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1.
本文采用中尺度数值预报模式GRAPES_Meso V3.3.2.5版本以及NECP的GFS资料,分别选用模式中不同陆面参数化方案(SLAB、LSM、NOAH)对2013年9月14-17日新疆强降水过程进行数值模拟试验,模拟的结果表明:陆面方案对主要雨带的落区和大致走向影响并不大,但对降强度的模拟还是敏感的,耦合陆面方案比不耦合陆面方案的模拟效果更接近实况;不同陆面方案模拟的降水量存在一定差异,它们对降水中心落点、强度以及类型方面各有所长;在各种试验的综合比较中,NOAH方案较其他方案的模拟结果显得更稳定与合理。  相似文献   

2.
马红云  郭品文  宋洁 《大气科学》2009,33(3):557-567
利用WRF模式, 分别选用不同陆面参数化方案 (SLAB、 RUC、 NOAH、 UCM) 对2007年7月7~8日的江淮暴雨进行数值模拟试验, 模拟结果的对比分析表明: 虽然主要雨带的基本位置和大致走向受陆面方案的影响并不大, 但是降水强度的分布对陆面物理过程是敏感的, 耦合陆面方案比不耦合陆面方案的模拟效果更接近实况; 不同陆面方案模拟的降水量均较实况偏小, 然而由于考虑的要素和物理过程存在一定差异, 它们对降水的中心落点、 雨量值、 降水日变化、 降水类型以及降水条件的模拟各有所长; 特别值得指出, TRMM资料与4种方案的模拟结果均反映出本次降水日变化过程中夜间的峰值特征, 这是短时降水 (1~3 h) 和持续性降水 (≥6 h) 的综合反映, 而凌晨后的降水则主要由持续性降水造成; 在各种试验的综合比较中, NOAH方案较其他方案的模拟结果显得更稳定与合理, UCM方案针对城市下垫面的模拟有一定优越性。  相似文献   

3.
两次暴雨过程模拟对陆面参数化方案的敏感性研究   总被引:1,自引:0,他引:1  
陈海山  倪悦  苏源 《气象学报》2014,72(1):79-99
选取发生在江西和福建境内的两次暴雨个例,利用NCEP再分析资料在对暴雨发生前、后的环境场和物理量场进行诊断和对比分析的基础上,采用中尺度模式WRF V3.3,通过数值模拟探讨了陆面过程对两次暴雨过程的可能影响及其相关的物理过程。结果表明,2012年5月12日江西大暴雨主要受大尺度环流和中尺度天气系统影响,具有范围大、持续时间长等特点,属于大尺度降水为主的暴雨;而2011年8月23日福建暴雨发生在副热带高压控制下的午后,局地下垫面强烈的感热和潜热通量使低层大气不稳定性增强,触发了此次对流性降水为主的暴雨。通过资料诊断分析,可以判断陆面过程对福建暴雨个例的影响程度明显强于江西暴雨个例。通过关闭地表通量试验发现,陆面过程对暴雨模拟十分重要,尤其是对于该个例中对流性降水的发生起到关键性的作用。通过陆面参数化方案的敏感性试验发现,两次暴雨过程对陆面参数化方案均较为敏感。江西暴雨对陆面过程的敏感性主要体现在对流降水的模拟上,而福建暴雨则体现在大尺度降水的模拟方面,即福建暴雨对陆面参数化方案的敏感性强于江西暴雨。敏感性产生机制与降水类型关系紧密,大尺度降水对陆面过程的敏感性主要来源于不同参数化模拟的中高空对流系统的差异,而对流降水的敏感性则与不同参数化模拟的地表通量的差异有关。通过陆面参数的扰动试验进一步发现,相比于地表粗糙度和最小叶孔阻抗,土壤孔隙度和地表反照率则是影响对流降水对陆面过程敏感的关键因子,这在本质上与地表通量是否受到扰动有关。地表通量较风场而言,受扰动引起变化的空间范围广、时间响应快,变化具有明显规律性。所得结果可为深入理解陆面过程影响暴雨等天气过程和改进数值模式对暴雨的模拟能力提供一定的参考。  相似文献   

