The paper is devoted to the problem of the role of an presstire field in the adjustment of the wind in a neutral nonlinear barotropic planetary boundary layer(PBL);Evidence suggests that any initial wind field will adjust itself towards a given pressure pattern through absolute vorticity oscillation and viscous coefficient dissipation,leading to the adjustment time scale[O(t^(-3/2))],faster than[O(t^(-1)] for quasi geostrophic adaptation in the free atmosphere.