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Assimilating Surface Observations in a Four-Dimensional Variational Doppler Radar Data Assimilation System to Improve the Analysis and Forecast of a Squall Line Case

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Advances in Atmospheric Sciences 2016年第10期33卷 1106-1119页

作者： Xingchao CHEN Kun ZHAO Juanzhen SUN Bowen ZHOU Wen-chau lee Key Laboratory for Mesoscale Severe Weather/MOE and School of Atmospheric Science Nanjing UniversityNanjing 210046China National Center for Atmospheric Research BoulderColorado 80301USA

This paper examines how assimilating surface observations can improve the analysis and forecast ability of a four- dimensional Variational Doppler Radar Analysis System （VDRAS）. Observed surface temperature and winds are assimilated together with radar radial velocity and reflectivity into a convection-permitting model using the VDRAS four-dimensional variational （4DVAR） data assimilation system. A squall-line case observed during a field campaign is selected to investigate the performance of the technique. A single observation experiment shows that assimilating surface observations can influence the analyzed fields in both the horizontal and vertical directions. The surface-based cold pool, divergence and gust front of the squall line are all strengthened through the assimilation of the single surface observation. Three experiments--assimilating radar data only, assimilating radar data with surface data blended in a mesoscale background, and assimilating both radar and surface observations with a 4DVAR cost function--are conducted to examine the impact of the surface data assimilation. Independent surface and wind profiler observations are used for verification. The result shows that the analysis and forecast are improved when surface observations are assimilated in addition to radar observations. It is also shown that the additional surface data can help improve the analysis and forecast at low levels. Surface and low-level features of the squall line-- including the surface warm inflow, cold pool, gust front, and low-level wind--are much closer to the observations after assimilating the surface data in VDRAS.

关键词： VDRAS 4-D data assimilation radar data surface data squall line

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Assimilation of GBVTD-derived Winds from Single-Doppler Radar for Short-term Forecasting of Super Typhoon Saomai （0608） at Landfall

Assimilation of GBVTD-derived Winds from Single-Doppler Rada...

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第七届全国优秀青年气象科技工作者学术研讨会

作者： Wen-chau lee Earth Observing Laboratory National Center for Atmospheric Research

A single-Doppler wind retrieval method called the Ground-Based Velocity-Track Display technique （GBVTD） has been developed in recent years to retrieve horizontal circulations of tropical cyclones when they are within the range of coastal Doppler radars. The technique is able to retrieve axisymmetric tangential and radial winds, asymmetric tangential winds for wavenumbers 1 through 3, and the along-beam mean winds within the tropical cyclones. It has been successfully applied to several typhoon cases for the tropical cyclone monitoring and warning. This study explores, for the first time, the assimilation of GBVTD-retrieved winds into a tropical cyclone prediction model, and examines its impact relative to that of directly assimilated radial velocity data. Super Typhoon Saomai （2006）, the most intense landfalling typhoon ever recorded in China, is chosen as the test case, and data from the coastal operational radar at Wenzhou, China are used. The ARPS 3DVAR/cloud analysis system is used to assimilate either the radial velocity data directly or the GBVTD-retrieved winds, at 30-min intervals for 2 hours. A control forecast is also made using an initial condition from the Japan Meteorological Agency mesoscale reanalysis. The assimilation of the GBVTD-retrieved winds results in much improved structure and intensity analyses of Saomai compared to those in the JMA （Japan Meteorological Agency） mesoscale reanalysis as well as that assimilating radial velocity （Vr） data directly. The ability of the GBVTD method in obtaining complete vortex circulations in the inner-core region is the primary reason for its superior performance over direct assimilation of Vr data;for the latter, the azimuthal data coverage is often incomplete. With the improvement in the initial conditions, the subsequent forecasts of typhoon intensity, track and precipitation are also improved. The improvements to both track and intensity predictions persist over a 12-hour forecast period, which is mostly af

关键词： Landfalling typhoon GBVTD assimilation

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Can we omit systematic biopsies in patients undergoing MRI fusion-targeted prostate biopsies?

