scholarly journals Can MERRA-2 Reanalysis Data Reproduce the Three-Dimensional Evolution Characteristics of a Typical Dust Process in East Asia? A Case Study of the Dust Event in May 2017

2020 ◽  
Vol 12 (6) ◽  
pp. 902 ◽  
Author(s):  
Wenrui Yao ◽  
Huizheng Che ◽  
Ke Gui ◽  
Yaqiang Wang ◽  
Xiaoye Zhang
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Source Area ◽  
Northwest China ◽  
Storm Event ◽  
Dust Event ◽  
Long Distance ◽  
Reanalysis Dataset

This study used the MERRA-2 reanalysis dataset and ground-based and satellite observational data to comprehensively analyze a typical dust storm event in east Asia on 2–7 May 2017 which engulfed most of China as well as ocean and Japan, and explore the accuracy and comprehensiveness of the MERRA-2 dataset in the analysis of dust processes. The results of comparison show that the description of the spatiotemporal distribution and evolution of the dust aerosols in the dust event using the MERRA-2 data is consistent with the data of AERONET, National Urban Air Quality Real-time Publishing Platform and Hamawari-8. Gobi Deserts was the most influential source area of this dust event with the highest emissions reaching 1.9 × 106 μg/m3. The vertical motion of the atmosphere can lift dust from the source area above 500 hPa. There were low-pressure troughs at 500 and 850 hPa and the winds behind and in front of the trough led to the high-altitude, long-distance transport of dust. Dust gradually affected the northwest China, north China, northeast China, and even the ocean and Japan on 2–7 May. This study demonstrates that although there is some uncertainty about the source of dust emission in the MERRA-2 model, the data accurately simulated the evolution of the dust event and analyze it comprehensively, while the accuracy of simulating the long-term evolution of dust requires further evaluation.

scholarly journals Emission, transport, and radiative effects of mineral dust from the Taklimakan and Gobi deserts: comparison of measurements and model results

2017 ◽  
Vol 17 (3) ◽  
pp. 2401-2421 ◽  
Author(s):  
Siyu Chen ◽  
Jianping Huang ◽  
Litai Kang ◽  
Hao Wang ◽  
Xiaojun Ma ◽  
...  
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Dust Concentration ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Radiative Effects ◽  
Dust Aerosols ◽  
Budget Analysis ◽  
Westerly Jets

Abstract. The Weather Research and Forecasting Model with chemistry (WRF-Chem model) was used to investigate a typical dust storm event that occurred from 18 to 23 March 2010 and swept across almost all of China, Japan, and Korea. The spatial and temporal variations in dust aerosols and the meteorological conditions over East Asia were well reproduced by the WRF-Chem model. The simulation results were used to further investigate the details of processes related to dust emission, long-range transport, and radiative effects of dust aerosols over the Taklimakan Desert (TD) and Gobi Desert (GD). The results indicated that weather conditions, topography, and surface types in dust source regions may influence dust emission, uplift height, and transport at the regional scale. The GD was located in the warm zone in advance of the cold front in this case. Rapidly warming surface temperatures and cold air advection at high levels caused strong instability in the atmosphere, which strengthened the downward momentum transported from the middle and low troposphere and caused strong surface winds. Moreover, the GD is located in a relatively flat, high-altitude region influenced by the confluence of the northern and southern westerly jets. Therefore, the GD dust particles were easily lofted to 4 km and were the primary contributor to the dust concentration over East Asia. In the dust budget analysis, the dust emission flux over the TD was 27.2 ± 4.1 µg m−2 s−1, which was similar to that over the GD (29 ± 3.6 µg m−2 s−1). However, the transport contribution of the TD dust (up to 0.8 ton d−1) to the dust sink was much smaller than that of the GD dust (up to 3.7 ton d−1) because of the complex terrain and the prevailing wind in the TD. Notably, a small amount of the TD dust (PM2.5 dust concentration of approximately 8.7 µg m−3) was lofted to above 5 km and transported over greater distances under the influence of the westerly jets. Moreover, the direct radiative forcing induced by dust was estimated to be −3 and −7 W m−2 at the top of the atmosphere, −8 and −10 W m−2 at the surface, and +5 and +3 W m−2 in the atmosphere over the TD and GD, respectively. This study provides confidence for further understanding the climate effects of the GD dust.

