling, respectively at 20-m elevation, and virgin prairie caused a temperature increase of 2.0 C in the atmosphere at 20 m. The temperature changes indicated are statistically significant compared, to the temperature of prairie air 8 km up wind at the same elevation.