References seasonal forecasting
- Dalu, G.A. M. Gaetani, R.A. Pielke Sr., M. Baldi, and G. Maracchi, 2005: Regional variability of the ITCZ and of the Hadley cell. Int. J. Climatol., submitted.
- Fontaine B., Janicot S., 1996: Sea surface temperature fields associated with West African rainfall anomaly types. J. Climate, 9, 2935-2940.
- Giannini A., Saravanan R., Chang P., 2003: Oceanic forcing of Sahel rainfall on interannual to interdecadal time scales. Science, vol. 302, 1027-1030.
- Huffman, G. J. and co-authors, 1997: The Global Precipitation Climatology Project (GPCP) combined data set. Bull. Am. Met. Soc., 78, 5-20.
- Kalnay E., and coauthors, 1996: The NCEP/NCAR 40-Year Reanalysis Project. Bull. Am. Met. Soc., 77, 437-471.
- Kistler R., E., and coauthors, 2001: The NCEP–NCAR 50-Year Reanalysis: Monthly Means CD-ROM and Documentation. Bull. Am. Met. Soc., 82, 247-268.
- Xie P., and Arkin P. A., 1996: Global precipitation: a 17-year monthly analysis based on gauge observations, satellite estimates, and numerical model outputs. Bull. Am. Met. Soc., 78, 2539-2558.
- Xie, P., Janowiak, J. E., Arkin, P. A., Adler, R., Gruber, A., Ferraro, R., Huffman, G. J., and S. Curtis, 2003: GPCP pentad precipitation analyses: an experimental dataset based on gauge observations and satellite estimates. J. Climate, 16, 2197-2214.
- Vizy E.K., Cook, K.H., 2001: Mechanics by which Gulf of Guinea and Eastern North Atlantic Sea Surface Temperature Anomalies can influence African Rainfall. J. Climate, 14, 795-821.
- Vizy E.K., Cook, K.H., 2002: Development and application of a mesoscale climate model for the tropics: Influence of sea surface temperature anomalies on the West African Monsoon. J. Geophys. Research, 107(D3), 10.1029/2001JD000686.
West Africa Monsoon Onset and Withdrawal methods.
Several empirical methods, mainly based on the rainfall, but on other variables too, have been developed in order to estimate the onset of the monsoon.
- Ilesanmi (1972) identify the onset and the retreat of the monsoon in Nigeria using prescribed percentiles of the cumulated rainfall. The onset occurs when the cumulated rainfall reaches 8% of total, and the withdrawal when the cumulated rainfall reaches 90% of the total.
Ilesanmi, O.O., 1972: An empirical formulation of the onset, advance and retreat of rainfall in Nigeria. J. Tropical Geography, 34, 17-34.
- Omotosho et al. (2000) use the equivalent potential temperature to predict the onset and cessation of the rainy season in Kano (12°N, 8°E, Nigeria).
Omotosho, J.B., A.A. Balogun, and K. Ogunjobi, 2000: Predicting monthly and seasonal rainfall, onset and cessation of the rainy season in the West Africa using only surface data. Int. J. Climatol., 20, 865-880.
- Sultan and Janicot (2003) distinguish the preonset from the onset phase: the preonset occurs in late spring when the intertropical convergence zone (ITCZ) reaches 5°N, while the actual onset occurs in late June when the ITCZ shifts northward up to 10°N. Climatologically this occurs on June 24, with a 8 days standard deviation. This shift occurs with a steep decrease of the rainfall in the Guinean region, followed by a steep increase in the Sudan-Sahel region.
Sultan, B., and S. Janicot, 2003: The West African Monsoon Dynamics. Part II: The “Preonset” and “Onset” of the Summer Monsoon. J. Climate, 16, 3407-3427.
- Louvet et al. (2003), using pentad rainfall data, identify the onset with the active phase after the third pause of the four pauses and active phases of the monsoon. Analyzing the period 1979-2001, they find that the climatological onset occurs on June 25 (36th pentad), with a standard deviation of 2 pentads.
Louvet, S., B. Fontaine, and P. Roucou, 2003: Active phases and pauses during the installation of the West Africa monsoon through 5-day CMAP rainfall data (1979-2001). Geophys. Res. Lett., 30 (24), 2271, doi:10.1029/2003GL018058.
- Odekunle et al. (2005) find the onset and retreat dates in Nigeria for the period 1962-1996, using a stepwise multiple linear regression analysis. Their analysis is based on four promoting factors: the sea surface temperature in the tropical Atlantic, the land-sea thermal contrast between the Atlantic and Nigeria, the position of the intertropical discontinuity (ITD), and the surface temperatures in selected Nigerian sites.
Odekunle, T.O., E.E. Balogun, and O.O. Ogunkoya, 2005: On the prediction of rainfall onset and retreat dates in Nigeria. Theor. Appl. Climatol., 81, 101-112.