Figure 1: Distributions of observed and modelled precipitation changes.
From: Local biomass burning is a dominant cause of the observed precipitation reduction in southern Africa
Trend in observed precipitation (mm month−1) over the June to September season (a), absolute precipitation changes (mm month−1) for the same season from observations and various model experiments (b–f), and relative precipitation changes (%) from observations and the CO2BB model experiment (g–h). Values in (a) are averaged over the subregion shown by the dashed rectangle in (b). Panels a,b and g are from observations (GPCC) whereas the five other panels are from models results, one with the regional WRF model (c) and four from the global CESM model (d–f,h). Model results are shown as differences from the BASE simulation and show differences between 2000 and 1850 conditions in each case; see text and Table 1 for notation of the experiments. Observed precipitation trends in (a) are shown for the whole GPCC time period from 1901 to 2010 (red) and from 1951 to 2010 (blue). Observations in (b) are shown as the difference 1981:2010−1901:1930 because 30-year averages are needed to reduce noise (that is, the influence of natural variability). Note that in most parts of the region, the number of stations per grid cell is low in the GPCC data. In plots (b–f), symbols denote grid boxes where changes are significant (P value <0.05) according to a two-tailed Student’s t-test (grey ‘+’ symbols), and when also accounting for multiple statistical testing according to ref. 54 (black ‘+’ symbols).
