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Three-Dimensional Wind Field Retrieved from Dual-Doppler Radar Based on a Variational Method:Refinement of vertical velocity Estimates

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Advances in Atmospheric Sciences 2022年第1期39卷 145-160页

作者： Chenbin XUE Zhiying DING Xinyong SHEN Xian CHEN Key Laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China Jiangxi Meteorological Observatory Nanchang 330096China Guangdong Province Key Laboratory of Regional Numerical Weather Prediction Institute of Tropical and Marine MeteorologyCMAGuangzhou 510080China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519082China Jiangxi Institute of Land and Space Survey and Planning/Jiangxi Geomatics Center Nanchang 330000China

In this paper,a scheme of dual-Doppler radar wind analysis based on a three-dimensional variational method is proposed and performed in two ***,the horizontal wind field is simultaneously recovered through minimizing a cost function defined as a radial observation term with the standard conjugate gradient method,avoiding a weighting parameter specification *** with conventional dual-Doppler wind synthesis approaches,this variational method minimizes errors caused by interpolation from radar observation to analysis grid in the iterative solution process,which is one of the main sources of ***,through the accelerated Liebmann method,the vertical velocity is further reestimated as an extra step by solving the Poisson equation with impermeable conditions imposed at the ground and near the *** Poisson equation defined by the second derivative of the vertical velocity is derived from the mass continuity *** with the method proposed by O’Brien,this method is less sensitive to the uncertainty of the boundary conditions and has better stability and ***,the method proposed in this paper is applied to Doppler radar observation of a squall line *** is shown that the retrieved vertical wind profile agrees well with the vertical profile obtained with the velocity–azimuth display(VAD)method,and the retrieved radial velocity as well as the analyzed positive and negative velocity centers and horizontal wind shear of the squall line are in accord with radar *** is a good correspondence between the divergence field of the derived wind field and the vertical ***,the horizontal and vertical circulations within and around the squall line,as well as strong updrafts,the associated downdrafts,and associated rear inflow of the bow echo,are analyzed *** is worth mentioning that the variational method in this paper can be applied to simultaneously synthesize the three-dimensional wind fiel

关键词： dual-Doppler radar three-dimensional wind a variational method vertical velocity wind synthesis

Experimental demonstration of the coupling effect of vertical velocity on latent heat flux

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Science China Earth Sciences 2013年第4期56卷 684-692页

作者： CHEN JinBei HU YinQiao Lü ShiHua YU Ye Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Cold and Arid Regions Environment and Engineering Institute Chinese Academy of Sciences

According to the cross coupling theorem of atmospheric turbulence, latent heat flux comprises two components, a vertical humidity gradient flux and a coupling flux of vertical velocity. In this paper, observational data are employed to demonstrate and analyze the coupling effect of vertical velocity on latent heat flux. The results highlight the presence of a coupling zero-effect height. When the observational level exceeds or underlies the coupling zero-effect height, the coupling effect suppresses or enhances the latent heat flux, respectively. Above the heterogeneous terrain in the experimental region, the overall difference between the estimated and the observed latent heat fluxes decreases from 27% to 2% (for ascending flow) and from 47% to 28% (for descending flow), after compensating for gradient flux. The coupling theorem of atmospheric turbulence is well validated by our analysis, supporting a role for experimental datasets in unraveling the mysteries of atmospheric turbulence.

关键词： atmospheric surface layer (ASL) turbulent transport latent heat flux vertical velocity cross-coupling

IMPACT STUDY ON THE CALCULATION OF vertical velocity IN DIFFERENT vertical COORDINATE SYSTEMS

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Journal of Tropical Meteorology 2005年第2期11卷 187-199页

作者：李兴良陈德辉沈学顺 Chinese Academy of Meteorological Sciences

With the development of high-resolution and multi-scale unified numerical model, some of techniques about non-hydrostatic meso-scale numerical weather prediction are addressed. The impact of the vertical coordinate system is one of them. In this paper, based on a WRF (Weather Research and Forecast) model, the impact on the calculation of vertical velocity was studied with different vertical coordinates. The simulation results showed that the calculation of vertical velocity is sensitive to vertical coordinates. It is especially more evident when the resolution increased. Due to the close relationships between vertical velocity and precipitation, the difference of vertical velocity inevitably influences model’s description of precipitation. An ideal experiment exhibits that pressure gradient force computations in the pressure terrain- following coordinate are sensitive to surface pressure.

