Airborne detection of diffuse carbon dioxide emissions at Mammoth Mountain, California

Abstract
We report the first airborne detection of CO2degassing from diffuse volcanic sources. Airborne measurement of diffuse CO2degassing offers a rapid alternative for monitoring CO2emission rates at Mammoth Mountain. CO2concentrations, temperatures, and barometric pressures were measured at ∼2,500 GPS‐referenced locations during a one‐hour, eleven‐orbit survey of air around Mammoth Mountain at ∼3 km from the summit and altitudes of 2,895–3,657 m. A volcanic CO2anomaly 4–5 km across with CO2levels ∼1 ppm above background was revealed downwind of tree‐kill areas. It contained a 1‐km core with concentrations exceeding background by >3 ppm. Emission rates of ∼250 t d−1are indicated. Orographic winds may play a key role in transporting the diffusely degassed CO2upslope to elevations where it is lofted into the regional wind system.