Summary
Studies of all available upper wind data up to 3 km over eastern Africa and the western Indian Ocean reveal a major low-level air current circulating at about 1.5 km in the western periphery of the monsoon regime. The current originates in the southern hemisphere and penetrates progressively further north in spring until it reaches its maximum development in July. The major current is composed of systems of low-level jet streams which can be located on a daily basis, always in the same geographical areas, with speeds reaching 25–50 ms−1 at heights of only 1–1.5 km. Because the current is topographically-locked over eastern Africa the massive flow of air from one hemisphere to the other can be monitored and some relationships with the rainfall of parts of western India can be deduced.
This paper is only a brief review of the observational and analytical studies which have been carried out and reference should be made to original papers for details of the structure and development of the current.
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References
Anderson, D. L. T. (1976),The low level jet as a western boundary current, Monthly Weather Rev.,104, 907–921.
Brooks, C. E. P. andDurst, C. S. (1935),The circulation of air by day and night during the SW monsoon near Berbera, Somaliland, Quart. J. Roy. Met. Soc. Lond.61, 167.
Bunker, A. F. (1965),Interaction of the summer monsoon air with the Arabian Sea, Proceedings of the Symposium on Meteorological Results of I.I.O.E., Bombay, 22–26 July 1965. Poona, India Meteorological Department, pp. 3–16.
Cadet, D. (1977),Tropical disturbances as a relationship between the cross-equatorial flow over Kenya and rainfall over the western Indian coast (Paper submitted to the Quart. J. Roy. Met. Soc. Lond.).
Desai, B. N., Rangachari, N. andSubramanian, S. K. (1976),Structure of the low level jet stream over the Arabian Sea and the Peninsula as revealed by observations in June and July during the monsoon experiment (MONEX) 1973 and its probable origin, Ind. J. Met., Hydrol. Geophys.27, 263–274.
Findlater, J. (1966),Cross-equatorial jet streams at low level over Kenya, Meteorol. Mag., Lond.95, 353–364.
Findlater, J. (1967),Some further evidence of cross-equatorial jet streams at low level over Kenya, Meteorol. Mag. Lond.96, 216–219.
Findlater, J. (1969a),A major low level air current near the Indian Ocean during the northern summer, Quart. J. Roy. Met. Soc. Lond.95, 362–380.
Findlater, J. (1969b),Interhemispheric transport of air in the lower troposphere over the western Indian Ocean, Quart. J. Roy. Met. Soc. London.95, 400–403.
Findlater, J. (1971a),Mean monthly airflow at low levels over the western Indian Ocean, Geophysical Memoirs, Vol. XVI, No. 115 (HMSO, London).
Findlater, J. (1971b),The strange winds of Ras Asir, Meteorol. Mag., Lond.100, 46–54.
Findlater, J. (1972),Aerial explorations of the low-level cross-equatorial current over eastern Africa, Quart. J. Roy. Met. Soc. Lond.98, 274–289.
Findlater, J. (1974),An extreme wind speed in the low-level jet stream system of the western Indian OcIan, Meteorol. Mag. Lond.103, 201–205.
Findlater, J. (1977),A numerical index to monitor the Afro-Asian monsoon during the northern summers, Meteorol. Mag. Lond.106, 170–180.
Jambunathan, R. andRamamurthy, K. (1974),Wind field in the lower and middle troposphere over the Arabian Sea during the southwest monsoon of 1973, Ind. J. Met. Geophys.25, 400–410.
Joseph, P. V. andRaman, P. L. (1966),Existence of low level westerly jet streams over peninsular India during July, Ind. J. Met. Geophys.17, 407–410.
Meteorological Office,Pilot balloon observations made from H. M. Ships, 1925–36, Met. O. 431 (HMSO, London 1940).
Meteorological Office,Weather in the Indian Ocean, Vol. 2, Part 2, Met. O. 451b(2) (HMSO, London 1944).
Ramage, C. S. andRaman, C. R. V.,Meteorological Atlas of the IIOE, Part 2 (Upper Air) (University of Hawaii, Honolulu; National Science Foundation, Washington, D.C., 1972).
Ramsey, B. (1971),Surface winds at Mombasa, Kenya, Meteorol. Mag. Lond.100, 293–301.
Rome (1932–35),Ministero dell'Aeronautica, Annali dell' Ufficio Presagi. Vols. 4, 5, & 6.
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Findlater, J. Observational aspects of the low-level cross-equatorial jet stream of the western Indian Ocean. PAGEOPH 115, 1251–1262 (1977). https://doi.org/10.1007/BF00874408
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DOI: https://doi.org/10.1007/BF00874408