A case of very low latitude occurrence of the subtropical Jet Stream over the Indian region

Abstract

This paper is a case study of an unusual excursion of the subtropical jet stream into very low latitudes. From 18 December 1963, the subtropical jet stream began moving south from its normal position, roughly Bahrain to Delhi, consequent to the formation of a deep trough in the upper tropospheric westerlies, near Bahrain longitude. At 0000 GMT on 24 December 1963, the subtropical jet is located along Aden-Visakhapatnam, with Aden recording a maximum wind of 120 kms westerly, which is quite unusual. The vertical cross-section along longitude 80°E for 0000 GMT of 24 December 1963 shows clearly two jet stream9, the subtropical jet stream core near Visakhapatnam, below the tropical tropopause and close to a break in the tropopause and another jet stream core, over Delhi, in the angle formed by the tropopause and an inclined front which does not extend below 500 mb.