关键词： numerical prediction models coordinate system vertical velocity pressure gradient force

Performance characteristics of the airlift pump under vertical solid-water-gas flow conditions for conveying centimetric-sized coal particles

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International Journal of Coal Science & Technology 2024年第2期11卷 53-66页

作者： Parviz Enany Carsten Drebenshtedt Faculty of Mining and Special Civil Engineering Technische Universitat BergakademieGustav-Zeuner StraBe 1A09599FreibergGermany

In this study,the installation of an airlift pump with inner diameter of 102 mm and length of 5.64 m was utilized to consider the conveying process of non-spherical coal particles with density of 1340 kg/m3 and graining 25-44.5 *** test results revealed that the magnitude of increase in the solid transport rate due to the changes in the three tested parameters between compressed air velocity,submergence ratio,and feeding coal possibility was not the same,which are stand in range of 20%,75%,and 40%,***,creating the optimal airlift pump performance is highly dependent on submergence *** importantly,we measured the solid volume fraction using the method of one-way valves in order to minimize the disadvantages of conventional devices,such as fast speed camera and conductivity ring *** results confirmed that the volume fraction of the solid phase in the transfer process was always less than 12%.To validate present experimental data,the existing empirical correlations together with the theoretical equations related to the multiphase flow was *** overall agreement between the theory and experimental solid delivery results was particularly good instead of the first stage of conveying *** drawback can be corrected by omitting the role of friction and shear stress at low air income *** was also found that the model developed by Kalenik failed to predict the performance of our airlift operation in terms of the mass flow rate of the coal particles.

关键词： vertical velocity Non-spherical particle Submergence ratio Three-phase flow Churn flow Superficial velocity

Numerical Simulation and vertical Motion Control of Rolls for Variable Gauge Rolling

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Journal of Iron and Steel Research International 2015年第8期22卷 703-708页

作者： Yu ZHANG Jian TAN School of Mechatronics and Automotive Engineering Chongqing Jiaotong University Rolling Mill Chongqing Iron & Steel Co. Ltd.

The vertical motion control of the roll was studied in order to improve the accuracy in simulation of variable gauge rolling. The discretization was carried out in the transition zone of TRB according to the principle of volume invariance. Based on this assumption, the formula for time step of vertical motion of rolls was proposed and the time-displacement curve of the verti- cal motion of rolls was established. In the preliminary simulation, the time-displacement curve was used as an initial method to control the vertical motion of rolls. Based on the simulation result, the formula for vertical velocity of roll in variable gauge rolling was derived from the common rolling principle. According to the formula, reasonable vertical velocity of rolls in the subsequent simulation was determined. It can accurately control the motion of rolls along the vertical direction. The desired thickness and out- line profile of transition zone were acquired and the formula proved effective by the simulation. Further analysis shows that the di fference of thickness in the thick zone and the thin zone of TRB, length of the transition zone of TRB, radius of work rolls and rota- tion speed of rolls have a significant effect on the vertical velocity of rolls.

关键词： variable gauge rolling tailor rolled blank vertical velocity numerical simulation

A 3-D numerical simulation of the characteristics of open channel flows with submerged rigid vegetation

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Journal of Hydrodynamics 2021年第4期33卷 833-843页

作者： Jun-tao Ren Xue-fei Wu Ting Zhang School of Environment and Resource Southwest University of Science and TechnologyMianyang621010China

This paper applies the Flow-3D to investigate the impacts of different flow discharge and vegetation scenarios on the flow velocity (including the longitudinal, transverse and vertical velocities). After the verification by using experimental measurements, a sensitivity analysis is conducted for the vegetation diameter, the vegetation height and the flow discharge. For the longitudinal velocity, the greatest impact on the flow structure originates from the vegetation diameter, rather than the discharge. The vegetation height, however, determines the inflection point of the vertical distribution. Comparing the transverse velocities at two positions in the vegetated area, i.e., the upstream and the downstream, a symmetric pattern is identified along the water depth. The same pattern is also observed for the vertical velocity regardless of the flow or vegetation scenario, including both transverse and vertical fluid circulation patterns in the vegetated area. Moreover, the larger the vegetation diameter is, the more evident these patterns become. The upper circulation occurs near the vegetation canopy. These findings regarding the circulations along the transverse and vertical directions in the vegetated region shed light on the 3-D flow structure through the submerged vegetation.

关键词： Submerged rigid vegetation longitudinal velocity transverse velocity vertical velocity open channel

PV Perspective of Impacts on Downstream Extreme Rainfall Event of a Tibetan Plateau Vortex Collaborating with a Southwest China Vortex

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Advances in Atmospheric Sciences 2021年第11期38卷 1835-1851页

作者： Guanshun ZHANG Jiangyu MAO Yimin LIU Guoxiong WU State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

