Comparison of COSPEC and two miniature ultraviolet spectrometer systems for SO(2) measurements using scattered sunlight
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| Authors: | Elias, T; Sutton, AJ; Oppenheimer, C; Horton, KA; Garbeil, H; Tsanev, V; McGonigle, AJS; Williams-Jones, G |
| Year: | 2006 |
| Journal: | Bulletin of Volcanology 68: 313-322 Article Link (DOI) |
| Title: | Comparison of COSPEC and two miniature ultraviolet spectrometer systems for SO(2) measurements using scattered sunlight |
| Abstract: | The correlation spectrometer (COSPEC), the principal tool for remote measurements of volcanic SO(2), is rapidly being replaced by low-cost, miniature, ultraviolet (UV) spectrometers. We compared two of these new systems with a COSPEC by measuring SO(2) column amounts at Kilauea Volcano, Hawaii. The two systems, one calibrated using in-situ SO(2) cells, and the other using a calibrated laboratory reference spectrum, employ similar spectrometer hardware, but different foreoptics and spectral retrieval algorithms. Accuracy, signal-to-noise, retrieval parameters, and precision were investigated for the two configurations of new miniature spectrometer. Measurements included traverses beneath the plumes from the summit and east rift zone of Kilauea, and testing with calibration cells of known SO(2) concentration. The results obtained from the different methods were consistent with each other, with < 8% difference in estimated SO(2) column amounts up to 800 ppm m. A further comparison between the COSPEC and one of the miniature spectrometer configurations, the 'FLYSPEC', spans an eight month period and showed agreement of measured emission rates to within 10% for SO(2) column amounts up to 1,600 ppm m. The topic of measuring high SO(2) burdens accurately is addressed for the Kilauea measurements. In comparing the foreoptics, retrieval methods, and resultant implications for data quality, we aim to consolidate the various experiences to date, and improve the application and development of miniature spectrometer systems. |
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