This study quantifies the air volume injected into the stratosphere by overshooting convection detected by GOES-16/17 geostationary infrared imagery and NOAA NEXRAD precipitation echo top during the 2021 and 2022 Dynamics and Chemistry of the Summer Stratosphere (DCOTSS) missions. This analysis seeks to address a key DCOTSS science question, namely “How much tropospheric air and water is irreversibly injected into the stratosphere by convection?” A novel method for defining individual storms or a cluster of adjacent storms as objects and tracking them throughout their lifetime facilitates the analysis. Overshooting convection injected 2,178,154 - 5,360,162 km3 of air into the stratosphere in 2021 and 6,017,486 – 10,642,008 km3 in 2022 over the North American study domain with GOES being higher than GridRad during both years. GOES overshooting detections were more uncertain due to difficulty differentiating updrafts from adjacent broad areas of cold outflow. Overshooting volume from the top 10 storm objects each year contributed 37 to 52% of the total domain wide volume. Total object-lifetime volume from these top 10 events ranged from ~90,000-790,000 km3 for GOES and ~49,000-560,000 km3 for GridRad. It was found that overshooting seldomly exceeded 5% of the total anvil area, demonstrating that very small regions within convection are responsible for impacting stratosphere composition. Despite differences in overshooting characteristics by the two sensors, airmasses initiated from GOES and NEXRAD overshooting and advected forward in time had similar spatial and vertical distributions, indicating that geostationary satellite data could be used to study the long-range transport of overshooting airmasses.

Uncertainty in Arctic top-of-atmosphere (TOA) radiative flux observations stems from the low sun angles and the heterogeneous scenes. Advancing our understanding of the Arctic climate system requires improved TOA radiative fluxes. We compare Cloud and Earth’s Radiant Energy System (CERES) TOA radiative fluxes with Arctic Radiation-IceBridge Sea and Ice Experiment (ARISE) airborne measurements using two approaches: grid box averages and instantaneously-matched footprints. Both approaches indicate excellent agreement in the longwave and good agreement in the shortwave, within 2 uncertainty considering all error sources (CERES and airborne radiometer calibration, inversion, and sampling). While the SW differences are within 2 uncertainty, both approaches show a ~‑10 W m‑2 average CERES-aircraft flux difference. Investigating the source of this negative difference, we find a substantial sensitivity of the flux differences to the sea ice concentration dataset. Switching from imager-based to passive microwave-based sea ice data in the CERES inversion process reduces the differences in the grid box average fluxes and in the sea ice partly cloudy scene anisotropy in the matched footprints. In the long-term, more accurate sea ice concentration data are needed to reduce CERES TOA SW flux uncertainties. Switching from imager to passive microwave sea ice data, in the short-term, could improve CERES TOA SW fluxes in polar regions, additional testing is required. Our analysis indicates that calibration and sampling uncertainty limit the ability to place strong constraints (<±7%) on CERES TOA fluxes with aircraft measurements.