4.
GFS物理过程包在GRAPES区域模式中的实施及改进:单柱试验   总被引:3,自引:2,他引:1  
黄伟  张旭  Jian-Wen Bao  陈葆德 《大气科学》2018,42(6):1219-1234
将NCEP的中期全球预报系统(GFS)整套物理过程包引入GRAPES区域模式,并利用美国ARM计划(Atmospheric Radiation Measurement Program)南部大平原外场1997年夏加强观测资料,对GRAPES模式中原有物理过程和GFS物理过程进行了单柱试验的测试和比较,评估了两组物理过程的模拟性能。单柱试验结果表明GFS试验模拟的位温和水汽混合比演变更为准确;到地短波和长波辐射的误差更小;其模拟的地面向上潜热通量与观测更为接近,而原物理过程试验的感热偏大;GFS试验对2 m气温最高和最低值的模拟也比原有物理过程更接近观测。进一步分析降水的模拟发现,两组物理过程对强降水过程均有很好的预报能力,但对中等强度降水存在漏报或者发生时间偏晚的倾向,此外还存在对小雨的空报。在3个降水事件的模拟中,GFS试验模拟的降水误差小于原物理过程试验。最后还对两组试验中明显的降水过程漏报和降水延迟进行了分析,对GFS物理过程包中对流参数化的对流触发方式的修改,可改进此次降水的模拟,进而通过更准确的反馈过程,改善对大尺度场的模拟。  相似文献   

5.
The regional climate model (RegCM4) is customized for 10-year climate simulation over Indian region through sensitivity studies on cumulus convection and land surface parameterization schemes. The model is configured over 30° E–120° E and 15° S–45° N at 30-km horizontal resolution with 23 vertical levels. Six 10-year (1991–2000) simulations are conducted with the combinations of two land surface schemes (BATS, CLM3.5) and three cumulus convection schemes (Kuo, Grell, MIT). The simulated annual and seasonal climatology of surface temperature and precipitation are compared with CRU observations. The interannual variability of these two parameters is also analyzed. The results indicate that the model simulated climatology is sensitive to the convection as well as land surface parameterization. The analysis of surface temperature (precipitation) climatology indicates that the model with CLM produces warmer (dryer) climatology, particularly over India. The warmer (dryer) climatology is due to the higher sensible heat flux (lower evapotranspiration) in CLM. The model with MIT convection scheme simulated wetter and warmer climatology (higher precipitation and temperature) with smaller Bowen ratio over southern India compared to that with the Grell and Kuo schemes. This indicates that a land surface scheme produces warmer but drier climatology with sensible heating contributing to warming where as a convection scheme warmer but wetter climatology with latent heat contributing to warming. The climatology of surface temperature over India is better simulated by the model with BATS land surface model in combination with MIT convection scheme while the precipitation climatology is better simulated with BATS land surface model in combination with Grell convection scheme. Overall, the modeling system with the combination of Grell convection and BATS land surface scheme provides better climate simulation over the Indian region.  相似文献   

6.
陆面过程参数化对太湖地区雷暴过程模拟的影响   总被引:1,自引:1,他引:0       下载免费PDF全文
以2010年8月发生在太湖地区的一次雷暴过程为例,利用WRF模式进行48 h的短期天气模拟,分析两个陆面参数化方案(Noah方案和RUC方案)对雷暴过程模拟的影响。对比模式结果与实况降水以及太湖地区两个站点的近地面要素表明:雷暴过程对陆面参数化方案的选取较为敏感,不同陆面参数化方案可影响雷暴发生的时间、地点及强度,两种方案的降水中心值差达40 mm以上,其中Noah方案所模拟的降水与实况更为接近。通过对两个方案模拟的物理量场的对比分析发现,RUC方案中对流发展滞后于Noah方案2 h;这表明陆面过程对雷暴等中尺度对流过程有显著的反馈作用,不同陆面参数化方案的使用影响雷暴发生的动力和热力作用,并改变雷暴的时空分布特征。陆面过程通过改变地面热通量输送影响边界层结构,使得水平和垂直方向上的风和温度等发生变化并产生辐合辐散,进而影响对流的启动时间和对流发展强度。由于对不同植被的参数化处理的差异,Noah方案对下垫面特征的描述能力优于RUC方案,尤其是对城市下垫面的处理,这也使得之后该方案模拟的雷暴发生时间更加接近于实况且雷暴过程更加强烈。  相似文献   

