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Modification of the structure of a tropical cyclone on traversing a high plateau
Author(s) -
Sellick N. P.
Publication year - 1958
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49708436107
Subject(s) - inflow , tropical cyclone , geology , precipitation , plateau (mathematics) , cyclone (programming language) , climatology , vortex , disturbance (geology) , atmosphere (unit) , circulation (fluid dynamics) , atmospheric circulation , atmospheric sciences , meteorology , oceanography , geography , physics , mechanics , geomorphology , mathematical analysis , mathematics , field programmable gate array , computer science , computer hardware
Apparent continuity is established between an Indian Ocean cyclone which reached the coast of southern Africa and a disturbance which traversed the continent from east to west. The surface structure of the disturbance is established from autographic records of its passage over the Rhodesias and Nyasaland. The pressure field is fitted to the ‘normal’ vortex of James (1950) and the upper winds observed are in fair accord. The surface observations indicate the presence of broad belts of northwest and southeast winds with a fairly abrupt transition but there is no evidence of fronts. Precipitation of the order of 50 mm per day is recorded over wide areas on several successive days. From consideration of the observed moisture content of the atmosphere it is inferred that an inflow of the order of 2 m/sec in the lowest layers is required to account for the precipitation. Elementary dynamic theory requires that such an inflow be accompanied by increasing circulation and deepening of the system. The depression, however, weakened and filled up slowly and it is shown that a reasonable allowance for turbulent and frictional losses would account for this.