SAGE III ISS Aerosol Measurements in the Context of Contemporaneous Satellite Observations

The satellite-based remote sensing community has numerous high frequency measurements ranging from Earth-viewing imagers and radiometers to limb scattering and emission measurements. For potentially transient and rapidly evolving atmospheric events involving newly injected aerosol most commonly associated with volcanism, the quantity of observations is important for capturing the vertical, horizontal, and temporal evolution of nascent aerosol. In contrast, the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station (ISS) observes occultation of either the Sun or the Moon by the atmosphere. Measurements are limited to a minimum of thirty-two retrievals daily during sunrise and sunset events as observed from ISS with additional observations as moonrises and moonsets are available. A third, limb scattering mode is additionally available from SAGE III ISS, but is outside of the scope of this presentation. SAGE III ISS is capable of measuring vertical profiles of atmospheric species including O₃, NO₂, water vapor, and aerosol with an instantaneous field-of-view of less than 0.5 km at the tangent point. The SAGE series of instruments has historically provided highly precise, accurate, and stable measurements founded upon the solar occultation technique and high signal-to-noise ratio offered by the Sun as a radiant target. While other instruments may offer higher temporal and horizontal sampling than SAGE III ISS, the SAGE measurement technique is a direct measurement of atmospheric transmission and is fundamental to the assumptions required in those other retrieval techniques. In its two and a half years in orbit SAGE has observed a number of atmospheric aerosol loading events including pyrocumulus and volcanic injections into the stratosphere. When combined with these higher temporally and horizontally resolved measurements the SAGE III ISS measurement offers an opportunity for a jointly derived context within varied landscape of satellite-based remote sensing techniques. This presentation will illustrate the synthesized understanding that can be gained when fusing retrievals from SAGE III ISS with other coincident satellite-based remote sensing observations. When viewed jointly, a better understanding of the impacts of atmospheric dynamics, local variability, and the characterization of the temporospatial state around a given observation can be gained.