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

Abstract

Understanding the variability of the Tropical Rain Belt (TRB) in Africa is a challenging task due to complex interactions among global, regional and local drivers of rainfall. A simple method that provides a set of three indices describing large‐scale spatial–temporal characteristics of the TRB over central and southern Africa is introduced. The method is based on approximation of a meridional cross‐section of monthly mean precipitation by the Gaussian function. The three parameters of the Gaussian function correspond to the three TRB indices, namely: intensity, location and width. It is shown how the TRB indices can be used for describing the climatology of the TRB, for estimating observational uncertainties, and for evaluating the ERA‐Interim and ERA5 reanalyses against observations. Simplicity and flexibility of the method allow using the TRB indices for a wide range of applications, including evaluation of climate models and assessment of projected climate change in tropical rainfall.

Weather, Vol. 77, no. 6, April 2022, pp. 194–228

“…However, previous generations of climate models have shown significant problems with fundamental aspects of TRB seasonality, particularly over East Africa (Tierney et al, 2015). This group applied the TRB detection algorithm of Nikulin and Hewitson (2019) to CMIP6 data and then used it to evaluate TRB intensity, position and width in both historical and future projections as well as decadal predictions from the Decadal Climate Prediction Project. Results showed a northward shift in the rain belt during boreal summer and the intensity of the TRB was projected to increase across nearly all models.…”

The Bristol CMIP6 Data Hackathon

“…However, previous generations of climate models have shown significant problems with fundamental aspects of TRB seasonality, particularly over East Africa (Tierney et al ., 2015). This group applied the TRB detection algorithm of Nikulin and Hewitson (2019) to CMIP6 data and then used it to evaluate TRB intensity, position and width in both historical and future projections as well as decadal predictions from the Decadal Climate Prediction Project. Results showed a northward shift in the rain belt during boreal summer and the intensity of the TRB was projected to increase across nearly all models.…”