scholarly journals Particle size distribution factor as an indicator for the impact of the Eyjafjallajökull ash plume at ground level in Augsburg, Germany

2011 ◽  
Vol 11 (6) ◽  
pp. 16417-16437 ◽  
Author(s):  
M. Pitz ◽  
J. Gu ◽  
J. Soentgen ◽  
A. Peters ◽  
J. Cyrys
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Long Range ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Size Range ◽  
Ground Level ◽  
Saharan Dust ◽  
Ash Plume ◽  
The Impact

Abstract. During the time period of the Eyjafjallajökull volcano eruption in 2010 increased mass concentration of PM10 (particulate matter, diameter <10 μm) were observed at ground level in Augsburg, Germany. In particular on 19 and 20 April 2010 the daily PM10 limit value of 50 μg m−3 was exceeded. Because ambient particles are in general a complex mixture originating from different sources, a source apportionment method (positive matrix factorization; PMF) was applied to particle size distribution data in the size range from 3 nm to 10 μm to identify and estimate the volcanic ash contribution to the overall PM10 load in the ambient air in Augsburg. A PMF factor with relevant particle mass concentration in the size range between 1 and 4 μm (maximum at 2 μm) was associated with long range transported dust. This factor increased from background concentration to high levels simultaneously with the arrival of the volcanic ash plume in the planetary boundary layer. Hence, we assume that this factor could be used as an indicator for the impact of the Eyjafjallajökull ash plume on ground level in Augsburg. From 17 to 22 April 2010 long range transported dust factor contributed on average 30.2 % (11.6 μg m−3) to PM10. On 19 April 2010 at 20:00 UTC+1 the maximum percentage of the long range transported dust factor accounted for around 65 % (35 μg m−3) to PM10 and three hours later the maximum absolute value with around 48 μg m−3 (61 %) was observed. Additional PMF analyses for a Saharan dust event occurred in May and June 2008 suggest, that the long range transported dust factor could also be used as an indicator for Saharan dust events.

scholarly journals Particle size distribution factor as an indicator for the impact of the Eyjafjallajökull ash plume at ground level in Augsburg, Germany

2011 ◽  
Vol 11 (17) ◽  
pp. 9367-9374 ◽  
Author(s):  
M. Pitz ◽  
J. Gu ◽  
J. Soentgen ◽  
A. Peters ◽  
J. Cyrys
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Long Range ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Size Range ◽  
Ground Level ◽  
Saharan Dust ◽  
Ash Plume ◽  
The Impact

Abstract. During the time period of the Eyjafjallajökull volcano eruption in 2010 increased mass concentration of PM10 (particulate matter, diameter <10 μm) were observed at ground level in Augsburg, Germany. In particular on 19 and 20 April 2010 the daily PM10 limit value of 50 μg m−3 was exceeded. Because ambient particles are in general a complex mixture originating from different sources, a source apportionment method (positive matrix factorization (PMF)) was applied to particle size distribution data in the size range from 3 nm to 10 μm to identify and estimate the volcanic ash contribution to the overall PM10 load in the ambient air in Augsburg. A PMF factor with relevant particle mass concentration in the size range between 1 and 4 μm (maximum at 2 μm) was associated with long range transported dust. This factor increased from background concentration to high levels simultaneously with the arrival of the volcanic ash plume in the planetary boundary layer. Hence, we assume that this factor could be used as an indicator for the impact of the Eyjafjallajökull ash plume on ground level in Augsburg. From 17 to 22 April 2010 long range transported dust factor contributed on average 30 % (12 μg m−3) to PM10. On 19 April 2010 at 20:00 UTC+1 the maximum percentage of the long range transported dust factor accounted for around 65 % (35 μg m−3) to PM10 and three hours later the maximum absolute value with around 48 μg m−3 (61 %) was observed. Additional PMF analyses for a Saharan dust event occurred in May and June 2008 suggest, that the long range transported dust factor could also be used as an indicator for Saharan dust events.

