A new database of the Entomological Inoculation Rate (EIR) is used to directly link the risk of infectious mosquito bites to climate in Sub-Saharan Africa. Applying a statistical mixed model framework to high-quality monthly EIR measurements collected from field campaigns in Sub-Saharan Africa, we analyzed the impact of rainfall and temperature seasonality on EIR seasonality and determined important climate drivers of malaria seasonality across varied climate settings in the region. We observed that seasonal malaria transmission requires a temperature window of 15-40 degrees Celsius and is sustained if average temperature is well above the minimum or below the maximum temperature threshold. Our study also observed that monthly maximum rainfall for seasonal malaria transmission should not exceed 600 mm in west Central Africa, and 400 mm in the Sahel, Guinea Savannah and East Africa. Based on a multi-regression model approach, rainfall and temperature seasonality were significantly associated with malaria seasonality in most parts of Sub-Saharan Africa except in west Central Africa. However, areas characterized by significant elevations such as East Africa, topography has a significant influence on which climate variable is an important determinant of malaria seasonality. Malaria seasonality lags behind rainfall seasonality only at markedly seasonal rainfall areas such as Sahel and East Africa; elsewhere, malaria transmission is year-round. The study’s outcome is important for the improvement and validation of weather-driven dynamical malaria models that directly simulate EIR. It can contribute to the development of malaria models fit-for-purpose to support health decision-making towards malaria control or elimination in Sub-Saharan Africa.

The presence, spatial extent and persistence of low-level clouds (LLCs) largely impact on the diurnal surface radiation and energy balance, as well as, the regional climate. Notwithstanding, there is limited understanding on their evolution and processes, particularly in southern West Africa. This paper assesses the development of LLCs and their dominant formative factors, as well as, their relationship with radiation and energy balance. Firstly, ceilometer and radiosondes deployed during the DACCIWA (Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa) field campaign were used in identifying the LLC. Afterwards, the cloud fraction was employed to characterize different LLC phases. Averagely, break-up, dissipation and build-up of LLC were marked at 0900 GMT, 1200 GMT and 2200 GMT respectively. Moreover, composites of LLC diurnal evolution and their relationship with net radiation, energy storage and surface stability showed that LLCs significantly impact on net radiation flux, by reducing downwelling shortwave radiation. Additionally, LLC onsets were characterized by a near-steady state in net radiation flux, whereas the rate of energy storage within the lower layers marginally oscillated about equilibrium. Finally, with observations from selected intensive observation periods (IOPs), the dominant factors influencing LLC development were evaluated. Horizontal cold air advection, with enhancement by nocturnal low-level jets, was observed to primarily influence the development of LLCs for the study period. Findings of this paper are necessary for improving the understanding of LLC characteristics, formation and interactions with surface properties, particularly over southern West Africa.

Agro-climatic zones are geographical areas delineated based on climate homogeneity and impact on agriculture. Ghana's agro-climatic zones have been in use since the 1960s, with no consideration given to current climate change and variability. The continued use of this age-old classified zones suggest Ghana's climate remains stable despite previous research findings to the contrary. In this study, we reconstructed a more appropriate and dis-aggregated agro-climatic zone map of Ghana that is in tandem with the current climate change and variability. Our findings revealed significant changes in the number of climate zones, their boundary sizes and geographical orientation. The newly proposed agro-climatic zones map consist of five distinctive climate regimes namely Sudan Savannah, Guinea Savannah, Transition, Forest and Coastal zones. The Sudan and Guinea Savannah zones showed a southerly expansion. The transition zone shriveled in size as the Guinea Savannah zone took over most of it, notably in the southeast. The forest zone also shrank in size with a northwest shift while the coastal belt grew to encompass the whole coast of Ghana. These changes are strong evidence of climate change and possible food production changes. The findings of this study are useful to agriculture sector in planning their activities, the health sector in predicting specific diseases caused by changes in weather and climate, Ghana Meteorological Agency for weather forecasting purposes, and the National Disaster Management in identifying disaster prone zones.