Africa: Modelling the southeast African regional climate
Southeastern Africa is a region with a population of ~270 million people who are strongly affected by the local climate. Hence, it is important to get a better understanding of the regional climate, how it has changed in the past, and how it is likely to change in the future. An important question is whether and how the rainfall over southeastern Africa responds to anthropogenic forcings as well as natural climate variability. Dominant atmospheric phenomena in this region include the intertropical convergence zone (ITCZ), the tropical monsoon and El Niño-Southern Oscillation (ENSO). Furthermore, it is important to revise and update climate knowledge based on local climate scientists. There is already scientific literature on climate change studies for southern Africa, but work remains in evaluating the model projections and calibrating their output with in-situ observations. Southeastern Africa is experiencing a climate change where trends in mean precipitation may be due to changes in the occurrence of rainy days or rain intensity. It is important to understand the causes of these trends. Likewise, it is important to understand how the local temperature responds to changing large-scale conditions. Such questions can be explored through downscaling the southeast African regional climate from global climate models (GCMs) experiments in CORDEX – Africa. The research will involve analysis of local observations, reanalysis, historical and data from regional climate models (RCMs) and empirical-statistical downscaling (ESD) to study dependencies between large-scale conditions and local variability in the rain and temperature statistics. ESD and RCM simulations will be combined to provide reliable future projections, for instance, by using RCMs as pseudo-reality and the statistical models to emulate seasonally aggregated high-resolution RCM output for a large ensemble of multi-model ensembles (CMIP). Local observations will also be used in the model evaluation to assess the added value of regional downscaling for both ESD and RCMs. The proposed Flagship Pilot Study (FPS) is tailored to investigate the connections between changes and trends, and special attention will be on the rainy season(s) and its/their duration. Identified dependencies will be utilised for making reliable future projections (ESD). The proposed study will also enable an investigation into the importance of regional scale forcings (aerosols, land-use change, vegetation etc) for the southeast African region. The results will be presented as aggregated statistics for daily temperature and precipitation together with assessments of the models.