Climate process chains: Examples from southern Africa

Abstract

The climate system comprises multiple components, primarily the atmosphere, ocean and cryosphere, each incorporating physical processes that interact across scales. To help understand the behaviour of this complex system, and evaluate climate model simulations, researchers typically take a reductionist approach, focusing on individual climate processes and studying their relationships with weather and climate in different regions. While more holistic approaches, such as climate networks, have been developed to explicitly address the complexity of the climate, here we argue for the use of a new approach that accounts for multiple cross‐scale process interactions, framed with respect to specific climate outcomes of societal importance. We introduce and explore the concept of “climate process chains” (CPCs), describing their potential application using examples determined for southern Africa. Building on related theoretical concepts, and through reviewing literature on climate processes and teleconnections to southern Africa, we identify candidate CPCs for two outcomes of societal interest; a regional‐scale drought and local‐scale heavy rainfall. Focusing on such outcomes means that CPC investigations have more relevance to climate risk management contexts, as well as providing a constraint on the exploration of climate uncertainties for a region. We argue that CPCs may help to articulate relationships amongst regionally relevant climate processes across temporal and spatial scales, and discuss their potential utility in climate research, including in the evaluation of climate models and their simulations.

Precipitation over southern Africa: is there consensus among global climate models (GCMs), regional climate models (RCMs) and observational data?

“…More specifically, the reason why we chose to put an emphasis on the AL pressure system is that the AL redistributes low-tropospheric moisture entering SAF from the southern Atlantic and the southern Indian oceans and also moisture transport originating from the Congo basin. In addition, AL events precede the formation of tropical temperate troughs (TTTs) and hence, they can be considered as their precursor in the "climate process chain" (Daron et al, 2019). As stated in Howard and Washington (2018), it is common that AL events precede TTT events, since the AL pressure system functions as a key process necessary for the transport of water vapor from the tropics towards the extratropics (Hart et al, 2010).…”

A simple set of indices describing the Tropical Rain Belt over central and southern Africa

“…In addition, the methodology can be applied to the precipitation climatology instead of (mm day −1 ) F I G U R E 5 Climatological annual cycle of the TRB indices for GPCC (blue), CRU (green), UDEL (red), ERAINT (black) and ERA5 (dark orange) monthly means that also helps to reduce noise, although provides less details (e.g., no interannual variability). The TRB indices have already been used to describe climate process chains (Daron et al, 2019) and to assess the cobehaviour of climate processes over southern Africa (Quagraine et al, 2019).…”

Influence of Climate on Conflicts and Migrations in Southern Africa in the 19th and Early 20th Centuries

“…In addition to a complex landscape that consists of steep slopes and latitudinal positioning, the climate of Southern Africa is influenced by combinations of oceanic and continental interactions that include the Mozambique channel trough, Mascarene high, southern annular mode, South Indian Ocean dipole, South Atlantic Ocean dipole, intertropical convergence zone, and ENSO [27][28][29][30][31][32][33]. Of these, ENSO plays a very critical role in influencing the climate variability in the region [34].…”