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Asian Journal of Andrology 2023年第1期25卷 43-49页

作者： Jeffrey J Leow Soon Hock Koh Marcus WL Chow Wayren Loke Rolando Salada Seok Kwan Hong Yuyi Yeow chau Hung lee Cher Heng Tan Teck Wei Tan Department of Urology Tan Tock Seng HospitalSingapore 308433Singapore lee Kong Chian School of Medicine Nanyang Technological UniversitySingapore 308232Singapore Department of Diagnostic Radiology Tan Tock Seng HospitalSingapore 308433Singapore

Magnetic resonance imaging(MRI)-targeted prostate biopsy is the recommended investigation in men with suspicious lesion(s)on *** role of concurrent systematic in addition to targeted biopsies is currently *** our prospectively maintained database,we identified men with at least one Prostate Imaging-Reporting and Data System(PI-RADS)≥3 lesion who underwent targeted and/or systematic biopsies from May 2016 to May *** significant prostate cancer(csPCa)was defined as any Gleason grade group≥2 *** 545 patients who underwent MRI fusion-targeted biopsy,222(40.7%)were biopsy naïve,247(45.3%)had previous prostate biopsy(s),and 76(13.9%)had known prostate cancer undergoing active *** cancer was more commonly found in biopsy-naïve men(63.5%)and those on active surveillance(68.4%)compared to those who had previous biopsies(35.2%;both P<0.001).Systematic biopsies provided an incremental 10.4%detection of csPCa among biopsy-naïve patients,versus an incremental 2.4%among those who had prior negative *** regression found age(odds ratio[OR]=1.03,P=0.03),prostate-specific antigen(PSA)density≥0.15 ng ml^(−2)(OR=3.24,P<0.001),prostate health index(PHI)≥35(OR=2.43,P=0.006),higher PI-RADS score(vs PI-RADS 3;OR=4.59 for PI-RADS 4,and OR=9.91 for PI-RADS 5;both P<0.001)and target lesion volume-to-prostate volume ratio≥0.10(OR=5.26,P=0.013)were significantly associated with csPCa detection on targeted *** conclusion,for men undergoing MRI fusion-targeted prostate biopsies,systematic biopsies should not be omitted given its incremental value to targeted biopsies *** factors such as PSA density≥0.15 ng ml^(−2),PHI≥35,higher PI-RADS score,and target lesion volume-to-prostate volume ratio≥0.10 can help identify men at higher risk of csPCa.

关键词： prostate biopsy prostate cancer prostate health index prostate-specific antigen software fusion Uronav

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Reaction between Alkaline Metal Ions and ASR Reactive Aggregate and Behavior of Na＊ and K＊ in Cement Paste Replaced by Li＊

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Journal of Civil Engineering and Architecture 2013年第9期7卷 1056-1062页

作者： Wei Chien Wang Chih Chien Liu chau lee Department of Civil Engineering Chung Yuan Christian University Chung Li 32023 Taiwan R. O. C. Department of Civil Engineering R.O.C. Military Academy Fengshan 83059 Taiwan R.O.C. Department of Civil Engineering National Central University Chung Li 32001 Taiwan R.O.C.

This paper studies the reaction between alkaline metal ions Li＋, Na＋ and K＋ and ASR （alkali-silica reaction） reactive aggregates to determine whether Li＋ can substitute Na＋ and K＋ that are unified in cement paste. Reactive aggregates use meta-sandstone from eastern Taiwan and Pyrex glass. Non-reactive aggregates use siliceous sand. The results show that the dissolved amount of SiO2 is lower when the reactive aggregates are immersed in an 80 ℃1 N LiOH＇H20 solution than in NaOH and KOH solutions. The reduced amounts of OH and Li＋ in the solution are also higher than those in the NaOH and KOH solutions. These results reveal that reactive SiO2 can react with LiOH to form a reactant with low water solubility. When the powder of the cement paste is immersed in an 80 ℃ 1 N LiOH-H2O solution, the amounts of free Na＋ and K＋ in the solution are higher than those in water. The increased amount increases with the duration of immersion. The amount of Li＋ in the solution also decreases with the duration of immersion. These results reveal that Li＋ can substitute Na＋ and K＋ that are unified in cement paste, which indicates that ASR can be prevented with the existence of Li＋.

