Role of gas flaring from Russia's oil and gas production in triggering high black carbon episodes over the Arctic

Black carbon plays a unique role in the Arctic climate system due to its multiple climatic effects. As the country that flares the largest quantity of associated petroleum gas, Russia’s gas flaring emissions have been rarely evaluated especially for black carbon emission due to incomplete combustion. In this study, we reconstruct BC emissions for Russian Federation, which is the country that has the largest area in the Arctic Circle. In 2010, total anthropogenic BC emission of Russia is estimated to be around 224 Gg. Gas flaring, a commonly ignored black carbon source, contributes a dominant 36.2% of Russia’s total anthropogenic BC emissions. BC simulations are conducted using the hemispheric version of CMAQ with emission inputs from a global emissions database EDGAR -HTAPv2 and EDGAR-HTAPv2 with its Russian part replaced by the newly developed Russian BC emissions, respectively. At the four ground monitoring sites (Zeppelin, Barrow, Alert, and Tiksi) in the Arctic Circle, surface BC simulations are improved the most during the Arctic haze periods (October - March). By investigating the Zeppelin site, it is found that the gas flaring emission is the crucial source for triggering the high BC episodes during the spring Arctic haze period. Gas flaring from Russia contributes an increasing fraction as the measured BC concentrations at Zeppelin increase. Above 85% percentile of the measured BC concentrations, gas flaring could explain over 50% of them. This study demonstrates the good capability of H-CMAQ in simulating the transport of BC particles to the Arctic and suggests that the impact of Russian flaring emissions on the Arctic haze has likely been underestimated, which is one of the causes that previous modeling works struggled in reproducing the BC levels in the Arctic region.