An extreme rainfall event occurred over the middle and lower reaches of the Yangtze Basin(MLY)during the end of June 2016,which was attributable to a Tibetan Plateau(TP)Vortex(TPV)in conjunction with a Southwest China Vortex(SWCV).The physical mechanism for this event was investigated from Potential Vorticity(PV)and omega perspectives based on MERRA-2 reanalysis *** cyclogenesis of the TPV over the northwestern TP along with the lower-tropospheric SWCV was found to involve a midtropospheric large-scale flow reconfiguration across western and eastern China with the formation of a high-amplitude Rossby ***,the eastward-moving TPV coalesced vertically with the SWCV over the eastern Sichuan Basin due to the positive vertical gradient of the TPV-related PV advection,leading the lower-tropospheric jet associated with moisture transport to intensify greatly and converge over the downstream *** merged TPV−SWCV specially facilitated the upper-tropospheric isentropic-gliding ascending motion over the *** the TPV-embedded mid-tropospheric trough migrating continuously eastward,the almost stagnant SWCV was re-separated from the overlying TPV,forming a more eastward-tilted high-PV configuration to trigger stronger ascending motion including isentropic-gliding,isentropic-displacement,and diabatic heating-related ascending components over the *** led to more intense *** PV diagnoses demonstrate that both the coalescence and subsequent re-separation processes of the TPV with the SWCV were largely dominated by horizontal PV advection and PV generation due to vertically nonuniform diabatic heating,as well as the feedback of condensation latent heating on the isentropic-displacement vertical velocity.

关键词： extreme rainfall Tibetan Plateau vortex Southwest China vortex PV vertical velocity

Mass transport of a mesoscale eddy in the South China Sea identified by a simulated passive tracer

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Journal of Oceanology and Limnology 2022年第2期40卷 389-412页

作者： Jun ZHAO Fan WANG Shan GAO Yinglin HOU Kai LIU Institute of Oceanology Chinese Academy of SciencesQingdao 266071China Key Laboratory of Ocean Circulation and Wave Chinese Academy of SciencesQingdao 266071China University of Chinese Academy of Sciences Beijing 100049China Laboratory for Ocean and Climate Dynamics Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

To quantitatively investigate the water mass transport of mesoscale eddies,the mass transport induced by a simulated anticyclonic eddy in the South China Sea was evaluated by using the Regional Ocean Modelling System(ROMS)and a built-in passive tracer *** results indicate that the eddy can trap and transport 51%of the initial water in the eddy core to 689 km from its origin during its lifetime of 100 days,with a stable loss rate of 6‰per *** propagation,there is drastic horizontal water exchange between the inside and outside of the ***,the vertical mass transport is signifi cant,and 65%of the water initially in the mixed layer of the eddy is eventually detrained into the subsurface.A tracer budget analysis of eddy shows that advection is the dominant dynamic process of transport,while the eff ect of mixing is weak,and horizontal process plays a controlling *** and vertical advection exhibit opposite patterns and strongly off set each ***,a distinct dipole pattern is found in the local velocity fi eld of the eddy,with signifi cant convergence(downwelling)and divergence(upwelling)zones in the anterior and posterior of the eddy,respectively,which is likely related to the driving mechanism of the westward propagation of the *** dipole further induces a vertical overturning cell,through which the surface water in the anterior of the eddy detrains into the subsurface by downwelling and resurface from the posterior of the eddy by upwelling and gradually spreads out of the *** temporal variability in the tracer budget is signifi cant,in which horizontal advection is *** propagation acceleration and temporal derivative of the deformation rate are highly correlated with tracer transport,suggesting the potential eff ect of the temporal instability of eddies on the eddy mass transport.

关键词： mesoscale eddy mass transport passive tracer vertical velocity mixing

Three-dimensional structure of an observed cyclonic mesoscale eddy in the Northwest Pacific and its assimilation experiment

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Acta Oceanologica Sinica 2021年第5期40卷 1-19页

作者： Jun Dai Huizan Wang Weimin Zhang Pinqiang Wang Tengling Luo College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073China

Mesoscale eddies play an important role in modulating the ocean *** previous studies on the threedimensional structure of mesoscale eddies were mainly based on composite analysis,and there are few targeted observations for individual eddies.A cyclonic eddy surveyed during an oceanographic cruise in the Northwest Pacific Ocean is investigated in this *** three-dimensional structure of this cyclonic eddy is revealed by observations and simulated by the four-dimensional variational data assimilation(4 DVAR)system combined with the Regional Ocean Modeling *** observation and assimilation results together present the characteristics of the cyclonic *** cold eddy has an obvious dual-core structure of temperature *** core is at 50–150 m and another is at 300–550 m,which both have the average temperature anomaly of approximately-3.5℃.The salinity anomaly core is between 250 m and 500 m,which is *** horizontal velocity structure is axis-asymmetric and it is enhanced on the eastern side of the cold *** the assimilation experiment,sea level anomaly,sea surface temperature,and in situ measurements are assimilated into the system,and the results of assimilation are close to the *** on the high-resolution assimilation output results,the study also diagnoses the vertical velocity in the mesoscale eddy,which reaches the maximum of approximately 10 m/*** larger vertical velocity is found to be distributed in the range of 0.5 to 1 time of the normalized radius of the *** validation of the simulation result shows that the 4 DVAR method is effective to reconstruct the three-dimensional structure of mesoscale eddy and the research is an application to study the mesoscale eddy in the Northwest Pacific by combining observation and assimilation methods.

关键词： mesoscale eddy three-dimensional structure 4DVAR assimilation vertical velocity