scholarly journals Development and evaluation of desert dust emission model

2021 ◽  
Author(s):  
Σεραφείμ Κόντος
Keyword(s):  
Dust Emission ◽  
Emission Model ◽  
Desert Dust

Αντικείμενο της διατριβής αυτής είναι η μελέτη των παραμετροποιήσεων μοντελοποίησης της σκόνης από ερημικές και ημιερημικές περιοχές, μέσω της ανάπτυξης και αξιολόγησης μοντέλου φυσικών εκπομπών. Στο πλαίσιο του διδακτορικού αναπτύχθηκαν και επικαιροποιήθηκαν οι αλγόριθμοι του μοντέλου φυσικών εκπομπών ΝΕΜΟ, το οποίο έχει αναπτυχθεί στο Εργαστήριο Φυσικής της Ατμόσφαιρας του Α.Π.Θ., ώστε να αποδίδει και την παραγωγή ερημικής σκόνης. Οι παραμετροποίήσεις που αναπτύχθηκαν στο ΝΕΜΟ εφαρμόστηκαν στην περιοχή της Μέσης Ανατολής, προκειμένου να αναλυθούν οι διαφοροποιήσεις σε επίπεδο εκπομπών, καθώς και να αξιολογηθούν με τελικό σκοπό την ανεύρεση του βέλτιστου συνδυασμού(ων) παραμετροποιήσεων.

scholarly journals Dust Distribution in IRAS Seyfert Galaxies

1994 ◽  
Vol 159 ◽  
pp. 355-355
Author(s):  
M. G. Pastoriza ◽  
Charles Bonatto ◽  
Eduardo Bica ◽  
T. Storchi-Bergmann
Keyword(s):  
Emission Line ◽  
Power Law ◽  
Dust Emission ◽  
Seyfert Galaxies ◽  
Emission Model ◽  
Line Region ◽  
Population Type ◽  
The Galaxy ◽  
Dilution Effects ◽  
Dust Distribution

Observational evidences of dust in the nuclear region of AGNs are substantial (Rudy 1984, ApJ, 284, 33; Jones et al. 1984, PASP, 96, 692). The ionization cones observed in several Seyfert galaxies has been interpreted as shadowing effects by a dust obscuring torus which hides the broad emission line region (BLR) and the central source (Wilson 1992; Storchi-Bergmann, Mulchaey and Wilson 1992, ApJ 395, L73). A large sample of optical and far-IR data for IRAS Seyfert galaxies has been analysed together with dust emission models (Bonatto and Pastoriza 1993), where it has been concluded that the same dust emission model can be applied to both Seyfert types. In order to further study the effects of dust in the spectra of active galactic nuclei, we have obtained spectrophotometry of 21 IRAS Seyfert galaxies in the range 3500–7200 Å and analyse them in conjuction with their IRAS fluxes. The stellar population type is derived from comparisons with normal galaxy templates using dilution effects in the K CaII line as discriminator. For 55% of the sample the population is of late type. For the rest, blue continua due to recent star formation and/or power-law may amount up to 30% at 4000Å. We conclude that the bulge stellar populations of IRAS Seyfert galaxies are similar to those of normal spirals, except that they are more reddened by E(B-V)i ∼ 0.20. Population-subtracted emission line ratios indicate on average stronger reddening for the narrow-line region (E(B-V)l ∼ 0.8. From photoionization models a power-law index for the ionizing continuum α=1.5, and a metallicity larger than solar are obtained. The most luminous IRAS galaxy of the sample (IRAS555) is discuss in detail: in order to be compatible with the observed IRAS fluxes and the optical stellar continuum, the ionizing continuum must be reddened by AV > 10 magnitudes. Consequently a dust structure in this galaxy appears to be increasingly affecting stars and gas towards the galaxy center.

scholarly journals Long-term assessment of airborne radiocesium after the Fukushima nuclear accident: Re-suspension from bare soil and forest ecosystems

2016 ◽  
Author(s):  
M. Kajino ◽  
M. Ishizuka ◽  
Y. Igarashi ◽  
K. Kita ◽  
C. Yoshikawa ◽  
...  
Keyword(s):  
Land Surface ◽  
Forest Ecosystems ◽  
Field Experiments ◽  
Dust Emission ◽  
Nuclear Accident ◽  
Fukushima Nuclear Accident ◽  
Emission Model ◽  
Air Concentration ◽  
Contaminated Area

