Volcanogenic SO2 is an important source of climate forcing aerosols in the upper troposphere and a large unknown in global climate models. We intend to expand upon the techniques developed during our previously funded ESS research project (Development of a multi-species retrieval for quantifying volcanic emissions using MODIS, ASTER and AIRS, grant number: YNNG04GJ67G). We now have a suite of algorithms that can not only map SO2 at several spatial scales, but are being developed to correct for the presence of coexisting silicate ash and ice particles also found, particularly in explosively-derived contributions. MODIS, ASTER and AIRS are a perfect complement to each other as they operate at different spatial, spectral and temporal resolutions, facilitating quantification of the global SO2 budget sourced from a variety of eruptive styles.
We are proposing to address three interrelated science objectives; (1) global quantification of volcanogenic SO2; (2) and comparison of the infrared (IR) sensors to determine retrieval limits and (3) validation with spectrally independent, ultraviolet (UV) ground-based SO2 measurements. Contemporaneous imagery will be used to determine the effects of the varying instrumental parameters and differing retrieval schemes upon the detectability of SO2 for the various IR sensors. Robust new monitoring technologies will be applied to the issue of ground-truthing, specifically a UV imaging camera and mini-DOAS instruments. The camera has been extensively field and lab tested and has the ability to acquire similar imagery to that derived from satellites and has the potential to be an powerful validation tool.
This research addresses several key objectives in the context of the NRA, the Earth Science Research Program (ESRP) and NASA's overall remit. Within the NRA is the requirement of well-calibrated, multiyear, multisatellite data series to address a mission for measurements objective. The specific science objective, to quantify the amount of climatologically active SO2 injected in the atmospheric, serves as the driver for this research, which in some way addresses all five of the ESRP questions on atmospheric composition. The proposal sits at the heart of NASA's science directorate mission 'exploring the Earth, moon, Mars and beyond; charting the best route of discovery; and reaping the benefits of Earth and space exploration for society'.
