Observing Volcanic Eruption Clouds in the UV at High Temporal Cadence with DSCOVR/EPIC

Volcanic emissions of sulfur dioxide (SO₂) and ash have been measured by ultraviolet (UV) sensors on polar-orbiting satellites for several decades, but such observations offer limited temporal resolution with typically only one overpass per day. This has restricted studies of key processes thought to occur during the initial few hours of atmospheric residence of volcanic eruption clouds. In 2015, the launch of the Earth Polychromatic Imaging Camera (EPIC) aboard the Deep Space Climate Observatory (DSCOVR) provided the first opportunity to observe volcanic eruption clouds from the first Earth-Sun Lagrange point (L1). The L1 vantage point provides continuous observations of the sunlit Earth disk, potentially offering up to a maximum of 8 or 9 observations of volcanic SO₂ and ash clouds in the EPIC field of view at 1 hour intervals. In June-July 2018, two eruptions in the Galápagos Islands (at Fernandina and Sierra Negra volcanoes) allowed us to verify this novel high-cadence capability of EPIC for the first time. We present EPIC observations of SO₂ emissions from these eruptions and several other recent volcanic eruptions from the tropics to mid-latitudes, and compare them to near-coincident SO₂ measurements from polar-orbiting hyperspectral UV and IR satellite instruments (OMI, OMPS, AIRS). The hourly cadence of DSCOVR/EPIC observations permits more timely measurements of SO₂ emissions by volcanic eruptions (important for assessing climate impact), improved trajectory modeling, and novel analyses of the temporal evolution of volcanic clouds.