Parameter Tree:
EARTH SCIENCE > ATMOSPHERE > ATMOSPHERIC WINDS > UPPER LEVEL WINDS > BOUNDARY LAYER WINDS

Definition:
Winds measured in the layer of fluid near a boundary that is affected by friction against that boundary surface, and possibly by transport of heat and other variables (such as winds) across that surface. In meteorology, this is the atmospheric boundary layer.

Reference:
Glossary of Meteorology, American Meteorological Society