Abstract. The long-term effect of 137Cs re-suspension from contaminated soil and forests due to the Fukushima nuclear accident has been quantitatively assessed by numerical simulation, a field experiment on dust emission flux in the contaminated area (Namie, Fukushima), and air concentration measurements inside (Namie) and outside (Tsukuba, Ibaraki) the contaminated area. The assessment period is for the year 2013 just after the start of the field experiments, December 14, 2012. The 137Cs concentrations at Namie and Tsukuba were approximately 10−1–1 and 10−2–10−1 mBq/m3, respectively. The observed monthly median concentration at Namie was one to two orders of magnitude larger than that at Tsukuba. This observed difference between the two sites was consistent with the simulated difference, indicating successful modeling of 137Cs re-suspension and atmospheric transport. The estimated re-suspension rate was approximately 10−6/d, which was significantly lower than the decreasing rate of the ambient gamma dose rate in Fukushima prefecture (10−4–10−3/d) as a result of radioactive decay, land surface processes (migration in the soil and biota), and decontamination. Consequently, re-suspension contributed negligibly to reducing ground radioactivity. The dust emission model could account for the air concentration of 137Cs in winter, whereas the summer air concentration was underestimated by one to two orders of magnitude. Re-suspension from forests at a constant rate of 10−7/h, multiplied by the green area fraction, quantitatively accounted for the air concentration of 137Cs at Namie and its seasonal variation. The simulated contribution of dust re-suspension to the air concentration was 0.6–0.8 in the cold season and 0.1–0.4 in the warm season at both sites; the remainder of the contribution was re-suspension from forest. The re-suspension mechanisms, especially through the forest ecosystems, remain unknown, and thus the current study is the first but crude estimation of the long-term assessment of radiocesium re-suspension. Further study will be needed to understand the re-suspension mechanisms and to accurately assess the re-suspension mechanisms through field experiments and numerical simulations.

scholarly journals A dust emission model of Lyman-break galaxies

2004 ◽  
Vol 426 (2) ◽  
pp. 425-435 ◽  
Author(s):  
T. T. Takeuchi ◽  
T. T. Ishii
Keyword(s):  
Dust Emission ◽  
Emission Model ◽  
Lyman Break Galaxies

scholarly journals A large source of dust missing in Particulate Matter emission inventories? Wind erosion of post-fire landscapes

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
N. S. Wagenbrenner ◽  
S. H. Chung ◽  
B. K. Lamb
Keyword(s):  
Particulate Matter ◽  
Wind Erosion ◽  
Dust Emission ◽  
Emission Model ◽  
Modeling Framework ◽  
Dust Emissions ◽  
Fire Scar ◽  
Large Source ◽  
Precipitation Regimes ◽  
Flux Measurements

Wind erosion of soils burned by wildfire contributes substantial particulate matter (PM) in the form of dust to the atmosphere, but the magnitude of this dust source is largely unknown. It is important to accurately quantify dust emissions because they can impact human health, degrade visibility, exacerbate dust-on-snow issues (including snowmelt timing, snow chemistry, and avalanche danger), and affect ecological and biogeochemical cycles, precipitation regimes, and the Earth’s radiation budget. We used a novel modeling approach in which local-scale winds were used to drive a high-resolution dust emission model parameterized for burned soils to provide a first estimate of post-fire PM emissions. The dust emission model was parameterized with dust flux measurements from a 2010 fire scar. Here we present a case study to demonstrate the ability of the modeling framework to capture the onset and dynamics of a post-fire dust event and then use the modeling framework to estimate PM emissions from burn scars left by wildfires in U.S. western sagebrush landscapes during 2012. Modeled emissions from 1.2 million ha of burned soil totaled 32.1 Tg (11.7–352 Tg) of dust as PM10 and 12.8 Tg (4.68–141 Tg) as PM2.5. Despite the relatively large uncertainties in these estimates and a number of underlying assumptions, these first estimates of annual post-fire dust emissions suggest that post-fire PM emissions could substantially increase current annual PM estimates in the U.S. National Emissions Inventory during high fire activity years. Given the potential for post-fire scars to be a large source of PM, further on-site PM flux measurements are needed to improve emission parameterizations and constrain these first estimates.