scholarly journals Dust Emission Inversion Using Himawari-8 AODs Over East Asia: An Extreme Dust Event in May 2017

2019 ◽  
Vol 11 (2) ◽  
pp. 446-467 ◽  
Author(s):  
Jianbing Jin ◽  
Arjo Segers ◽  
Arnold Heemink ◽  
Mayumi Yoshida ◽  
Wei Han ◽  
...  
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Dust Event

scholarly journals Emission, transport and radiative effects of mineral dust from Taklimakan and Gobi Deserts: comparison of measurements and model results

2016 ◽  
Author(s):  
Siyu Chen ◽  
Jianping Huang ◽  
Litai Kang ◽  
Hao Wang ◽  
Xiaojun Ma ◽  
...  
Keyword(s):  
East Asia ◽  
Dust Emission ◽  
Dust Concentration ◽  
Dust Particles ◽  
Storm Event ◽  
Gobi Desert ◽  
Radiative Effects ◽  
Climate Effect ◽  
Dust Aerosols ◽  
Westerly Jets

Abstract. The weather research and forecasting model with chemistry (WRF-Chem) was used to investigate a typical dust storm event that occurred from 18th to 23rd March 2010 and swept across almost all of China, Japan, and Korea. WRF-Chem captured the spatial and temporal variations in dust aerosols and the meteorological conditions over East Asia well, and the results were used to further investigate details of processes related to dust emission, long-range transport, and radiative effects of dust aerosols over the Taklimakan desert (TD) and Gobi desert (GD). Results showed that the differences of weather conditions and topography and surface types in dust source regions may lead to the differences of dust emission, uplift height and transport. The typical dust event over East Asia was classified into two main stages. In the first stage (18th–20th March), the GD was located in the warm zone in advance of a cold front. The enhanced convection increased momentum transfer in the middle and lower troposphere because of the instability in the atmosphere. Moreover, the GD is located in relatively flat, high altitude regions influenced by the confluence of the northern and southern westerly jets. Therefore, the GD dust transport was the primary contributor to the dust concentration over East Asia. The strength of the dust emission decreased greatly during the second stage (21st–23rd March). The TD dust emission contributed to the dust concentration over East Asia. Cold air was lifted over the Pamir Plateau and intruded into the Tarim basin causing a strong uplifting motion. The average TD dust emission flux was 27.2 ± 4.1 μg m−2 s−1. However, the transport contribution of the TD dust (1.1 ton day−1) to the dust sink was smaller than that of the GD dust (1.4 ton day−1) because of the complex terrain and the prevailing wind in the TD. It is noted that the TD is not the main source region in China but a small amount of the TD dust was lofted to more than 5 km and transported over greater distances under the influence of the westerly jets. Moreover, the radiative forcing induced by dust particles is estimated as −3 W m−2 and −7 W m−2 at the top of the atmosphere, −8 W m−2 and −10 W m−2 at the surface, and +5 W m−2 and +3 W m−2 in the atmosphere over the TD and GD, respectively. The study provided confidence for further understanding the climate effect of the TD and GD dust.

Saharan dust events in the Carpathian Basin (Central Europe) in 2018: provenance analyses by granulometry, XRD and SEM methods

2020 ◽  
Author(s):  
János Kovács ◽  
Nadia Gammoudi ◽  
Alex Kovács ◽  
György Varga
Keyword(s):  
Gas Adsorption ◽  
Dust Emission ◽  
Three Dimensional ◽  
Source Area ◽  
Saharan Dust ◽  
Native Plant ◽  
Hysplit Model ◽  
Native Plant Species ◽  
Source Areas ◽  
Dust Events