关键词： Alkali-silica reaction lithium reactive aggregate paste.

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Recent Progress in Dual-Polarization Radar Research and Applications in China

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Advances in Atmospheric Sciences 2019年第9期36卷 961-974页

作者： Kun ZHAO Hao HUANG Mingjun WANG Wen-chau lee Gang CHEN Long WEN Jing WEN Guifu ZHANG Ming XUE Zhengwei YANG Liping LIU Chong WU Zhiqun HU Sheng CHEN Key Laboratory of Mesoscale Severe Weather of Ministry of Education and School of Atmospheric Sciences Nanjing University163 Xianlin RoadNanjing 210023China State Key Laboratory of Severe Weather and Joint Center for Atmospheric Radar Research of China Meteorological Administration and Nanjing University Chinese Academy of Meteorological SciencesBeijing 100081China National Center for Atmospheric Research BoulderColorado 80301USA School of Meteorology and Advanced Radar Research Center University of OklahomaNormanOklahoma 73019USA School of Atmospheric Sciences and Guangdong Province Key Laboratory for Climate Change and Natural Disaster StudiesSun Yat-sen UniversityGuangzhou 510006China

Dual-polarization(dual-pol)radar can measure additional parameters that provide more microphysical information of precipitation systems than those provided by conventional Doppler *** dual-pol parameters have been successfully utilized to investigate precipitation microphysics and improve radar quantitative precipitation estimation(QPE).The recent progress in dual-pol radar research and applications in China is summarized in four ***,the characteristics of several representative dual-pol radars are *** approaches have been developed for radar data quality control,including calibration,attenuation correction,calculation of specific differential phase shift,and identification and removal of non-meteorological *** dual-pol radar measurements,the microphysical characteristics derived from raindrop size distribution retrieval,hydrometeor classification,and QPE is better understood in *** limited number of studies in China that have sought to use dual-pol radar data to validate the microphysical parameterization and initialization of numerical models and assimilate dual-pol data into numerical models are *** challenges of applying dual-pol data in numerical models and emerging technologies that may make significant impacts on the field of radar meteorology are discussed.

关键词： dual-polarization radar quantitative precipitation estimation precipitation microphysics drop size distribution numerical model

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RADAR OBSERVATION OF PRECIPITATION ASYMMETRIES IN TROPICAL CYCLONES MAKING LANDFALL ON EAST CHINA COAST

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Tropical Cyclone Research and Review 2013年第2期2卷 81-95页

作者： DAN WU KUN ZHAO BEN JONG-DAO JOU WEN-chau lee Shanghai Typhoon Institute/China Meteorological Administration Key Laboratory for Mesoscale Severe Weather/MOE and School of Atmospheric Science Nanjing University Department of Atmospheric Sciences National Taiwan University The National Center for Atmospheric Research

This study explores,for the first time,the asymmetric distribution of precipitation in tropical cyclones(TCs) making landfall along east China coast using reflectivity data collected from coastal Doppler radars at China's Mainland and *** TCs(Saomai,Khanun,Wipha,Matsa,Rananim and Krosa) from 2004 to 2007 are *** temporal and spatial evolution of these TCs’ inner and outer core asymmetric precipitation patterns before and after landfall is *** radius of inner-core region is a function of the size of a TC apart from a fixed radius(100 km) adopted in previous *** six TCs possessed distinct asymmetric precipitation patterns between the inner-and outer-core *** amplitude of asymmetry decreases with the increasing TC intensity and it displays an ascending(descending) trend in the inner(outer) *** the inner-core region,the heavy rainfall with reflectivity factor above 40 d BZ tends to locate at the downshear side before *** cases have precipitation maxima on the downshear left side,in agreement with previous *** TCs approaching land(~ 2 hr before landfall),their precipitation maxima generally shift to the front quadrant of the motion partly due to the interaction of TC with the land *** the outer-core region,the precipitation maxima occur in the front quadrant of the motion in five of the six cases before *** landfall,the precipitation maxima shift from the right-front quadrant clockwisely to the right-rear quadrant of the motion collocated well with the mountainous areas along the coast,which indicates the impact of topography forcing on the precipitation *** study illustrated how the precipitation asymmetry in the inner-and outer-core at different stages of TC landfall is affected by storm motion,vertical wind shear and topography.

