The Northern Path of Asian Dust Transport from the Gobi Desert to North America

The aerosol index (AI) of the Total Ozone Mapping Spectrometer (TOMS) satellite data (1979 2001) was analyzed to reveal the climatological long-distance path of dust transport from Asia to North America. The AI in the west coast of the United States is highly correlated with that in the Gobi desert. Additionally, from the TOMS satellite images, it can be seen that very strong plumes advect from Asia to the west coast of North America in typical dust storm cases. When applying the sourcereceptor relationship to detect the northern dust transport path between the Gobi source region and the west coast of the United States receptor region, it is evident that the dust plume can be transported northward beyond 60°N from its source region and that it takes 5 to 6 days to reach the west coast of the United States. The cross correlation technique shown in this work is a useful tool that can be applied in other regions to give useful insights into relationships between major dust sources and downwind receptor locations by using remotely sensed dust observations.

Monitoring Mongolia Gobi dust transport using OMI data

The characteristics of long-distance dust transport from Asia to the United States over the Pacific Ocean are statistically analyzed using OMI AI （Ozone Monitoring Instrument Aerosol Index） data during 2005-007. The results show that there is a high correla- tion of At （the correlation coefficients are as high as 0.83 in March, 0.62 in April and 054 in May） between the Mongolia Gobi Desert and the west coast region of the United States （40°-50°N, 120°- 130°W）, indicating a strong source-receptor area relationship. Through calculating the lag correlation coefficient of the dust propagation time, we determined that the dust propagation lime fi＇om the Mongolia Gobi Desert to the west coast of the United States is about 6-7 days at the 99% confidence level.

Impact of Long-range Desert Dust Transport on Hydrometeor Formation over Coastal East Asia

Model simulations and hydrological reanalysis data for 2007 are applied to investigate the impact of long-range desert dust transport on hydrometeor formation over coastal East Asia. Results are analyzed from Hong Kong and Shanghai, which are two representative coastal cities of East Asia. Long-range desert dust transport impacts mainly spring and summer clouds and precipitation over coastal East Asia. In spring, clouds and precipitation come mainly from large-scale condensation and are impacted mainly by dust from the Gobi, Sahara, and Thar deserts. These desert dusts can participate in the precipitation within and below the clouds. At lower latitudes, the dust particles act mainly as water nuclei. At higher latitudes, they act as both water nuclei and ice nuclei. The effect of Gobi, Sahara, and Thar dust on large-scale clouds and precipitation becomes stronger at higher latitudes. In summer, clouds and precipitation over coastal East Asia come mainly from convection and are impacted mainly by dust from the Taklamakan, Arabian, and Karakum-Kavir deserts. Most Taklamakan dust particles can participate in precipitation within convective clouds as ice nuclei, while Arabian and Karakum-Kavir dust particles participate only as water nuclei in precipitation below the clouds. The effect of Taklamakan dust on convective clouds and precipitation becomes stronger at lower latitudes. Of all the desert dusts, that from the Gobi and Taklamakan deserts has the relatively largest impact. Gobi dust impacts climate change in coastal East Asia by affecting spring water clouds at higher latitudes.

The Cross-Correlation Function as a Tool for Detecting Source-Receptor Relationships:Application to Asian Dust Transport to North America

The cross-correlation function was used in conjunction with the daily values of the aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) to establish and qualify a source-receptor relationship between dust over the Gobi desert and the West Coast of the United States.An objective method that can be used to determine the trajectory of dust transport and the transportation time at different locations along the trajectory across the Pacific are presented in this report.The spring season was analyzed (March to May),and the results showed that dust reaches the western United States in approximately five to six days.Although dust transport from the Gobi desert was demonstrated in the present study,the proposed cross-correlation technique can be applied to other regions and can be used to obtain useful insights on relationships between major dust sources and downwind receptor locations utilizing remotely sensed dust estimates.

A Unique Case-Study of Near-Circular Saharan Dust Transport over the Atlantic Ocean

An occurrence of transportation of Saharan dust from equatorial West African and back to Europe and Africa around theAtlantic Oceanwas synoptically analyzed. The entire circle around the Atlantic took twelve days. The direction and speed of the dust cloud was governed by the position, the strength and the movement of the Center of Activity (COA) of the Azores High. This type of trajectory is quite rare. In the year 2009 (the year of the analyzed trajectory) it occurred only 8 times. We assume, that the interesting point in this type of trajectory is the possibility that in its long way, it collects from and deposits in, different types of aerosols at the American European and African continents and the Ocean between them.

