Literature

Platt, U.; Stutz, J.

doi:10.1007/978-3-540-75776-4_13

Cited by 12 publications

(2 citation statements)

References 815 publications

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“…In each scan, 104 open‐path ultraviolet spectra are collected. SO 2 slant column densities are reduced from each spectrum following the Differential Optical Absorption Spectroscopy (DOAS) methodology [e.g., Platt and Stutz , 2008] using a modeled reference spectrum [ Salerno et al , 2009b]. SO 2 column densities are then transmitted by Free Wave radio‐modem to INGV‐CT, where SO 2 mass flux (in megagram per day, Mg d −1 ) is computed in real‐time.…”

Section: Methodsmentioning

confidence: 99%

An unloading foam model to constrain Etna's 11-13 January 2011 lava fountaining episode

et al. 2011

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[1] The 11-13 January 2011 eruptive episode at Etna volcano occurred after several months of increasing ash emissions from the summit craters, and was heralded by increasing SO 2 output, which peaked at ∼5000 megagrams/day several hours before the start of the eruptive activity. The eruptive episode began with a phase of Strombolian activity from a pit crater on the eastern flank of the SE-Crater. Explosions became more intense with time and eventually became transitional between Strombolian and fountaining, before moving into a lava fountaining phase. Fountaining was accompanied by lava output from the lower rim of the pit crater. Emplacement of the resulting lava flow field, as well as associated lava fountain-and Strombolian-phases, was tracked using a remote sensing network comprising both thermal and visible cameras. Thermal surveys completed once the eruptive episode had ended also allowed us to reconstruct the emplacement of the lava flow field. Using a high temporal resolution geostationary satellite data we were also able to construct a detailed record of the heat flux during the fountain-fed flow phase and its subsequent cooling. The dense rock volume of erupted lava obtained from the satellite data was 1.2 × 10 6 m 3 ; this was emplaced over a period of about 6 h to give a mean output rate of ∼55 m 3 s −1 . By comparison, geologic data allowed us to estimate dense rock volumes of ∼0.85 × 10 6 m 3 for the pyroclastics erupted during the lava fountain phase, and 0.84-1.7 × 10 6 m 3 for lavas erupted during the effusive phase, resulting in a total erupted dense rock volume of 1.7-2.5 × 10 6 m 3 and a mean output rate of 78-117 m 3 s −1 . The sequence of events and quantitative results presented here shed light on the shallow feeding system of the volcano.

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Section: Methodsmentioning

confidence: 99%

An unloading foam model to constrain Etna's 11-13 January 2011 lava fountaining episode

et al. 2011

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“…With the rapid industrial development and transportation, urban air pollution is worsening; the ecological balance and human health have being affected directly and seriously, so air pollution monitoring is considerable importance. Differential Optical Absorption Spectroscopy (DOAS) is nowadays widely used to derive trace gas abundances in the atmosphere, either from direct or scattered light observations [1][2][3][4]. DOAS uses the narrow molecular absorption bands to identify trace gases and their absorption strength to retrieve troposphere and stratospheric trace-gas concentrations [5].…”

Section: Introductionmentioning

confidence: 99%

Principal Component Regression Applied in Differential Optical Absorption Spectroscopy Measurement

Wei

Chen

2013

AMR

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Differential optical absorption spectroscopy (DOAS) is a well-established and widely used technique for monitoring atmospheric pollution. The month performance of a DOAS system was assessed at a certain place in Tianjin University, China, where is farther away from the industrial pollution a source. Three methods were used to inverse the hourly concentrations of nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3). Principal component analysis (PCA) was performed to analyze the retrieving concentrations. Results were obtained for estimated temporal NO, NO2, SO2, O3 distributions over the urban atmosphere; demonstrating the capability of the principal component analysis applied in differential optical absorption spectroscopy (PCA-DOAS) technique.

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Spatial and temporal variability of ozone sensitivity over China observed from the Ozone Monitoring Instrument

2015

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Surface ozone (O 3 ) air pollution in populated regions has been attributed to emissions of nitrogen oxides (NO + NO 2 = NO x ) and reactive volatile organic compounds (VOCs). These constituents react with hydrogen oxide radicals (OH + HO 2 = HO x ) in the presence of sunlight and heat to produce O 3 . The question of whether to reduce NO x emissions, VOC emissions, or both is complicated by spatially and temporally heterogeneous ozone-NO x -VOC sensitivity. This study characterizes spatial and temporal variations in O 3 sensitivity by analyzing the ratio of formaldehyde (HCHO, a marker of VOCs) to nitrogen dioxide (NO 2 ), a metric known as the formaldehyde nitrogen ratio (FNR). Level 3 gridded retrievals from the Ozone Monitoring Instrument (OMI) aboard the NASA Aura satellite were used to calculate FNR, with our analysis focusing on China. Based on previous studies, we take FNR < 1.0 as indicating VOC-limited regimes, FNR > 2.0 as indicating NO x -limited regime, and FNR between 1.0 and 2.0 as indicating transitional regime (where either NO x reductions or VOC reductions would be expected to reduce O 3 ). We find that the transitional regime is widespread over the North China Plain (NCP), the Yangtze River Delta, and the Pearl River Delta during the ozone season (defined as having near-surface air temperatures >20°C at the early afternoon OMI overpass time). Outside of these regions, the NO x -limited regime is dominant. Because HCHO and NO 2 have distinct seasonal patterns, FNR also has a pronounced seasonality, consistent with the seasonal cycle of surface O 3 . Examining trends from 2005 to 2013 indicates rapid growth in NO 2 , especially over less-developed areas where O 3 photochemistry is NO x limited. Over this time period, HCHO decreased in southern China, where VOC emissions are dominated by biogenic sources, but increased slightly over the NCP, where VOC emissions are dominated by anthropogenic sources. A linear regression approach suggests that most of China (70% of grid cells) will be characterized by a transitional regime during the O 3 season by 2030. However, in megacities such as Guangzhou, Shanghai, and Beijing, NO 2 has decreased such that the chemical regime has shifted from VOC limited in 2005 to transitional in 2013.

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Literature

Cited by 12 publications

References 815 publications

An unloading foam model to constrain Etna's 11-13 January 2011 lava fountaining episode

An unloading foam model to constrain Etna's 11-13 January 2011 lava fountaining episode

Principal Component Regression Applied in Differential Optical Absorption Spectroscopy Measurement

Spatial and temporal variability of ozone sensitivity over China observed from the Ozone Monitoring Instrument

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