Using Satellite Nighttime Light to Measure Socio-Economic Activity in Africa Before and After COVID

Abstract

Using satellite nighttime light (NTL) data as a proxy to measure socio-economic activity in normal times has been well-established in the remote sensing literature. In the recent years, the NTL composites produced by the Visible Infrared Imaging Radiometer Suite (VIIRS) revealed a dimming of light in major cities during the COVID pandemic in large countries like China, India, and U.S. To test whether NTL remained a valid proxy of economic and human activity during upheaval times at the country level, this paper examined the association between NTL and GDP, CO2 emissions, and electricity consumption in all countries in Africa in the period of 2014-2021. The results indicated that NTL is associated with these three socio-economic indicators in a significant manner before and after the COVID pandemic. The model demonstrated high performance of NTL as a proxy for GDP and CO2 emissions in both periods while less so for electricity consumption (with R2=0.53, 0.48, 0.36, respectively, during pre-COVID period of 2014-19; and with R2=0.49, 0.45, 0.26, respectively, for 2014-2021 with COVID dummies). As NTL data are free and available at granular spatial and temporal levels for most areas on Earth with just a short time lag, the methodology offered an alternative to consistently measure economic and human activities and impact on the environment during normal times and after external shocks. This has the potential to fill data gaps, including for countries with weak capacity, and aid policy making to support sustainable green growth and provide information swiftly for post-disaster recovery.