7.
In this study,two convective-stratiform rainfall partitioning schemes are evaluated using precipitation and cloud statistics for different rainfall types categorized by applying surface rainfall equation on grid-scale data from a two-dimensional cloud-resolving model simulation.One scheme is based on surface rainfall intensity whereas the other is based on cloud content information.The model is largely forced by the large-scale vertical velocity derived from the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment(TOGA COARE).The results reveal that over 40% of convective rainfall is associated with water vapor divergence,which primarily comes from the rainfall type with local atmospheric drying and water hydrometeor loss/convergence,caused by precipitation and evaporation of rain.More than 40% of stratiform rainfall is related to water vapor convergence,which largely comes from the rainfall type with local atmospheric moistening and hydrometeor loss/convergence attributable to water clouds through precipitation and the evaporation of rain and ice clouds through the conversion from ice hydrometeor to water hydrometeor.This implies that the separation methods based on surface rainfall and cloud content may not clearly separate convective and stratiform rainfall.  相似文献   

8.
张瑛  肖安  马力  王欢  马中元  周芳 《气象》2011,37(9):1060-1069
利用WRF模式与4个陆面过程的耦合,对2010年6月19—20日的暴雨过程进行了数值模拟,并分析陆面过程对暴雨强度和范围的敏感性。结果显示:WRF耦合4个陆面过程模拟的雨带和实况分布一致,均为东西向的雨带形状,且均预报出与实况资料相似的强降水中心。在无陆面方案情况下,强降水中心的位置、范围、强度等都发生明显变化。另外地表径流预报量和降水趋势表现一致,由于土壤含水量趋于饱和,多余的降水分配给地表径流,这种剧增的地表径流也是洪水暴涨、水位上升的重要原因。在较湿的土壤状况下,由于净辐射增长,有利于产生厚度更小的边界层高度以及更大的地表向上潜热通量,这也是导致本次降水过程异常增幅的一个重要原因。  相似文献   

9.
利用WRF模式选用不同的边界层参数化方案 (YSU、MRF) 结合三种陆面过程方案 (RUC、SLAB、Noah) , 模拟了2011年5月1~3日的四川东部暴雨过程, 对不同参数化方案结合不同陆面过程结果进行对比试验基础上发现, 模式对24h降水落区及强度有较强预报能力, 但对单站小时降水分布的预报能力还需改进;不同边界层方案与陆面过程的对比试验说明降水对于边界层物理过程有一定敏感性, 各试验的差异主要体现在对暴雨中心雨强以及降水峰值强度和峰值出现时段的预报上;WRF模式基本上能够模拟出边界层要素日变化特征。   相似文献   

10.
基于1980—2015年6—8月CWRF模式(Climate-Weather Research and Forecasting model)14种方案的模拟结果和全国逐日降水观测资料,对比了Q-lin,Q-tri,RQ-lin,RQ-tri,SSP-lin和CDFt 6种误差订正方法对CWRF模式控制化方案(C1)模拟中国东部夏季日极端降水的订正效果,以CWRF模式14种方案日极端降水的模拟效果排名为基础,对比了模拟效果较好的4种方案集合、模拟较差的4种方案集合以及14种方案集合的订正效果,选出相对较好的订正方案进一步评估其成员集合后订正和成员分别订正后再集合的订正效果,结果表明:采用6种误差订正方法均可明显减少日极端降水模拟误差,其中RQ-lin方法订正效果最佳。CWRF模式对中国东部的极端降水指数均表现出较好的模拟能力,不同参数化集合方案得到14种方案成员先订正再集合与观测日极端降水平均值最为接近,研究结果对于改进模拟结果、提高其预测能力有重要应用价值。  相似文献   

11.
Tropical monsoon circulations exhibit substantial interannual variability. Establishing clear links between this variability and the slowly varying boundary forcing (sea surface temperatures, SSTs, and land surface conditions) has proved difficult. For example, no clear relationships have been found between SST anomalies associated with El Nino/La Nina events and monsoon rainfall. Despite much research over the past 50 years, there are still questions regarding how different components of the land-atmosphere-ocean system contribute to tropical monsoon variability. This study examines the question of land-surface-atmosphere interactions in large-scale tropical convection and their role in rainfall interannual variability. The analysis method is based on a conceptual model of convection energetics applied every day of the simulation at the grid points within the region of interest. This allows for a distinction between the frequency and the characteristic energy and water cycle of these events. With two ensembles of five and three experiments in which different land-surface schemes are used, the relation between land-surface processes and variation of the frequency of convection is studied. It has been found in this modeling study that the formulation of land surface schemes may be important for both the simulation of mean tropical precipitation and its interannual variability by way of the frequency of convective events. Linked to this is an increased response of hydrological cycle over land to SSTAs. Numerous studies have suggested that large-scale factors, such as SST, are the dominant control. However the influence of surface processes depends on the areal extent and distance that separates the region from the ocean. The fact that differences between tropical regions decreases as convection intensifies strengthens this hypothesis. The conclusion is that it is inappropriate to separate the causes of interannual variability between SSTAs and land-surface anomalies to explain precipitation variations as land surface processes play a significant mediating role in the relationship between SSTs and monsoon strength. However there remains the possibility that a substantial portion of variability is due to dynamical processes internal to the atmosphere. Determining the relative roles of internal and lower boundary forcing processes in producing interannual variations in the tropical climate is a major objective of future research.  相似文献   