A Zodiacal Dust Emission Model

1988 ◽  
pp. 337-344 ◽  
Author(s):  
P. Temi ◽  
P. de Bernardis ◽  
S. Masi ◽  
G. Moreno ◽  
A. Salama
Keyword(s):  
Dust Emission ◽  
Emission Model ◽  
Zodiacal Dust

Mineral dust aerosol from Saharan desert by means of atmospheric, emission, dispersion modelling

2011 ◽  
Vol 8 (4) ◽  
pp. 7313-7338 ◽  
Author(s):  
F. Guarnieri ◽  
F. Calastrini ◽  
C. Busillo ◽  
M. Pasqui ◽  
S. Becagli ◽  
...  
Keyword(s):  
Prediction Models ◽  
Mineral Dust ◽  
Dust Emission ◽  
Atmospheric Model ◽  
Saharan Dust ◽  
Emission Model ◽  
Good Correspondence ◽  
Comparison Of The Results ◽  
Modelling System

Abstract. The application of Numerical Prediction Models to mineral dust cycle is considered of prime importance for the investigation of aerosol and non-CO2 greenhouse gases contributions in climate variability and change. In this framework, a modelling system was developed in order to provide a regional characterization of Saharan dust intrusions over Mediterranean basin. The model chain is based on three different modules: the atmospheric model, the dust emission model and transport/deposition model. Numerical simulations for a selected case study, June 2006, were performed in order to evaluate the modelling system effectiveness. The comparison of the results obtained in such a case study shows a good agreement with those coming from GOCART model. Moreover a good correspondence was found in the comparison with in-situ measurements regarding some specific crustal markers in the PM10 fraction.

Modelling an exceptional desert dust transport toward Portugal on February 2017

2020 ◽  
Author(s):  
Maria João Costa ◽  
Flavio Couto ◽  
Eduardo Cardoso ◽  
Rui Salgado ◽  
Juan Luis Guerrero-Rascado
Keyword(s):  
Iberian Peninsula ◽  
Atmospheric Circulation ◽  
Dust Emission ◽  
Horizontal Resolution ◽  
Sahara Desert ◽  
Dust Transport ◽  
Western Sahara ◽  
Orographic Effects ◽  
Desert Dust ◽  
The North

<p>The terrain surrounding the Sahara desert is formed by some mountains ranges, as the Atlas mountain system in the northern edge of the desert and the Hoggar Mountains in Southern Algeria. Such orography, jointly with atmospheric circulation, plays an important role in the mobilization and transport of desert dust over medium and large distances. This study explores the interaction between complex terrain and atmospheric circulation in order to better understand an exceptional desert dust outbreak affecting Portugal in February 2017. The Meso-NH model is able to represent the atmospheric motions in different scales, and has been implemented with a rather complete parametrization package of physical processes in the atmosphere. The capability of the model to simulate dust emission is also explored. The on-line dust emission parametrization type is taken from the distribution of emitted dust of SURFEX with no need to use chemistry to activate dusts. A set of two simulations was performed for the period between 16 February at 0000 UTC to 24 February 1200 UTC, with the Meso-NH model configured in a single domain at 10 km horizontal resolution and 300x360 grid points. The experiments were defined as a) control experiment (CTRL), and b) dust experiment (DUST). From the large domain simulations, it was possible to assess the source of dust and its mobilization over Western Sahara desert, namely over the Northern part of Mauritania and Mali and Eastern part of Algeria. The formation of a cyclonic circulation at the surface favoured the dust uplifting. Such a surface low merged with a cut-off low that moved southward over the Iberian Peninsula and remained centred in the north of Morocco. Such pattern intensified the northward flow found at 700 hPa toward the Atlas Mountains range, inducing the dust transport above 3 km altitude. As expected, the simulations showed the ability to assess important details about the atmospheric circulation not resolved by low density of observations over the domain considered. Furthermore, the simulations were able to show the way that the atmospheric ingredients were brought together to produce the exceptional transport of desert dust toward Portugal. The orographic effects playing an important role in dust mobilization (convergence and cyclogenesis at the surface) and atmospheric circulation to the maintenance of the dust transport have been highlighted. Such event were responsible for the transport of high amount of dust toward the Iberian Peninsula.</p>

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