关键词： landfalling tropical cyclone asymmetric precipitation distribution East China

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第2章大气观测系统100年进步

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气象科技进展 2019年第S1期9卷 18-39页

作者：杰弗里·斯蒂斯 DARREL BAUMGARDNER JULIE HAGGERTY R.MICHAEL HARDESTY WEN-chau lee DONALD LENSCHOW PETER PILEWSKIE PAUL L.SMITH MATTHIAS STEINER HOLGER V?MEL 贾朋群李婧华 NCAR 微滴测量科技公司科罗拉多大学 NOAA/ESRL 南达科他矿业理工学院

虽然在美国气象学会于1919年成立之前,大气观测系统已经是气象的重要组成部分,过去的100年里,无论是观测的数量还是种类都获得了稳定增加。本文给出了观测系统研发的案例,诠释这些系统如何促成了科学发现。这些案例包括了与边界层、高... 详细信息

虽然在美国气象学会于1919年成立之前,大气观测系统已经是气象的重要组成部分,过去的100年里,无论是观测的数量还是种类都获得了稳定增加。本文给出了观测系统研发的案例,诠释这些系统如何促成了科学发现。这些案例包括了与边界层、高空、云和降水以及太阳和地球辐射相关的观测系统。对应用广泛的特殊观测系统,例如雷达、光达和研究用飞机等进行了讨论,并给出在天气和气候预报中应用的个例。这些个例中还包含了臭氧和二氧化碳等特殊的化学观测。观测系统的信息源,包括本文集其他章节涉及内容,也进行了讨论。过去100年大气观测系统的特征,是社会对天气观测的需求与大气过程基本气象研究需求之间的协同。在后半程里,观测系统的改进得到数值模式对更高分辨率数据、长期观测和更好的全球覆盖等不断增长需求的推进。这也带来数据获取和获得来自不断增加的各种观测系统类型和观测网的融合数据的需求,这样的趋势或将持续。

关键词：观测系统美国气象学会气象研究地球辐射全球覆盖天气观测长期观测信息源

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Comparison of Flux-Switching Machines With and Without Permanent Magnets

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Chinese Journal of Electrical Engineering 2015年第1期1卷 78-84页

作者： Christopher H.T.lee K.T.chau C.C.Chan Department of Electrical and Electronic Engineering The University of Hong KongHong KongChina

In this paper,three advanced flux-switching(FS)machines,namely the radial-field flux-switching permanent-magnet(RF-FSPM)machine,the radial-field flux-switching DC-field(RF-FSDC)machine,and the axial-field FSDC(AF-FSDC)machine are quantitatively *** the installation of the high-energy-density PM materials,the RF-FSPM machine can definitely provide the superior torque performances as compared to its magnetless ***,the PM machines suffer from two major fundamental problems,namely the high material costs,and the uncontrollable flux *** utilizing the concept of axial-field structure,the AF-FSDC machine can offer comparable torque performance as the RF-FSPM ***,with the consideration of the cost-effectiveness and the control flexibility,the magnetless AF-FSDC machine has exhibited promising potential in various applications.

关键词： Flux-switching magnetless radial-field axial-field cost-effectiveness

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Uniqueness, scale, and resolution issues in groundwater model parameter identification

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Water Science and Engineering 2015年第3期8卷 175-194页

作者： Tian-chyi J.Yeh De-qiang Mao Yuan-yuan Zha Jet-chau Wen Li Wan Kuo-chin Hsu Cheng-haw lee Department of Hydrology and Water Resources The University of Arizona Department of Resources Engineering National Cheng Kung University Department of Geophysics Colorado School of Mines State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan University Department of Safety Health and Environmental Engineering National Yunlin University of Science and Technology Research Center for Soil & Water Resources and Natural Disaster Prevention National Yunlin University of Science and Technology