Airborne measurements of dust layer properties, particle size distribution and mixing state of Saharan dust during SAMUM 2006

Tellus B ◽  
2009 ◽  
Vol 61 (1) ◽  
Author(s):  
Bernadett Weinzierl ◽  
Andreas Petzold ◽  
Michael Esselborn ◽  
Martin Wirth ◽  
Katharina Rasp ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Saharan Dust ◽  
Mixing State ◽  
Dust Layer ◽  
Airborne Measurements

scholarly journals Simulation of Volcanic Ash Ingestion Into a Large Aero Engine: Particle–Fan Interactions

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Andreas Vogel ◽  
Adam J. Durant ◽  
Massimo Cassiani ◽  
Rory J. Clarkson ◽  
Michal Slaby ◽  
...  
Keyword(s):  
Particle Size ◽  
Stream Flow ◽  
Mass Concentration ◽  
Volcanic Ash ◽  
Particle Mass ◽  
Core Flow ◽  
Turbine Engine ◽  
The Core ◽  
Core Section ◽  
Particle Mass Concentration

Volcanic ash (VA) clouds in flight corridors present a significant threat to aircraft operations as VA particles can cause damage to gas turbine engine components that lead to a reduction of engine performance and compromise flight safety. In the last decade, research has mainly focused on processes such as erosion of compressor blades and static components caused by impinging ash particles as well as clogging and/or corrosion effects of soft or molten ash particles on hot section turbine airfoils and components. However, there is a lack of information on how the fan separates ingested VA particles from the core stream flow into the bypass flow and therefore influences the mass concentration inside the engine core section, which is most vulnerable and critical for safety. In this numerical simulation study, we investigated the VA particle–fan interactions and resulting reductions in particle mass concentrations entering the engine core section as a function of particle size, fan rotation rate, and for two different flight altitudes. For this, we used a high-bypass gas-turbine engine design, with representative intake, fan, spinner, and splitter geometries for numerical computational fluid dynamics (CFD) simulations including a Lagrangian particle-tracking algorithm. Our results reveal that particle–fan interactions redirect particles from the core stream flow into the bypass stream tube, which leads to a significant particle mass concentration reduction inside the engine core section. The results also show that the particle–fan interactions increase with increasing fan rotation rates and VA particle size. Depending on ingested VA size distributions, the particle mass inside the engine core flow can be up to 30% reduced compared to the incoming particle mass flow. The presented results enable future calculations of effective core flow exposure or dosages based on simulated or observed atmospheric VA particle size distribution, which is required to quantify engine failure mechanisms after exposure to VA. As an example, we applied our methodology to a recent aircraft encounter during the Mt. Kelud 2014 eruption. Based on ambient VA concentrations simulated with an atmospheric particle dispersion model (FLEXPART), we calculated the effective particle mass concentration inside the core stream flow along the actual flight track and compared it with the whole engine exposure.

scholarly journals Green Preparation, Spheroidal, and Superior Property of Nano-1,3,5,7-Tetranittro-1,3,5,7-Tetrazocane

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xinlei Jia ◽  
Jingyu Wang ◽  
Conghua Hou ◽  
Yingxin Tan
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Fractal Dimension ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fractal Theory ◽  
Crystal Form ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
The Impact

Herein, a green process for preparing nano-HMX, mechanical demulsification shearing (MDS) technology, was developed. Nano-HMX was successfully fabricated via MDS technology without using any chemical reagents, and the fabrication mechanism was proposed. Based on the “fractal theory,” the optimal shearing time for mechanical emulsification was deduced by calculating the fractal dimension of the particle size distribution. The as-prepared nano-HMX was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). And the impact sensitivities of HMX particles were contrastively investigated. The raw HMX had a lower fractal dimension of 1.9273. The ideal shearing time was 7 h. The resultant nano-HMX possessed a particle size distribution ranging from 203.3 nm to 509.1 nm as compared to raw HMX. Nano-HMX particles were dense spherical, maintaining β-HMX crystal form. In addition, they had much lower impact sensitivity. However, the apparent activation energy as well as thermal decomposition temperature of nano-HMX particles was decreased, attributing to the reduced probability for hotspot generation. Especially when the shearing time was 7 h, the activation energy was markedly decreased.

scholarly journals Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara

2020 ◽  
Author(s):  
Claire Ryder ◽  
Eleanor Highwood ◽  
Adrian Walser ◽  
Petra Walser ◽  
Anne Philipp ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Size Range ◽  
State Of The Art ◽  
Chem Phys ◽  
Saharan Dust ◽  
Dust Particles ◽  
Field Campaign ◽  
Dust Transport ◽  
Coarse Mode ◽  
Significant Underestimation