<p>Sediment samples were collected from Morocco, Algeria and Tunisia (as possible source sediments) and from Hungary (2018 dust events), and analyzed with the following measurements: laser diffraction, X-ray powder diffraction, automated static image analysis, and scanning electron microscopy (SEM). Similarities were expected in the results of desert-originated samples and samples collected in Hungary. In order to identify the typical dust transportation routes and possible source areas, the backward trajectories were plotted using the NOAA HYSPLIT model [1].</p><p>According to particle size distribution results, active dust emission is taking place at the location of investigated desert samples, and the samples collected in Hungary can be the particles out-blown from the source areas. The evaluated mineralogical results show that every sample contains quartz and phyllosilicates. SEM micrographs and image analyses results assume that the samples collected in Hungary are from the same source area. Using HYSPLIT application, trajectories of two analyzed dust events reveal that one desert sample, as a possible source is excluded and that the two trajectories cross each other at a junction point above North Africa (depression area between the Hoggar Mts. and Tademaït). This point can be the sought possible source location. The results in this study are convenient with those founded by Blott et al. [2] and Ahmed et al. [3]</p><p><em>Acknowledgment</em></p><p>Support of the National Research, Development and Innovation Office NKFIH KH130337 and K120213 is gratefully acknowledged.</p><p>References</p><ol><li>Draxler, RR, Rolph, GD. 2012. HYSPLIT (HYbrid Single‐Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website. NOAA Air Resources Laboratory: Silver Spring, MD. http://ready.arl.noaa.gov/HYSPLIT.php, last accessed 2019/03/20.</li> <li>Blott, S. J., Al-Dousari, A. M., Pye, K., Saye, S. E.: Three-dimensional characterization of sand grain shape and surface texture using a nitrogen gas adsorption technique. Journal of Sedimentary Research 74, 156–159‏ (2004).</li> <li>Ahmed, M., Al-Dousari, N., Al-Dousari, A.: The role of dominant perennial native plant species in controlling the mobile sand encroachment and fallen dust problem in Kuwait. Arabian Journal of Geosciences 9, 134 (2016)</li> </ol>

scholarly journals Three-Dimensional Wind-Driven Coastal Circulation past a Headland

2006 ◽  
Vol 36 (7) ◽  
pp. 1430-1438 ◽  
Author(s):  
Clinton D. Winant
Keyword(s):  
General Circulation ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Momentum Balance ◽  
Kelvin Wave ◽  
Long Distance ◽  
Barotropic Model ◽  
Significant Term ◽  
Dynamical Balance ◽  
Bottom Depth

Abstract Local velocities and the trajectories of fluid parcels forced by wind blowing over a continental shelf, in the vicinity of a headland, are described with a linear, steady, three-dimensional barotropic model. The dynamical balance that governs the transport is similar to the wind-driven general circulation, because the varying bottom depth acts in the same way as meridional variation in the rotation rate. Far from the headland the circulation is independent of alongshore position, and the transport is parallel to the coast. The alongshore pressure gradient is a significant term in the alongshore momentum balance. Near the headland, the amplitude of the circulation, including the vertical motion, is larger on the upwave side (the side toward which a Kelvin wave would travel) than on the downwave side. On the upwave side, the flow adjusts to the presence of the headland over a distance of order δEB*, where δE is the ratio of the Ekman depth to the maximum shelf depth and B* is the width of the shelf. Fluid parcels that upwell on the upwave side are drawn from deeper depths than parcels that upwell at other alongshore locations. On the downwave side the flow adjusts over a relatively long distance, of order δ−1EB*.

scholarly journals Large-Scale Dust Event in East Asia in May 2017: Dust Emission and Transport from Multiple Source Regions

SOLA ◽  
2018 ◽  
Vol 14 (0) ◽  
pp. 33-38 ◽  
Author(s):  
Yuki Minamoto ◽  
Kotaro Nakamura ◽  
Minrui Wang ◽  
Kei Kawai ◽  
Kazuma Ohara ◽  
...  
Keyword(s):  
East Asia ◽  
Large Scale ◽  
Dust Emission ◽  
Multiple Source ◽  
Dust Event ◽  
Source Regions

Isolation Performance of Intelligent Seismic Isolation System Using Air Bearing

2009 ◽  
Author(s):  
Satoshi Fujita ◽  
Keisuke Minagawa ◽  
Mitsuru Miyazaki ◽  
Go Tanaka ◽  
Toshio Omi ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Vertical Motion ◽  
Air Bearings ◽  
Natural Period ◽  
Isolation System ◽  
Vertical Excitation ◽  
Long Period ◽  
Isolation Performance

