E-WP5 - PROMISA: Processes evaluation of MiKlip decadal hindcasts over tropical Africa

Rain-fed agriculture is the main industry in tropical Africa, and plays a crucial role in sustaining livelihoods and economic development. However, the failure of seasonal rainfall and interannual to decadal precipitation fluctuations provokes droughts or flooding which lead to enormous impact on socio-economic activities over the region. Therefore, understanding of the mechanisms that produce this variability and developing both dynamical and statistical approaches for seasonal to decadal forecasts and climate projections are of great importance for policymaker and humanitarian aid agencies.

The MIKLIP-PROMISA (Process Evaluation of the MiKlip Decadal Forecast System in Tropical Africa) study areas are the West Africa Monsoon (WAM) and the Greater Horn of Africa (GHA) regions. Both regions show large interannual to decadal rainfall variations, the Sahel drought in the 1970s and 1980s (Rodríguez-Fonseca et al. 2015) and the failure of consecutive rainy seasons in GHA regions presents a major climatic shock to the region, as witnessed by the resulting humanitarian crisis in 2011 (FEWS NET, 2011).  Recent observational and modeling studies also indicated a drying trend of March-April-May rainfall, the “long rains” in parts of the GHA (Yang et al. 2014).  These interannual to decadal variations of rainfall over tropical Africa are often linked to sea surface temperatures anomalies in adjacent and remote ocean basins.

They are these well-established linkages that promise an exploitable potential of decadal forecast predictability in tropical Africa using state-of the art coupled Ocean-Atmosphere models. To validate the models and assess their forecast skill, both the calculation of statistical measures, like ensemble skill scores, and the evaluation of oceanic and atmospheric processes pertinent to rainfall variability are mandatory. One major aim of PROMISA is therefore to identify processes and teleconnections controlling seasonal to decadal variability and predictability in the WAM and GHA regions and add corresponding software plug-ins to MIKLIP’s Central Evaluation system. Subsequently, an intensive skill scores and process evaluation of potentially improved MiKlip II decadal hindcasts and experimental forecasts will be carried out with Max-Planck-Institute for Meteorology (MPI-fM) Earth system Model (ESM) and other similar hindcasts from other modeling centres.

Reference  

FEWS NET (2011), Past year one of the driest on record in the eastern Horn, Famine Early Warning System Network Report, June 14, 2011, U.S. Agency for International Development, Washington, D.C.

Yang, W., Seager, R., Cane, M. A., and Lyon, B.: The East African long rains in observations and models, J. Climate, 27, 7185–7202, 2014.

Rodríguez-Fonseca et al. 2015: Variability and predictability of West African droughts: A review of the role of sea surface temperature anomalies. J. Climate, 28, no. 10, 4034-4060, doi:10.1175/JCLI-D-14-00130.1.