Carbon Dioxide Emissions During the 2018 Kilauea Volcano Eruption Estimated Using OCO‐2 Satellite Retrievals

This study applies Orbiting Carbon Observatory‐2 (OCO‐2) column‐averaged dry‐air mole fractions of CO 2 (XCO 2 ) to constrain CO 2 fluxes during the 2018 Kilauea volcano eruption. CO 2 enhancements (ΔXCO 2 ) of 1–2 parts per million were observed far downwind of the eruption coincident with elevated sulfur dioxide (SO 2 ) concentrations. The estimated CO 2 emission rate was 77.1 ± 49.6 kilotons per day (kt day −1 ) on 11 July 2018 with most of the uncertainty from modeled winds and XCO 2 retrievals. This emission rate is higher compared to flux estimates made with ground‐based measurements (30–40 kt day −1 ). However, cross‐sectional flux estimates made using OCO‐2 XCO 2 observations will inherently be larger than ground‐based measurements near the source as these estimates comprise all sources of CO 2 in the vicinity of the eruption (e.g., vegetation and soil burning). This study for the first time uses satellite XCO 2 data ~200 km downwind to estimate CO 2 emissions from a major volcanic eruption.