Upward Transport of Westerly Momentum due to Large-Scale Disturbances in the Equatorial Lower Stratosphere

Abstract

The vertical transport of zonal momentum due to the large-scale westward moving disturbances with a period of about four days in the westerlies of the equatorial lower stratosphere is studies by spectral analyses for the data of special observations over the tropical Pacific during the periods from March to July 1958 and from April to July 1962. By neglecting the effects of heat source and horizontal advection in the thermodynamic equation, the quadrature-spectral estimates between the zonal wind component and temperature are shown to give a measure of the vertical transport of zonal mementum. An analysis at the 50-mb level shows that the vertical transport of westerly momentum due to the disturbances in the period range of three to five days is upward all over the equatiorial area within the latitudes of ten degrees. The maximum upward transport of westerly momentum at this level is roughly 2×10 (m.sec1)2 at about 6° latitude, and rather less at the equator. The disturbances are shown to carry the sensible heat poleward, and upward transport of wave energy due to the disturbances is implied.