Dust transport information and paleoclimatic changes revealed by the loess in Ranwu,south-eastern Xizang

The loess accumulation process has great potential to record patterns of atmospheric circulation change,paleoclimate,and paleoenvironmental evolution.South-eastern Xizang is a climatically sensitive region and here,we analyze a loess profile at Ranwu in order to explore the processes and interactions of dust transport and paleoclimate evolution in the region.Based on parametric grain size end-member analysis,optically stimulated luminescence(OSL)dating,and environmental proxies we show that the Ranwu loess profile comprises five end members(EMs).EM1 represents the fine silt fraction transported by high-altitude westerly winds over long distances;EM2 represents the medium silt fraction accumulated by glacier winds;EM3 is the coarse silt fraction transported by local dust storms under the action of strong glacier winds;EM4 represents the very fine sand fraction transported by strong local dust storms,different wind strengths controls the relative proportion of EM3 and EM4 over time.EM5 is the coarse sand fraction formed from the product of strong weathering of gravels.OSL dating shows loess sedimentation at Ranwu started around 11.16 ka.The prevailing climate was generally warm and wet between 11.6 and 4.2 ka,with four cooling events at 10.50,9.18,7.85,and 6.37 ka.Extensive paleosol development between 8.2 and 4.2 ka,a change to dry and cold climate conditions was favorable for loess formation after 4.2 ka.The palaeoenvironmental changes and abrupt climate events recorded in the Ranwu loess sequence are consistent with Holocene global environmental changes.

Long range trans-Pacific transport and deposition of Asian dust aerosols

The deposition of Asian dust aerosols during their trans-Pacific transport might cause significant marine phytoplankton biomass increases. However, the knowledge of the trans-Pacific dust transport, deposition, and spatial distribution is still poor due to a lack of continuous and simultaneous observations in the Asian subcontinent, the north Pacific Ocean, and North America. The severe Asian dust storm during 6 to 9 April 2001 provided an opportunity to gain a better understanding of trans-Pacific dust transport and deposition, using a comprehensive set of observations from satellites, ground-based light detection and ranging, aircraft, and surface observation networks. The observations and model simulations outline the general pattern of dust transport, deposition, vertical profile, and spatial distribution. The following points were observed： （1） the surface dust concentrations decreased exponentially with the increasing dust transport distance from 80°E to 120°W along the transport pathway; （2） the altitude of the dust concentration peak increased with increasing transport distance in the north Pacific region; and （3） the spatial distribution of dust deposition mainly depended on the trans-Pacific transport route.

An Observational and Numerical Study on the Topographic Influence on Dust Transport in East Asia

Based on observations and numerical simulations, the topographic impacts on dust transport in East Asia were studied. Two regions frequently attacked by dust storms have been confirmed： one is the western part of Inner Mongolia and the southern Mongolia （namely the Mongolia Plateau）, and the other is the Tarim Basin. The most frequent dust storm occurrence area within the first region appears in its hinterland while that of the second one lies in its southern boundary. Moreover, the region from the northeastern edge of the Tibetan Plateau （TP） to the Loess Plateau is attacked by dust storms second frequently. The dust storms frequently occurring over the Mongolia Plateau axe related not only to the abundant sand and dust sources, but also to the special topographic conditions of East Asia. The most significant factor that influences the dust storms forming in the hinterland of the Mongolia Plateau is the canyon low level jet （CLLJ）, which dominates around the southern areas of the Altay-Sayan Mountains with an east-west direction in the beginning of its formation, and is accompanied by significantly enhanced surface wind afterwards. Due to the obstructive effects of the CLLJ, a lot of dust particles carried by the southward down-slope cold air mass would pile up over the southern slope of the Sayan Mountains. Meanwhile, uneven surface conditions are favorable for the dust particles to go up into the upper atmosphere. With the dust particles piling up continuously, a dust layer is formed in the troposphere and can be recognized as a ＇!dust accumulating container＂, which provides abundant dust particles to be transported later to the downstream areas. Additionally, the topographic features of East Asia also exert a great influence on dust transport. Generally, the easterly CLLJ enhances the easterly dust transport. The down-slope air current over the southern Sayan Mountains and the air flow surrounding the TP near its northeastern edge enhance the southward dust transport. Lastly, weather system influences are also examined. The weathers associated with cold fronts frequently appear over the areas of Mongolia and North China in springtime. The cold front system, in general, carries the sand and dust southwards. Among all topographic influencing elements, the rounding effect of the TP is the strongest. Under the combined influences of the cold front and the rounding effect of topography, most sand and dust particles are transported and then deposited over the Loess Plateau.

