دانلود رایگان مقاله لاتین مطالعه گرد و غبار از سایت الزویر
عنوان فارسی مقاله:
مطالعه عددی در گرد و غبار با مفاهیم برآورد بودجه گرد و غبار جهانی
عنوان انگلیسی مقاله:
A numerical study on dust devils with implications to global dust budget estimates
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Dust devils (DDs) are small dust carrying vortices. They occur frequently on Earth and Mars, but their contributions to the terrestrial and martian dust budget are so far not well quantified. DDs are subgrid systems in global models and it is not clear how DD dust emission can be parameterized. Renno et al. (1998) developed a thermodynamic theory for DD occurrence and intensity, and based on this theory, Koch and Renno (2005) estimated the contribution of DDs to the terrestrial dust budget to be 26 18%. In their estimate, DD dust fluxes are determined from the maximum dust concentration and vertical wind speed measured in a small number of strong DDs. The resulting dust fluxes are not necessarily the surface dust fluxes and may lead to an overestimation of the DD dust contribution. Jemmett-Smith et al. (2015) used meteorological criteria to estimate the potential of DD occurrence, and found a much lower global DD contribution of 3.4% (estimates range from 0.9 to 31% depending on the criteria used). To obtain this estimate, Jemmett-Smith et al. (2015) used the same fractional updraft areas and dust fluxes as Koch and Renno (2005). Dust emission mechanisms in DDs are subject to ongoing research. Saltation bombardment, the process in which dust emission is generated by impacts of hopping sand-sized grains, does not alone explain dust emission in DDs, as the necessary condition to initiate saltation (i.e. the friction velocity, u, must be larger than the threshold friction velocity for saltation, ut) is often not reached. Other mechanisms specific to DD dust emission have been suggested, such as dust uplift due to a vertical pressure drop at the surface (suction), but the significance of this process has not yet been quantitatively determined (Balme and Hagermann, 2006). Also, the vertical pressure drop may be related to the tangential vortex speed, thus the consideration of vortex velocity may be suf- ficient in the study of DDs (Wang, 2016). As pressure drop is easier to measure than tangential vortex speed, it is often used as a direct indicator for DD intensity and DD dust load (e.g. Neakrase and Greeley, 2010; Metzger et al., 2011; Lorenz and Jackson, 2015). Klose and Shao (2012) and Klose et al. (2014) have developed a parameterization for the direct aerodynamic dust entrainment by turbulence. The scheme focuses on convective conditions, the situation when DDs develop, and takes account of the stochastic nature of both atmospheric particle lifting forces and surface interparticle cohesive forces.
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کلمات کلیدی:
Quantifying global dust devil occurrence from meteorological analyses https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4670712/ by BC Jemmett-Smith - 2015 - Cited by 21 - Related articles Feb 26, 2015 - Global potential dust devil occurrence quantified from meteorological analyses ... [Knippertz and Stuut, 2014] with implications for the global energy, carbon, ... dust forms the largest component of the global aerosol budget, ... [PDF]Dust opacities inside the dust devil column in the ... - Atmos. Meas. Tech www.atmos-meas-tech.net/10/273/2017/amt-10-273-2017.pdf by Z Luan - 2017 Jan 24, 2017 - while recent studies show that global dust uplift by DDs is about 3.4% ..... implications to global dust budget estimates, Aeolian Research,. [PDF]Dust Devil Sediment Transport: From Lab to Field to Global Impact www.lmd.jussieu.fr/~aspiga/pub/REF/2016SSRv..203..377K.pdf Jul 4, 2016 - Dust devils are a common occurrence on Mars and in semi-arid and arid ...... on dust devils with implications to global dust budget estimates. Geomorphology of Desert Environments https://books.google.com/books?isbn=1402057199 Anthony J. Parsons, A. D. Abrahams - 2009 - Science Dust deposition in southern Nevada and California, 1984–1989: relations to climate, source area ... sequences and coversands: methodological aspects and palaeoclimatic implications. ... A numerical study of the contributions of dust source regions to the global dust budget. ... A close encounter with a terrestrial dust devil. Development and evaluation of a physics-based windblown dust ... www.wileyopenaccess.com/view/.../journalArticleReferences.html Mar 3, 2017 - Gillette, D. A. (1988), Threshold friction velocities for dust production for .... on dust devils with implications to global dust budget estimates, ...
