A major focus of the lab has been documenting rainfall variability over Africa. We have focused on regional averages and have examined interdecadal variability. We have also examined various characteristics of the variability, such as the seasonal contribution to interannual variability, spatio-temporal patterns, seasonal and interannual persistence of anomalies, teleconnections and seasonal aspects of the teleconnections. The studies have focused on continental scales and on select regions, such as the Sahel, East Africa, and Botswana/Namibia. Most of the work relies on gauge data, but satellite estimates of rainfall have also been used. We are currently extending our data base to the most recent years and evaluating variability in other arid regions of the world, most notably the deserts of the Middle East, Australia and South America.
		2000: An Analysis of Recent Rainfall Conditions in West Africa, Including the Rainy Seasons of the 1997 El Niño and the 1998 La Niña Years (with B. Some and B. Kone). Journal of Climate, 13, 2628-2640. 1999: Sahel Drought in West Africa. Encyclopedia of Global Change (A. S. Goudie, ed.), Oxford University Press, New York, in press. 1998: Interannual and interdecadal variability of rainfall over the African continent during the last two centuries. In Water resources variability in Africa during the XXth Century (E. Servat, D. Hughes, J.-M;. Fritsch and M. Hulme, eds.), IAHS Press, Wallingford, UK, 107-116. 1996: Rainfall in the Sahel during 1994 (with M.B. Ba and J.Y. Kim) Journal of Climate, 9, July, 1673-1676. 1996: Africa. Encyclopedia of Climate and Weather (S.H. Schneider, ed.), Simon Schuster, New York, 13-19. 1995: Satellite-derived Interannual Variability of West African Rainfall 1983-88. Journal of Applied Meteorology (with M.B. Ba, R. Frouin), 34, 411-431. 1995: Variability of African rainfall on interannual and decadal time scales. Natural Climate Variability on Decade-to-Century Time Scales (Climate Research Committee, eds.), National Academy Press, Washington, D. C., 32-43. 1994: Recent rainfall fluctuations in Africa and their relationship to past conditions over the continent. The Holocene 4, 2, 121-131. 1993: An Overview of African Rainfall Fluctuations of the Last Decade. Journal of Climate, V6, 7. 1463-1466. 1993: A Re-Evaluation of Rainfall Variability in the Sahel. Part I. Characteristics of Rainfall Fluctuations. (with I.M. Palao). Int. Journal os Climatology, 13, 371-389. 1989: Long-term changes in African rainfall. Weather 44, 2, 47-56. 1989: African Drought: Characteristics, Causal Theories and Global Teleconnections. Understanding Climate Change (A. Berger, R.E. Dickinson and J.W. Kidson, ed.), American Geophysical Union, Washington, D.C., 79-100. 1986: The spatial coherence of African rainfall anomalies: Interhemispheric teleconnections. Journal of Climate and Applied Meteorology, 25, 1365-1381. 1986: The nature of rainfall variability in Africa south of the equator. Journal of Climatology, 6, 515-530. 1985: Sub-Saharan rainfall 1981: - 1984:. Journal of Climate and Applied Meteorology, 24, 1388-1391. 1983: Sub-Saharan Rainfall in the Years 1976-1980: Evidence of Continued Drought. Monthly Weather Review, 111, 8, 1646-1654. 1983: Recent Rainfall Fluctuations in Africa interhemispheric teleconnections. Variations in the Global Water Budget (A. Street-Perrott, M. Beran, R. Ratcliffe, eds.), Reidel, Dordrecht, 221-238 (S.E. Nicholson and R.M. Chervin). 1981: Rainfall and atmospheric circulation during drought periods and wetter years in West Africa. Monthly Weather Review, 109, 2191-2208. 1980: The nature of rainfall fluctuations in subtropical West Africa. Monthly Weather Review, 108, 473-487.  1979: Revised rainfall series for the West African subtropics. Monthly Weather Review, 107, 620-623.   1979: Statistical typing of rainfall anomalies in sub-Saharan Africa. Erdkunde, 33, 95-103.