&lt;p&gt;Mineral dust is an important component of the climate system, interacting with radiation, clouds, and biogeochemical systems and impacting atmospheric circulation, air quality, aviation, and solar energy generation. These impacts are sensitive to dust particle size distribution (PSD), yet models struggle or even fail to represent coarse (diameter (&lt;span&gt;&lt;em&gt;d&lt;/em&gt;&lt;/span&gt;)&amp;#160;&lt;span&gt;&gt;2.5&lt;/span&gt;&amp;#8201;&lt;span&gt;&amp;#181;&lt;/span&gt;m) and giant (&lt;span&gt;&lt;em&gt;d&lt;/em&gt;&gt;20&lt;/span&gt;&amp;#8201;&lt;span&gt;&amp;#181;&lt;/span&gt;m) dust particles and the evolution of the PSD with transport. Here we examine three state-of-the-art airborne observational datasets, all of which measured the full size range of dust (&lt;span&gt;&lt;em&gt;d&lt;/em&gt;=0.1&lt;/span&gt;&amp;#160;to&amp;#160;&lt;span&gt;&gt;100&lt;/span&gt;&amp;#8201;&lt;span&gt;&amp;#181;&lt;/span&gt;m) at different stages during transport with consistent instrumentation. We quantify the presence and evolution of coarse and giant particles and their contribution to optical properties using airborne observations over the Sahara (from the Fennec field campaign) and in the Saharan Air Layer (SAL) over the tropical eastern Atlantic (from the AER-D field campaign).&lt;/p&gt;&lt;p&gt;Observations show significantly more abundant coarse and giant dust particles over the Sahara compared to the SAL: effective diameters of up to 20&amp;#8201;&lt;span&gt;&amp;#181;&lt;/span&gt;m were observed over the Sahara compared to 4&amp;#8201;&lt;span&gt;&amp;#181;&lt;/span&gt;m in the SAL. Excluding giant particles over the Sahara results in significant underestimation of mass concentration (40&amp;#8201;%), as well as underestimates of both shortwave and longwave extinction (18&amp;#8201;% and 26&amp;#8201;%, respectively, from scattering calculations), while the effects in the SAL are smaller but non-negligible. The larger impact on longwave extinction compared to shortwave implies a bias towards a radiative cooling effect in dust models, which typically exclude giant particles and underestimate coarse-mode concentrations.&lt;/p&gt;&lt;p&gt;A compilation of the new and published effective diameters against dust age since uplift time suggests that two regimes of dust transport exist. During the initial 1.5&amp;#8201;d, both coarse and giant particles are rapidly deposited. During the subsequent 1.5 to 10&amp;#8201;d, PSD barely changes with transport, and the coarse mode is retained to a much greater degree than expected from estimates of gravitational sedimentation alone. The reasons for this are unclear and warrant further investigation in order to improve dust transport schemes and the associated radiative effects of coarse and giant particles in models.&lt;/p&gt;&lt;p&gt;This work has been recently published in ACP (Ryder, C. L., Highwood, E. J., Walser, A., Seibert, P., Philipp, A., and Weinzierl, B.: Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara, Atmos. Chem. Phys., 19, 15353&amp;#8211;15376, https://doi.org/10.5194/acp-19-15353-2019, 2019).&lt;/p&gt;

scholarly journals Particle size distribution and particle mass measurements at urban, near-city and rural level in the Copenhagen area and Southern Sweden

2003 ◽  
Vol 3 (6) ◽  
pp. 5513-5546 ◽  
Author(s):  
M. Ketzel ◽  
P. Wåhlin ◽  
A. Kristensson ◽  
E. Swietlicki ◽  
R. Berkowicz ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Particle Number ◽  
Size Range ◽  
Urban Background ◽  
Total Particle ◽  
Urban Level ◽  
20 Nm ◽  
Traffic Source

