Figure 4 .
4Observational stations of selected networks and their relative density for (a) ground-based atmospheric and greenhouse gas, (b) ground-based meteorological and (c) oceanic observation on and around the African continent. More detailed information of the represented networks can be found in table 2 of the supplementary material. The heatmaps are based on kernel density estimations of all stations of the considered networks within a bounding box of 40 to −40 degrees latitude and −50 to 80 degrees longitude. Note that the operational status of each station has not been taken into account since this information was not available for all networks. The source for the station **data** for most of the networks is the WMO's OSCAR tool.
