THE PLANETARY BOUNDARY LAYER WIND OVER CHRISTMAS ISLAND

Abstract

Wind observations in the planetary boundary layer over an atoll near the Equator were made using the double-theodolite pilot balloon method. The observed mean wind profile is representative of boundary layer flow over a homogeneous surface with a very low value of the Coriolis parameter. The wind is predominantly easterly with a small backing with height. Analysis of the wind profile suggests that the component of motion along east-west direction is approximately geostrophic; however, the component along the north-south direction is highly nongeostrophic. The analysis also indicates that the change in the wind direction with height is controlled mainly by the height variation of the horizontal pressure gradient.