Measuring wet deposition of organic carbon (OC) and black carbon (BC) is crucial for the complete understanding of the global circulation, lifetime, and radiative forcing of these aerosols. There is currently no accepted standard analytical method for measuring OC and BC concentration in precipitation. Different analytical methods have been employed for this purpose, but their feasibility has yet to be assessed. This manuscript evaluates the use of thermaloptical analysis (TOA), single-particle soot photometry (SP2), and ultraviolet-visible (UV/VIS) spectrophotometry for measuring BC in precipitation. In addition, total organic carbon (TOC) analysis was evaluated for the measurement of dissolved organic carbon (DOC) in precipitation. Potential interferences and sources of bias were assessed for each method. Precipitation samples and reference materials containing carbon particles generated from wood combustion and a natural gas diffusion flame were used in this study. The UV/VIS spectrophotometer, despite showing linearity with BC concentration, had inadequate sensitivity (±18 μg/L) to measure the low concentrations expected in precipitation. The SP2 analysis was adequate to measure refractory BC in precipitation in terms of precision and detection limit; however, systematic loss was estimated to be 34% (±3%). Sample filtration followed by TOA was inefficient for measuring particulate carbon in rainwater, as the quartz fiber filter captured less than 38% of the BC mass. Filtration was improved by adding salts and acids into the water samples, and ammonium dihydrogen phosphate, (NH 4 )H 2 PO 4 , was determined to be the best additive by increasing the collection efficiency of quartz fiber filters up to 95% (±5%). The TOC analyzer proved to be precise in the expected concentration range (200-5000 μg-C/L) for measuring DOC and total carbon (TC), including particulate OC and 94% (±2%) of the refractory BC in solution.
<p>Orbital remote sensing is the only tool allowing global, systematic monitoring of all 1500+ active volcanoes (based on the Smithsonian Holocene catalog). A specialized archive has been developed at the Jet Propulsion Laboratory: the ASTER Volcano Archive (AVA). AVA is comprised of over 200,000 ASTER frames spanning 20 years of the NASA&#8217;s Terra platform mission. The ASTER Volcano Archive (AVA: http://ava.jpl.nasa.gov) is the world's largest (at 100+Tb), and the only high spatial resolution (15-30-90m/pixel), multi-spectral (VNIR-SWIR-TIR), downloadable (kml enabled) dedicated archive of volcano imagery. The system is designed to facilitate parameter-based data mining, and for the implementation of archive-wide data analysis algorithms. Results include thermal anomaly detection and mapping, the temporal variability of individual volcanic emissions, as well as the detection of SO<sub>2</sub> plumes from both explosive eruptions and from passive emissions. A major expansion of the archive was implemented with the ingest of the full 1972-present Landsat dataset. In addition, the archive includes NASA Earth Observing-1 (EO-1) multispectral and hyperspectral imagery (10-30 m/pixel) of a subset of the Holocene catalog volcanoes obtained between 2004 and 2017. The newest version of AVA has been ported to the Amazon Web Services cloud and managed by the Jet Propulsion Laboratory&#8217;s Hybrid Science Data System (HySDS). This migration provides all of the previous capabilities, providing a stable, fast platform for rapid access to data. The system is updated with new data daily, with a latency of a few days following data acquisition. Currently we are developing a new user interface to facilitate easy, fast and efficient access to the archive. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology under contract to NASA. &#169; 2020 Caltech.</p>
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