12.
不同辐射传输方案对中尺度降水影响的对比分析   总被引:5,自引:3,他引:5       下载免费PDF全文
在MM5非静力稳定中尺度气象模式中引进了建立在δ-4流近似和相关-k分布基础上的对云水、雨水、冰晶和霰的辐射特性进行详细描述的辐射传输方案。新建立的辐射传输方案和MM5中原有的辐射传输方案在华南暴雨中的模拟结果相互比较,并与天气实况的对比表明:辐射在中尺度暴雨中起着重要的作用;辐射传输方案对云辐射特性描述的准确程度对于地面降水影响是明显的;不同的辐射传输方案对地面降水的影响存在较大的差异,并且这些差异在白天比在夜间明显;辐射传输过程对地面降水影响的差异主要表现在降水中心上,而对降水的地理分布改变很小;相对而言,不同的辐射传输方案之间对短波描述的差异对地面降水的影响明显,而对长波描述差异的影响不大;新辐射传输方案能够在一定程度上改进MM5对中尺度降水的模拟能力。  相似文献   

13.
Using the Weather Research and Forecasting(WRF)model with two different microphysics schemes,the Predicted Particle Properties(P3)and the Morrison double-moment parameterizations,we simulated a stratiform rainfall event on 20–21 April 2010.The simulation output was compared with precipitation and aircraft observations.The aircraft-observed moderate-rimed dendrites and plates indicated that riming contributed significantly to ice particle growth at the mature precipitation stage.Observations of dendrite aggregation and capped columns suggested that aggregation coexisted with deposition or riming and played an important role in producing many large particles.The domain-averaged values of the 24-h surface precipitation accumulation from the two schemes were quite close to each other.However,differences existed in the temporal and spatial evolutions of the precipitation distribution.An analysis of the surface precipitation temporal evolution indicated faster precipitation in Morrison,while P3 indicated slower rainfall by shifting the precipitation pattern eastward toward what was observed.The differences in precipitation values between the two schemes were related to the cloud water content distribution and fall speeds of rimed particles.P3 simulated the stratiform precipitation event better as it captured the gradual transition in the mass-weighted fall speeds and densities from unrimed to rimed particles.  相似文献   

14.
Landfall tropical cyclones are a major kind of severe weather affecting China. The typhoon Sepat, declassified as tropical storm after its landfalling, caused a continuous heavy rainfall event over China mainland from 19th to 25th August, 2007. The storm cyclone resided over the Hunan province for 60 hours, causing observed accumulated precipitation larger than 300 mm in a large area of the Hunan province and leading severe flood events. This event was simulated using the Weather Research and Forecasting (WRF) model coupled with the surface layer scheme UTOPIA. The model was able to reproduce the main characteristics of the event, including the typhoon track and the rainfall field and timing. In addition, three sets of sensitivity experiments have been performed. In the first one, the effects of different land surface schemes (RUC, NOAH and UTOPIA) coupled with WRF on the precipitation, sensible and latent heat flux fields associated with the Typhoon Sepat (2007) were investigated. The second set of sensitivity experiments analyzed the role of the surface fluxes (sensible and latent heat flux) on the typhoon evolution. The third set of sensitivity experiments regarded the initialization of the soil moisture content. These experiments showed that both latent and sensible heat fluxes sustained this landfalling typhoon, maintaining the spiral structure of rain belt. Among the two fluxes, the latent heat one played a major role in determining the intensity, the track and the rainfall distribution of the typhoon. In addition, the correct initialization of the soil moisture content has reveled a fundamental parameter to be initialized in order to correctly evaluate the distribution and intensity of the rain field. The intercomparison between the three different land surface schemes coupled with WRF showed that the WRF-UTOPIA and WRF-NOAH outputs seem comparable between each other and physically most realistic than those of WRF-RUC. These analyses were helpful to understand the evolution and the development of the landfalling typhoon, and demonstrated that WRF-UTOPIA and WRF-NOAH could be considered a good tool for managing the risk evaluation connected with the occurrence of such events at regional scale.  相似文献   