This paper first visits uniqueness, scale, and resolution issues in groundwater flow forward modeling problems. It then makes the point that non-unique solutions to groundwater flow inverse problems arise from a lack of information necessary to make the problems well defined. Subsequently, it presents the necessary conditions for a well-defined inverse problem. They are full specifications of （1） flux boundaries and sources/sinks, and （2） heads everywhere in the domain at at least three times （one of which is t = 0）, with head change everywhere at those times being nonzero for transient flow. Numerical experiments are presented to corroborate the fact that, once the necessary conditions are met, the inverse problem has a unique solution. We also demonstrate that measurement noise, instability, and sensitivity are issues related to solution techniques rather than the inverse problems themselves. In addition, we show that a mathematically well-defined inverse problem, based on an equivalent homogeneous or a layered conceptual model, may yield physically incorrect and scenario-dependent parameter values. These issues are attributed to inconsistency between the scale of the head observed and that implied by these models. Such issues can be reduced only if a sufficiently large number of observation wells are used in the equivalent homogeneous domain or each layer. With a large number of wells, we then show that increase in parameterization can lead to a higher-resolution depiction of heterogeneity if an appropriate inverse methodology is used. Furthermore, we illustrate that, using the same number of wells, a highly parameterized model in conjunction with hydraulic tomography can yield better characterization of the aquifer and minimize the scale and scenario-dependent problems. Lastly, benefits of the highly parameterized model and hydraulic tomography are tested according to their ability to improve predictions of aquifer responses induced by independent stresses not u

关键词： Uniqueness Scale Resolution Forward and inverse problems Hydraulic tomography

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Tuning the inhomogeneous charge transport in ZnO interfaces for ultrahigh on/off ratio top-gated field-effect-transistor arrays

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Nano Research 2020年第11期13卷 3033-3040页

作者： Thanh Luan Phan Dinh Loc Duong Tuan Khanh chau Sidi Fan Won Tae Kang Thi Suong Le Hyun Yong Song Linfeng Sun Van Tu Vu Min Ji lee Quoc An Vu Young Hee lee Woo Jong Yu Department of Electrical and Computer Engineering Sungkyunkwan UniversitySuwon16419Republic of Korea Center for Integrated Nanostructure Physics(CINAP) Institute for Basic Science(IBS)Suwon16419Republic of Korea Department of Energy Science Sungkyunkwan UniversitySuwon16419Republic of Korea Department of Physics Sungkyunkwan UniversitySuwon16419Republic of Korea

The interface between oxide/oxide layers shows an inhomogeneous charge transport behavior,which reveals a high conductivity owing to *** typical example is the hetero-interface between ZnO film and other wide band gap oxides(e.g.,Al_(2)O_(3),TiO_(2),and HfO_(2)).It is thus quite evident that the ZnO/other oxides hetero-interface contains high density electron carriers effectively screening the gate-induced electric ***,an extremely weak gate modulation in ZnO film was showed,resulting in very low on/off ratio of 1.69 in top-gate field-effect-transistor(TG-FET)***,to extend the usage of ZnO TG-FET is not quite possible toward further practical ***,we clarified the correlation of inhomogeneous region in oxide/oxide hetero-junction by systematically *** work suggests that a self-assembly of molecules(SAM)buffer layer is suitable for tuning the inhomogeneous charge transport in ZnO film,which not only reduces the interface trap density,but also effectively enhances the gate electric field modulation at the *** further report the robust fabrication of TG-FET arrays based on ZnO thin film,using an ultra-thin alkylphosphonic acid molecule monolayer as buffer *** device demonstrates a pronounced ultrahigh on/off ratio of≥10^(8),which is 8-order of magnitude higher than that of a device without buffer *** the highly reliable arrays,our device exhibits a high yield of over 93%with an average on/off ratio of^10^(7) across the entire wafer scale,mobility(18.5 cm^(2)/(V·s)),an extended bias-stressing(~2,000 s)and long-stability(~150 days)under ambient conditions.

关键词： zinc oxides thin-film field-effect-transistor self-assembly molecule inhomogeneous charge transport interface engineering

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