Buoyant Subrange Observed in the Stably Stratified Atmospheric Surface layer

Abstract

The vertical wind component (w) and air temperature fluctuations (θ) observed at a height of 11.25 m by sonic anemometer-thermometers on 12 December 1986 at Kochi, Japan AMM to give experimental support for the existence of a buoyant subrange following the breakdown of wave motions that occur normally in the Stably stratified atmospheric surface layer after sunset. An important favors the occurrence of the buoyant subrange in the present observation is the downdraft formed ahead of the land breeze front during the slow transition from the sea breeze to the land breeze. The downdraft triggers the breaking of the wave. Examination of the fine records of w suggest that the disturbance induced into the wave are suppressed by the negative buoyancy related to the formation of the buoyant subrange during breaking. The wave feeds part of its energy into turbulence, however, which ultimately is enhanced and increases because of nonlinear interaction with w-fluctuation.