Simulation of DC glow discharge plasma with free-moving dust particles in the radial direction

A self-consistent fluid model is developed to investigate the radial distributions of dusty plasma parameters in a DC glow discharge,in which the extended fluid approach of plasma particles and the transport equations of dust particles are coupled.The electrical interaction between charged dust particles is considered in the model.The time evolution of radial distributions of dust density,plasma density,the radial component of electric field and the forces acting on dust particles when dust density tends to be stable,are obtained and analyzed under different discharge currents and dust particle radii.It is shown that the dust density structure is determined mainly by the radial electrostatic force,thermophoretic force and ion drag force in the discharge tube,and both discharge current and dust particle radius have an obvious effect on the transport processes of dust particles.The dust particles gather in the central region of the discharge tube for low discharge current and small dust radius,then dust voids are formed and become wider when the discharge current and dust radius increase.The plasma parameters in the dust gathering region are obviously affected by the dust particles due to the charging processes of electrons and ions to the dust surface.

The possible pivotal role of the eastward dust transport from Central Asia in the global temperature decrease

glacial-interglacialgyrations 的出现能与 Milankovitch 理论被解释，这通常被考虑。然而，在理论的一些问题的答案还当前没被导出。在从 CentralAsia 研究东方灰尘运输以后，我们发现了在东方灰尘运输和全球温度减少之间有积极反馈机制。这在北半球的 thehigh 纬度区域放大太阳的放射变化的效果，并且导致全球冰川的时代的出现。积极反馈机制在北半球的 thehigh 纬度区域以太阳的放射的减小开始。随后，全球温度减少，全球冰川的历元发生，在哪个枢轴的因素是从 CentralAsia 的东方灰尘运输。与积极反馈机制的理论，在 Milankovitch 理论的一些问题能被解决很好。

斜巷转载点粉尘污染规律及多断面雾幕控尘技术研究

针对斜巷转载点粉尘污染严重的问题,运用COMSOL软件对棋盘井煤矿3号转载点进行了几何建模,并基于计算流体力学(CFD)粒子追踪模型、有限元法和k-ε湍流模型,计算了3号转载点风流流线分布、速度多切面分布以及粉尘粒子运动轨迹,研究了生产工作时3号转载点处风流变化及粉尘运移规律,并针对性地提出了一种多断面雾幕控尘技术。该技术基于螺旋雾幕控尘、超音速隔尘原理,可形成距离长、覆盖范围广的雾幕以最大限度包裹粉尘颗粒,实现粉尘高效净化。最后通过控尘试验及在棋盘井煤矿3号转载点现场应用,验证了该技术的高效降尘特性以及可靠性。研究结果表明:风流分布主要受皮带速度、牵引力和诱导气流的综合作用影响,沿水平和垂直方向分层分布,形成密集且平均速度为0.5 m/s的涡流;粉尘易受涡流影响向四周扩散,主要分布在下风侧,粒径为5~15μm更容易受风流牵引扩散,聚集于工人呼吸带高度,污染严重。将该技术进行控尘试验和现场应用后,全尘和呼尘降尘效率分别高达93.65%、85.59%以上。

高海拔隧道喷浆出碴过程风速场及粉尘分布规律数值模拟研究

为明确气压等环境参数对粉尘运移的影响,掌握高海拔隧道空间重点产尘工序粉尘质量浓度分布,使用Fluent软件模拟隧道喷浆和出碴阶段风速场和粉尘质量浓度场,分析海拔对隧道空间内风流和粉尘质量浓度波动性的影响。通过曲线拟合风速场和粉尘质量浓度场的沿程分布,建立隧道粉尘质量浓度预测模型。引入风速不均匀度和粉尘质量浓度不均匀度参数,构建海拔与风速、粉尘质量浓度不均匀度的线性回归方程。研究结果表明:1)高海拔地区隧道通风过程中,粉尘运移速度接近风速所用时间相比平原地区较长;低海拔地区风流接近直线沿全断面流出隧道,随着海拔升高,风流覆盖范围逐渐缩小,风流在水平方向逐渐沿S型流出隧道。2)喷浆过程中,距掌子面40 m以内风速较高,40 m以外风速迅速下降,在距掌子面60~180 m均匀波动;隧道整体粉尘质量浓度随海拔上升而发生波动性变化,在距掌子面20~180 m均匀下降,呈近似线性降低。3)出碴过程中,海拔上升,断面平均风速和呼吸面平均粉尘质量浓度值无明显变化,风速不均匀度和粉尘质量浓度不均匀度逐渐呈线性升高;海拔每上升1 000 m,风速不均匀度上升0.156 m^(2)/s^(2),粉尘质量浓度不均匀度上升4.42×10^(-6)kg/m^(3)。

