schematic of southern African climate

Schematic of southern African climate, by Neil Hart/Creative Commons

Emma Howard, Amy Creese and Callum Munday each have a paper on early release in the highly rated Journal of Climate.

The three papers emerge from research associated with the NERC/DFID funded project UMFULA which focuses on central and southern African climate. The three papers follow closely on a fourth paper in Journal of Climate, led by Neil Hart, published in March 2018 - also as part of the UMFULA project.

UMFULA aims to tackle the uncertainty in climate model projections by filling critical gaps in our understanding of the fundamental climate science and by assessing regional projections of climate change from coupled climate models. The approach taken in UMFULA is to understand the processes by which the models simulate rainfall in order to establish the credibility of the climate change projections.

Emma Howard's paper unpicks the dynamics and thermodynamics of the Angola Low, a critically understudied piece of the jigsaw which organises austral summer rains at the southern edge of African tropical convection. Her work has diagnosed reasons that the Angola Low seems anchored in position east of the Atlantic coast and may well be important for explaining the hyper-aridity of the Namib Desert.

Callum Munday's contribution explores the climate processes in coupled climate models - the prime tool for climate prediction - with the aim of assessing the reliability of the models and highlighting important areas for model development. The paper shows that high precipitation rates in models which are too wet over southern Africa are associated with an anomalous northeasterly moisture transport which penetrates across the high topography of Tanzania and Malawi and into subtropical southern Africa. Coarse resolution climate models have a poor representation of topography which allows for the excessive moisture transport over that high ground.

In the third paper, Amy Creese shows how Congo Basin September-November rainfall varies by up to a factor of three across the set of coupled models used for climate prediction. In the case of the Congo Basin, the severe lack of observational data makes model evaluation difficult using standard techniques. This study uses a process-based assessment to evaluate the plausibility of mechanisms related to coupled model rainfall in September-November. Models tend to simulate a rainfall maximum in either the west or east of the basin. The assessment casts doubt on the credibility of models which are very wet in the west of the Congo Basin and have a large Atlantic SST bias.