Summary
The largest part of Kenya exhibits two major rainy seasons, the March–May «long rains» and the October–December «short rains», both related to the passage of the ITCZ, but differing in the amount of rainfall recorded and its interannual variability. In order to investigate whether these differences also apply at intraseasonal time-scales, daily rainfall data for the peak month of each rainy season (April and November) were collected for 7 consecutive years (1982–1988). The network comprises 68 stations, from which a classification of the spatial patterns of daily rainfall anomalies has been performed. Wind anomalies corresponding to the various rainfall types and to specific regional rainfall departures were determined using four pilot balloon stations and one radiosonde station. They revealed that there exist significant differences between upper-air circulation anomalies exhibited in the «long» and «short» rainy seasons, especially as far as rain spells in the Eastern Highlands are concerned. In that region, easterly anomalies in the «short rains» period are associated with an increase in rainfall. During the «long rains», enhanced easterlies more generally coincide with an overall drop of convection in the country. In Western Kenya, wet conditions are more systematically associated to westerly wind anomalies.
Similar content being viewed by others
References
Agumba, F. O., 1985: Fluctuations of long rains in Kenya in relation to large scale circulations. KMD Research Report n° 1/85, 27 pp.
Alusa, A. L., Gwage, P. M., 1978 : The occurrence of dry spells during the East African long rains. KMD Research Report n° 2/78.
Anyamba, E. K., 1983: On the monthly mean lower tropospheric circulation, and the anomalous circulation during the 1961/62 floods in East Africa. M.Sc. thesis, University of Nairobi. 240 pp.
Bärring, L., 1988: Regionalization of daily rainfall in Kenya by means of common factor analysis.J. Climatol. 8, 371–389.
Beltrando, G., 1990: Space-time variability of rainfall in April and October–November over East Africa during the period 1932–1983.Int. J. Climatol. 10, 691–702.
Camberlin, P., 1994: Les précipitations dans la Corne orientale de l'Afrique: climatologie, variabilité et connexions avec quelques indicateurs océano-atmosphériques. Ph.D. thesis, Université de Dijon, France. 379 pp.
Camberlin, P., 1996: Intraseasonal variations of June–September rainfall and upper-air circulation over Kenya.Theor. Appl. Climatol. 54, 107–116.
Davis, T. D., Vincent, C. E., Beresford, A. K. C., 1985: July–August rainfall in West-Central Kenya.J. Climatol. 5, 17–33.
Hastenrath, S., Lamb, P. J., 1979:Climatic Atlas of the Indian Ocean Part 1: Surface Climate and Atmospheric Circulation. Madison: The University of Wisconsin Press, 116 pp.
Hastenrath, S., Nicklis, A., Greischar, L., 1993: Atmospheric-hydrospheric mechanisms of climate anomalies in the Western Equatorial Indian Ocean.J. Geophys. Res. 98 (C11), 20219–20235.
Hills, R. C., 1979: The structure of the Inter-Tropical Convergence Zone in Equatorial Africa and its relationship to East African rainfall.J. Inst. Brit. Geogr. 4–3, 329–352.
Jaetzold, R., Schmidt, H., 1983:Farm Management Handbook of Kenya. Nairobi: Ministry of Agriculture, 3 Volumes.
Johnson, D. H., Mörth, H.T, 1960: Forecasting research in East Africa. Proc. of the symposium on Tropical Meteorology in Africa. Nairobi, Kenya: WMO/Munitalp Foundation. 56–132.
Minja, W. S. M., 1987: The weather anomalies over Africa during the drought year 1972 and the floods of April 1977 over parts of Eastern Africa. Proceed. 1st Tech. Conf. Meteo. Research in Eastern and Southern Africa. KMD, Nairobi, 6–9 Jan. 1987, 99–101.
Nyenzi, B. S., 1988a: Mechanisms of East African rainfall variability. Ph.D. thesis, Florida State University, Tallahassee, U.S.A 184 pp.
Nyenzi, B. S., 1988b: Equatorial zonally moving disturbances which contributed to the East African long rains of March to May 1979., InWAMEX related research and tropical meteorology in Africa. WMO, TMRP, n° 28, 270–271.
Odingo, R. S., 1971:The Kenya Highlands. Nairobi: East African Publishing House, 229 pp.
Ogallo, L. J., 1988: Climatology of rainfall in East Africa. InWAMEX related research and tropical meteorology in Africa. WMO, TMRP, n° 28, 136–142.
Ogallo, L. J., Jonawiak, J. E., Halpert, M. S., 1988: Teleconnection between seasonal rainfall over East Africa and global sea-surface temperature anomalies.J. Meteor. Soc. Japan. Ser.11, 66-6. 807–822.
Ogallo, L. J., Anyamba, E. K.,1985: Drought of tropical central and eastern Africa. Proc. WMO Symposium on Medium and Long Range Forecasting. Maryland, USA WMO/TD n° 87, 67–72.
Richman, M. B., Lamb, P. J., 1985: Climate pattern analysis of three and seven-day summer rainfall in central United States: some methodological considerations and a regionalization.J. Climate Appl. Meteor. 24, 1325–1343.
Rowell, D. P., Ininda, J. M., Ward, M. N., 1994: The impact of sea surface temperature patterns on seasonal rainfall in East Africa. Proc. Int. Conf. on Monsoon Variability. Trieste, Italie. WMO/TD n°619. 666–672.
Sissons, J., 1966: Some examples of synoptic situations which affect East Africa.Weather 21, 228–231; 260–262; 298–300.
Sumner, G. N., 1982: Rainfall and wind circulation in Coastal Tanzania.Arch. Met. Geoph. Biokl., Ser. B 30, 107–125.
Tomsett, J. E., 1969: Average monthly and annual rainfall maps of East Africa. EAMD Tech. Memo., n° 14.
Wairoto, J. G., Nyenzi, B. S., 1987: The unseasonal heavy rains in Kenya during January 1979. Proceed. 1st Tech. Conf. Meteor. Research in Eastern and Southern Africa. KMD. Nairobi, 6–9 Jan. 1987, 173–178.
Wairoto, J. G., Bundi, P. M., 1993: Temporal and spatial characteristics of rainfall during October 1978 to January 1979 in Kenya. Proceedings of the First Intern. Conf. of African Meteor. Society, Nairobi, 8–12 Febr. 1993. 553–564.
Ward, J. H., 1963: Hierarchical grouping to optimize an objective function.J. American Statist. Association 58, 236–244.
Author information
Authors and Affiliations
Additional information
With 12 Figures
Rights and permissions
About this article
Cite this article
Camberlin, P., Wairoto, J.G. Intraseasonal wind anomalies related to wet and dry spells during the “long” and “short” rainy seasons in Kenya. Theor Appl Climatol 58, 57–69 (1997). https://doi.org/10.1007/BF00867432
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00867432