气流输运工况玉米淀粉爆炸火焰传播与压力特性实验研究

利用自主搭建的2 m长气流输运管道实验装置开展了不同气流速度下玉米淀粉爆炸实验,通过高速摄影和压力传感器获得火焰信息和压力参数。基于实验结果分析了气流输运工况气流速度对玉米淀粉爆炸火焰传播行为和爆炸特性的影响规律。结果表明:随着气流速度的增加,粉尘爆炸火焰亮度、火焰传播速度及最大爆炸压力呈先增大后减小的趋势,存在火焰呈螺旋状向管道末端传播的现象。气流速度从5 m/s升至10 m/s,火焰最大传播速度从74.07 m/s增加到89.51 m/s,最大爆炸压力由17.08 kPa增至23.42 kPa。气流速度提高到15 m/s时,火焰最大传播速度和爆炸压力均有所下降,质量浓度为300 g/m3时受影响最大,爆炸压力降低41%,500 g/m3时受影响最小,爆炸压力下降7.4%。

基于激光雷达观测的呼伦贝尔一次沙尘过程分析

基于测风激光雷达和地面常规观测资料,借助机器学习算法以及HYSPLIT(Hybrid Single-Particle LagrangianIntegrated Trajectory)模型分析了发生在呼伦贝尔的一次典型的沙尘天气过程。研究表明,本次沙尘起始时南风突增,风向转西南偏南风后风速降低,传输减弱,当风向转西风时,沙尘传输增强,在西风降低后沙尘传输结束。沙尘传输期间,湍流运动偏弱,混合层高度抬升受限。借助机器学习分粒径计算发现,沙尘前期传输以粗颗粒为主,后期粗、细颗粒物均有明显增长。不同传输时期粒径的不同,暗示沙尘的源可能发生变化,后向轨迹揭示沙尘传输前期来自蒙古国西北部,经过我国锡林郭勒后北上到达呼伦贝尔;而后期沙尘是从俄罗斯南部直接进入呼伦贝尔。最后研究发现,沙尘前至起始时刻,总传输通量对沙尘的响应早于地面颗粒物浓度变化,且沙尘期间总传输通量值显著高于沙尘前和沙尘后。因此,总传输通量变化以及阈值设定可为沙尘预警的新参考指标。

2021年宁夏两次持续沙尘重污染天气对比分析

为探究气象条件变化对宁夏沙尘重污染天气过程的影响特征,利用常规气象观测数据、NCEP再分析资料及环境空气质量数据,选取2021年1月11-14日和2021年3月14-19日两次沙尘重污染天气(分别简称“0113”过程和“0315”过程)为研究对象,基于天气形势、后向轨迹模拟及物理量场诊断等方法,对比两次过程影响系统及传输轨迹,探讨形成和维持机制.结果表明:①“0113”过程主要影响宁夏北部四市,“0315”过程影响整个宁夏,两次沙尘过程中重度及以上污染平均持续时间分别为35.0和105.2h,沙尘污染暴发阶段PM_(10)浓度平均值分别为1735和5265μg/m3.②“0113”过程为一次强度一般的锋面过境引起的沙尘重污染天气,稳定少动的青藏高压与其北侧蒙古热低压之间形成显著的气压梯度带,高空脊前多股强西北气流引起动量下传,使宁夏及上游地区大风将沙尘输送至宁夏造成重污染;“0315”过程为一次较强的典型锋面过境及蒙古气旋造成的持续沙尘重污染天气,蒙古冷高压受强盛蒙古气旋和青藏高原热低压夹击稳定少动,其西南、东南及东部与两个热低压形成气压梯度带,加之受地面冷锋过境影响,宁夏及周边地区多方向大风将沙尘向宁夏上空输送造成“0315”过程较“0113”过程污染更严重.③两次过程中沙尘均为境外和境内同时输送,“0113”过程为西北和偏西路径,传输距离长且高度较低;“0315”过程为西北、偏北和偏东路径,传输距离短且高度较高.④“0315”过程中蒙古国及我国新疆-甘肃一带负水平螺旋度中心值为“0113”过程的1.75倍,较强的辐合上升运动和西风气流将沙尘持续向宁夏上空输送并与本地沙尘叠加,上升和下沉运动交替使沙尘长时间悬浮于空中,而“0113”过程受多股强下沉气流造成沙尘迅速沉降至地面,污染快速减弱.研究显示:冷锋和蒙古气旋是宁夏沙尘重污染天气的主要影响系统,当有只冷锋过境时,上游沙尘传输高度低,到达宁夏上空沙尘粒子相对少,使宁夏沙尘重污染天气持续时间短且强度相对较弱;当伴有蒙古气旋活动时,沙尘传输高度高,到达宁夏上空沙尘粒子多,使宁夏沙尘重污染天气持续时间长、影响范围广且强度较强.