This paper describes three-dimensional isolation performance of seismic isolation system using air bearings. Long period seismic waves having predominant period of from a few seconds to a few ten seconds have recently been observed in various earthquakes. Also resonances of high-rise buildings and sloshing of petroleum tanks in consequence of long period seismic waves have been reported. Therefore the isolation systems having very long natural period or no natural period are required. In a previous paper [1], we proposed an isolation system having no natural period by using air bearings. Additionally we have already reported an introduction of the system, and have investigated horizontal motion during earthquake in the previous paper. It was confirmed by horizontal vibration experiment and simulation in the previous paper that the proposed system had good performance of isolation. However vertical motion should be investigated, because vertical motion varies horizontal frictional force. Therefore this paper describes investigation regarding vertical motion of the proposed system by experiment. At first, a vertical excitation test of the system is carried out so as to investigate vertical dynamic property. Then a three-dimensional vibration test using seismic waves is carried out so as to investigate performance of isolation against three-dimensional seismic waves.

scholarly journals New developments in the representation of Saharan dust sources in the aerosol–climate model ECHAM6-HAM2

2016 ◽  
Vol 9 (2) ◽  
pp. 765-777 ◽  
Author(s):  
Bernd Heinold ◽  
Ina Tegen ◽  
Kerstin Schepanski ◽  
Jamie R. Banks
Keyword(s):  
Climate Model ◽  
Dust Emission ◽  
Source Area ◽  
Saharan Dust ◽  
Moist Convection ◽  
Dust Source ◽  
New Developments ◽  
Infrared Imager ◽  
Dust Sources ◽  
Dust Events

Abstract. In the aerosol–climate model ECHAM6-HAM2, dust source activation (DSA) observations from Meteosat Second Generation (MSG) satellite are proposed to replace the original source area parameterization over the Sahara Desert. The new setup is tested in nudged simulations for the period 2007 to 2008. The evaluation is based on comparisons to dust emission events inferred from MSG dust index imagery, Aerosol Robotic Network (AERONET) sun photometer observations, and satellite retrievals of aerosol optical thickness (AOT).The model results agree well with AERONET measurements especially in terms of seasonal variability, and a good spatial correlation was found between model results and MSG-SEVIRI (Spinning-Enhanced Visible and InfraRed Imager) dust AOT as well as Multi-angle Imaging SpectroRadiometer (MISR) AOT. ECHAM6-HAM2 computes a more realistic geographical distribution and up to 20 % higher annual Saharan dust emissions, using the MSG-based source map. The representation of dust AOT is partly improved in the southern Sahara and Sahel. In addition, the spatial variability is increased towards a better agreement with observations depending on the season. Thus, using the MSG DSA map can help to circumvent the issue of uncertain soil input parameters.An important issue remains the need to improve the model representation of moist convection and stable nighttime conditions. Compared to sub-daily DSA information from MSG-SEVIRI and results from a regional model, ECHAM6-HAM2 notably underestimates the important fraction of morning dust events by the breakdown of the nocturnal low-level jet, while a major contribution is from afternoon-to-evening emissions.

scholarly journals Using Externally Bonded CFRP to Repair a PCCP with Broken Wires under Combined Loads

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Kejie Zhai ◽  
Hongyuan Fang ◽  
Bing Fu ◽  
Fuming Wang ◽  
Benyue Hu
Keyword(s):  
Prestressed Concrete ◽  
Three Dimensional ◽  
Soil Pressure ◽  
Long Distance ◽  
Stress Strain ◽  
Wire Breakage ◽  
Water Pipelines ◽  
Externally Bonded ◽  
Prestressed Concrete Cylinder Pipe ◽  
Three Dimensional Finite Element

Prestressed concrete cylinder pipe (PCCP) is widely used for long-distance water pipelines throughout the world. However, prestressing wire breakage is the most common form of PCCP damage. For some pipelines that cannot be shut down, a new technique for in-service PCCP repair by externally bonding the pipe with layers of carbon fiber reinforced polymer (CFRP) was proposed. A set of three-dimensional finite element models of the repaired PCCP have been proposed and implemented in the ABAQUS software, which took into account the soil pressure, the weight of the PCCP, the weight of the water, and the hydrostatic pressure. The stress–strain features of the PCCP repaired with CFRP of various thicknesses were analyzed. The stress–strain features of different wire breakage rates for the repaired PCCP were also analyzed. The results showed that the strains and stresses decreased at the springline if the PCCP was repaired with CFRP, which improved the operation of the PCCP. It has been found that the wire breakage rates had a significant effect on the strains and stresses of each PCCP component, but CFRP failed to reach its potential tensile strength when other materials were broken.

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