Monitoring High Altitude Aerosol Injections and Climate Impacts from a New Canadian Instrument Suite Concept (HAWC)

Abstract:

As interest in solar radiation management geoengineering through intentional injection of stratospheric aerosols continues to develop so does the necessity to monitor high-altitude aerosol emissions and their climatic impact. Although potential emission scenarios often require significant amounts (Tg) of aerosols, initial regional tests are unlikely to be at this scale, requiring measurement systems capable of early detection, and understanding of feedbacks on climate. A system capable of making these high-sensitivity and high-precision measurements is the High altitude Aerosols, Water vapour and Clouds (HAWC) system which is a suite of three Canadian instruments designed for space-based Earth observations, and proposed by Canada as part of the NASA A-CCP mission study. HAWC is composed of the Aerosol Limb Imager (ALI), Spatial Heterodyne Observation of Water (SHOW) and Thin Ice Clouds and Fire Infrared Emissions (TICFIRE). ALI and SHOW measure limb scattered sunlight, with vertical resolution of 500m, and long path lengths that provide excellent sensitivity to levels of aerosol and water vapour not possible from nadir mappers. Combined with the upwelling thermal radiation measurements from TICFIRE, the combination of instruments will allow for early detection of aerosol formation as well as important feedback mechanisms through water vapor and ice clouds. This work investigates the capability of the ALI instrument and retrievals to measure small amounts of aerosol injected in the UTLS. Further explored are the synergistic capabilities that HAWC provide in measuring and understanding aerosol-water-cloud interactions produced by small-to-moderate stratospheric injection geoengineering scenarios.