LAUSR

This study applies Orbiting Carbon Observatory‐2 (OCO‐2) column‐averaged dry‐air mole fractions of CO2 (XCO2) to constrain CO2 fluxes during the 2018 Kilauea volcano eruption. CO2 enhancements (ΔXCO2) of 1–2 parts per million were observed far downwind of the eruption coincident with elevated sulfur dioxide (SO2) concentrations. The estimated CO2 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 XCO2 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 XCO2 observations will inherently be larger than ground‐based measurements near the source as these estimates comprise all sources of CO2 in the vicinity of the eruption (e.g., vegetation and soil burning). This study for the first time uses satellite XCO2 data ~200 km downwind to estimate CO2 emissions from a major volcanic eruption.