Development of new indices for the prediction of the West African climate

The dry climates of tropical Africa, especially during the Northern Hemisphere November-May, impose severe socio-economic consequences on a continent, which is a paradigm of global environmental change. Among the issues of prime concern, which has attracted attention from the international community, is the evolution of climate-sensitive, mutagenic, highly virulent serotypes of meningococcal meningitis such as serogroup W135, responsible for high fatalities and morbidities annually, affecting nearly 250,000 people, with an average of 25,000 deaths. With the pervasiveness of the disease, indexed by the meridional expansion of the “Meningitis Belt”, increase in risk factors, and hyperendemicity of the disease, its control is increasingly posing a major challenge to various governments in the sub-Saharan Africa. Recent studies have shown that there are strong relationships between the occurrence of meningitis and the atmospheric conditions during the dry season. For instance, some of the most important atmospheric conditions that trigger effective disease transmission are low humidity and long-range dust transport associated with the strong seasonal prevailing dry low-level northerlies emanating from the Sahara desert. Most prominent among meningitis-climate links is the high correlation between the end of the new cases of the disease and the beginning of the rainy season and in particular the onset of high levels of atmospheric humidity. Because of vaccine shortages this connection is now effectively being exploited in the planning of efficient preventive strategy and reactive vaccination campaigns. These strategies are achieved by administering the vaccines first to the most vulnerable populace based on the prediction (10-14 days) of areas where high humidity levels are not eminent. The effectiveness of the control, however, relies principally on two complementary program of actions, which entail the optimization of scarce allocation of vaccines and execution of orchestrated logistical planning, from regional to sector or district level, which are of course major constraints for the management of the disease in the endemic areas. On the seasonal time scale the health-climate linkage may be used to optimize the distribution of the vaccine, personnel and other related assets involved in the vaccination campaign. On even longer interannual time scales such foresight based on skillful climate prediction is important for the production of the vaccine which cannot be manufactured on short notice. The objective in the proposed research is to investigate both seasonal and interannual predictability of the West African dry season, focusing on the climatological parameters (e.g., atmospheric humidity levels, air temperature) and indicators derived from these primary climate variables to maximize correlation with the occurrence of meningitis. The study will involve the following specific tasks: (i) conduct statistical analyses to construct several coupled climate indices for meningitis, using the technique that will include single value decomposition (SVD) or maximum covariance analysis (MCA), which could be optimized for use as predictors. These will be expected to have stronger connections to the disease and more predictive skill than individual indices constructed by previous researchers. (ii). investigate the dominant climatologic modes of variability of the meningitis indices (using the techniques in (i)) and physical/dynamical mechanisms that modulate the temporal and spatial evolution of the proxy meningitis indicators, and (iii). use WRF model to downscale the 11 Global Producing Center (GPC) GCM forecasts by generating multi-model ensemble for dynamical prediction of the West African climates of the two timescales. Ultimately, the research will generate value-added products for use by agencies, organizations, policy-makers and end-users actively engaged in the vaccination campaign to enhance the disease control strategies to save lives in the subregion.