Abstract. Particle size distribution (size-range 3–900 nm) and PM10 was measured simultaneously at an urban background station in Copenhagen, a near-city background and a rural location during a period in September-November 2002. The study investigates the contribution from urban versus regional sources of particle number and mass concentration. The total particle number (ToN) and NOx are well correlated at the urban and near-city level and show a distinct diurnal variation, indicating the common traffic source. The average ToN at the three stations differs by a factor of 3. The observed concentrations are 2500 # cm−3, 4500 # cm−3 and 7700 # cm−3 at rural, near-city and urban level, respectively. PM10 and total particle volume (ToV) are well correlated between the three different stations and show similar concentration levels, in average within 30% relative difference, indicating a common source from long-range transport that dominates the concentrations at all locations. Measures to reduce the local urban emissions of NOx and ToN are likely to affect both the street level and urban background concentrations, while for PM10 and ToV only measurable effects at the street level are probable. Taking into account the supposed stronger health effects of ultrafine particles reduction measures should address particle number emissions. The traffic source contributes strongest in the 10–200 nm particle size range. The maximum of the size distribution shifts from about 20–30 nm at kerbside to 50–60 nm at rural level. We also observe particle formation events in the 3–20 nm size range at rural location in the afternoon hours, mainly under conditions with low concentrations of pre-existing aerosol particles. The maximum in the size distribution of the "traffic contribution" seems to be shifted to about 28 nm in the urban location compared to 22 nm at kerbside. Assuming NOx as an inert tracer on urban scale let us estimate that ToN at urban level is reduced by 15–30% compared to kerbside. Particle removal processes, e.g. deposition and coagulation, which are most efficient for smallest particle sizes (<20 nm) and condensational growth are likely mechanisms for the loss of particle number and the shift in particle size.

scholarly journals Airborne observations of the Eyjafjalla volcano ash cloud over Europe during air space closure in April and May 2010

2011 ◽  
Vol 11 (5) ◽  
pp. 2245-2279 ◽  
Author(s):  
U. Schumann ◽  
B. Weinzierl ◽  
O. Reitebuch ◽  
H. Schlager ◽  
A. Minikin ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Volcanic Ash ◽  
Particle Density ◽  
Airborne Lidar ◽  
Particle Sedimentation ◽  
Space Closure ◽  
Ash Plume ◽  
Ground Based Lidar ◽  
Ash Cloud ◽  
Mass Concentrations

Abstract. Airborne lidar and in-situ measurements of aerosols and trace gases were performed in volcanic ash plumes over Europe between Southern Germany and Iceland with the Falcon aircraft during the eruption period of the Eyjafjalla volcano between 19 April and 18 May 2010. Flight planning and measurement analyses were supported by a refined Meteosat ash product and trajectory model analysis. The volcanic ash plume was observed with lidar directly over the volcano and up to a distance of 2700 km downwind, and up to 120 h plume ages. Aged ash layers were between a few 100 m to 3 km deep, occurred between 1 and 7 km altitude, and were typically 100 to 300 km wide. Particles collected by impactors had diameters up to 20 μm diameter, with size and age dependent composition. Ash mass concentrations were derived from optical particle spectrometers for a particle density of 2.6 g cm−3 and various values of the refractive index (RI, real part: 1.59; 3 values for the imaginary part: 0, 0.004 and 0.008). The mass concentrations, effective diameters and related optical properties were compared with ground-based lidar observations. Theoretical considerations of particle sedimentation constrain the particle diameters to those obtained for the lower RI values. The ash mass concentration results have an uncertainty of a factor of two. The maximum ash mass concentration encountered during the 17 flights with 34 ash plume penetrations was below 1 mg m−3. The Falcon flew in ash clouds up to about 0.8 mg m−3 for a few minutes and in an ash cloud with approximately 0.2 mg m−3 mean-concentration for about one hour without engine damage. The ash plumes were rather dry and correlated with considerable CO and SO2 increases and O3 decreases. To first order, ash concentration and SO2 mixing ratio in the plumes decreased by a factor of two within less than a day. In fresh plumes, the SO2 and CO concentration increases were correlated with the ash mass concentration. The ash plumes were often visible slantwise as faint dark layers, even for concentrations below 0.1 mg m−3. The large abundance of volatile Aitken mode particles suggests previous nucleation of sulfuric acid droplets. The effective diameters range between 0.2 and 3 μm with considerable surface and volume contributions from the Aitken and coarse mode aerosol, respectively. The distal ash mass flux on 2 May was of the order of 500 (240–1600) kg s−1. The volcano induced about 10 (2.5–50) Tg of distal ash mass and about 3 (0.6–23) Tg of SO2 during the whole eruption period. The results of the Falcon flights were used to support the responsible agencies in their decisions concerning air traffic in the presence of volcanic ash.

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