综采工作面风流及粉尘运移规律研究

为研究薄煤层综采工作面风流及粉尘运移规律,利用Fluent软件对双阳煤矿薄煤层综采工作面风流及不同产尘工序产生的粉尘运移进行数值模拟。结果表明:双阳煤矿薄煤层综采工作面风流基本规律为突然升高,再缓慢下降,最后趋于稳定;粉尘浓度出现聚集区域为移架工作区域和采煤机滚筒截割处;粉尘在人行横道空间整体扩散并不明显,在底板上存在沉积现象。为后续薄煤层综采工作面雾滴运移及降尘研究提供了前提。

汉钢冶金粉尘在烧结工序综合回收利用的研究

汉钢烧结厂通过冶金粉尘清洁运输、分类堆储及消化,建立了冶金粉尘应对调整模型,实现了钢铁企业冶金粉尘在烧结工序的综合回收利用,这一创新举措不仅有效地降低了烧结工序生产成本,实现了冶金粉尘的清洁运输,还为冶金行业提供了可持续发展的解决方案。

平煤六矿综掘面粉尘运移规律数值模拟及防治研究

针对平煤六矿综掘工作面巷道粉尘污染严重且治理效果不佳的问题,采用数值模拟的方法研究戊10-22220综掘面风流-粉尘运移规律,并据此构建了能雾化封闭主要尘源点的喷雾场。结果表明:未采取降尘措施时,掘进面迎头附近粉尘浓度达到3000 mg/m3以上,掘进机两侧和司机位置处粉尘浓度较高,而巷道后段粉尘悬浮无法及时排出;根据所得到粉尘运移规律,基于所研发的新型气水喷雾装置及水幕帘对截割尘源及逸散粉尘进行喷雾降尘,粉尘浓度得到了显著降低,降尘效率达到了85%以上。

煤矿运输巷道雾化降尘喷嘴结构研究

喷雾降尘是煤矿井下运输除尘的主要技术手段,优化喷嘴结构可有效改善喷嘴雾化效果。采用CFD软件建立了雾化降尘喷嘴模型,分析了不同因素变化对雾化效果的影响。结果表明:相比直通型喷嘴和渐扩型喷嘴,渐缩型喷嘴向外喷射距离较远,覆盖的范围更广,优选渐缩型喷嘴;相比单喷嘴形成的流场,双喷嘴的整体喷射距离和覆盖区域面积均较小,雾化性能和降尘效果较差,优选单喷嘴形式;随着喷嘴外部开口直径的增加,喷嘴喷射距离和影响范围先变大后变小,当喷嘴外部开口直径为5 mm时,雾化性能和降尘效果最强;随着喷嘴长度的增加,喷嘴喷射覆盖区域先扩大后缩小,喷嘴长度为4 mm时喷嘴喷射区域最广,雾化性能最强。

焦化厂皮带运输系统粉尘治理措施

为提高焦化厂皮带运输系统运输的稳定性,应做好粉尘治理工作。对焦化厂皮带运输系统粉尘的扩散过程与运动规律进行分析,并针对燃煤冲击、诱导风粉尘、设备故障等粉尘诱因进行探讨,提出相应的粉尘治理措施,期望可以有效控制粉尘的扩散,保障皮带运输系统的安全稳定性。