157Fig. 4.6 Population and night lights, global. Maps of population and night lights interpolated to
the same 0.125° × 0.125° (latitude, longitude) grid. (a) Population density for 2015 obtained from
the NASA SEDAC GPWv4 dataset; (b) night lights measured by the Suomi NPP VIIRS DNB
radiometer for cloud free scenes, averaged over all of 2015. The VIIRS night lights data have been
processed to remove the dominant effects of aurora borealis and fires. A logarithmic color scale has
been used for both population and night lights, to better display the dynamic range of both quanti-
ties. Population density is shown in units of people per square kilometer (ppl km−^2 ) and night lights
are expressed in units of 10−^9 watts per square cm per steradian (nW cm−^2 sr−^1 ). See Methods for
further information
4.3 Economic Disparity