Vertical wind shear in the lowest layers of the atmosphere over Thumba during winter months-A preliminary study

Abstract

Vertical wind shear in the lowest layers of the atmosphere over Tumba-an equatorial station -has been studied. Wind data from the surface up to 200 ft were collected at different altitudes (8, 31, 56, 134 and 200 ft) during the months December 1963 and January 1964, for the above study. Analysis reveals that appreciable wind shear exists very close to the surface, i,e in the layer up to 31 ft. On the other hand, in the layer 31-200 ft, the shear values are not considerable. It is further observed that the shear magnitude reaches maximum in the afternoon, The frequency of occurrence of shear magnitudes more than 10 kts/30 m (which, as  indicated by ICAO, is important for supersonic transport operation) is high in the lowest layer round about l430 IST during the winter months.