The Berkeley Environmental Air-quality and CO2 Network: Field calibrations of sensor temperature dependence and assessment of network scale CO2 accuracy

Abstract

The majority of global anthropogenic CO2 emissions originate in cities. We have proposed that dense networks are a strategy for tracking changes to the processes contributing to urban CO2 emissions and suggested that a network with g1/4g2gkm measurement spacing and g1/4g1gppm node-to-node precision would be effective at constraining point, line, and area sources within cities. Here, we report on an assessment of the accuracy of the Berkeley Environmental Air-quality and CO2 Network (BEACO2N) CO2 measurements over several years of deployment. We describe a new procedure for improving network accuracy that accounts for and corrects the temperature-dependent zero offset of the Vaisala CarboCap GMP343 CO2 sensors used. With this correction we show that a total error of 1.6gppm or less can be achieved for networks that have a calibrated reference location and 3.6gppm for networks without a calibrated reference.