15.
Summary Within the joint research project IMPETUS (An integrated approach to the efficient management of scarce water resources in West Africa), the effect of interactions between the Earth’s surface and the atmosphere on fresh water availability is investigated. Explorations are conducted for a river catchment in Benin by means of simulations with a non-hydrostatic mesoscale meteorological model. A combination of idealised ensemble simulations with a column version of the model and 3-D modelling of real precipitation events is employed to assess the sensitivity of precipitation to variations in the land surface. Simplified ensemble studies exhibit a dominant influence of initial soil water content and an enhanced dependence of precipitation on vegetation when soil water availability is reduced. For wet soils, the influence of parameters that determine the intensity of near-surface turbulence is dominant. 3-D modelling confirms that these relationships are useful to identify critical land use changes in realistic settings, but do not comprehensively account for the effect of heterogeneous land surface changes on regional precipitation. Instead, the interplay between surface properties, atmospheric dynamics and precipitation systems can generate intrinsic precipitation anomaly patterns that are incongruent with the imposed surface anomalies. Hence, assessments of land use change effects on precipitation for a specific region should be based on an integrated consideration of the interactions between surface processes, atmospheric forcing and precipitation systems. Based on these findings, possible effects of successive land degradation are investigated by sensitivity studies of land surface and rainfall system interaction for the Haute Vallée de l’Ouémé (HVO). In a first series of 3-D model simulations, a successive increase of the surface fraction with adverse conditions for the development of precipitation systems is performed. Within the scope of a second series a successive reduction of surface vegetation and soil water at randomly distributed areas that cover half of the simulation domain is carried out. Basically, a uniform decrease of average precipitation forced by changing conditions and a strong reduction of rainfall in some parts of the HVO are found. As a whole, the results strongly support the hypothesis of a growing risk of rainfall decrease as a result of land use changes. Current affiliation: Gesellschaft für Anlagen- und Reaktorsicherheit, Cologne, Germany.  相似文献   

16.
A surface runoff parameterization scheme that dynamically represents both Horton and Dunne runoff generation mechanisms within a model grid cell together with a consideration of the subgrid-scaie soil heterogeneity, is implemented into the National Climate Center regional climate model (RegCM_NCC). The effects of the modified surface runoff scheme on RegCMANCC performance are tested with an abnormal heavy rainfall process which occurred in summer 1998. Simulated results show that the model with the original surface runoff scheme (noted as CTL) basically captures the spatial pattern of precipitation, circulation and land surface variables, but generally overestimates rainfall compared to observations. The model with the new surface runoff scheme (noted as NRM) reasonably reproduces the distribution pattern of various variables and effectively diminishes the excessive precipitation in the CTL. The processes involved in the improvement of NRM-simulated rainfall may be as follows: with the new surface runoff scheme, simulated surface runoff is larger, soil moisture and evaporation (latent heat flux) are decreased, the available water into the atmosphere is decreased; correspondingly, the atmosphere is drier and rainfall is decreased through various processes. Therefore, the implementation of the new runoff scheme into the RegCMANCC has a significant effect on results at not only the land surface, but also the overlying atmosphere.  相似文献   

17.
利用AREM中尺度数值模式,对2005年7月8日四川盆地大暴雨天气过程进行了数值模拟,比较分析了AREM模式提供的不同降水方案、地表通量方案、地表辐射参数化方案对此次降水过程的模拟,以及对该过程中西南低涡活动特征的模拟。试验结果表明:各方案较好地反映了四川盆地西南部强降水,对其东北部的强降水模拟存在较大偏差;各方案模拟的涡度场和流场分布决定了降水区域分布;采用降水的显式云微物理过程和大尺度饱和凝结过程模拟的降水强度、低涡强度和低空急流有一定差异,后者模拟的偏强,与实况更接近;不同地表通量过程和地表辐射过程对降水、低涡和低空急流的模拟无明显差异。  相似文献   

18.
利用常规观测资料和6 h一次的NCEP 1°×1°再分析场资料对新疆2015年2月12—14日北疆暴雪过程和2015年5月17—21日南疆暴雨过程的环流形势和主要影响系统进行分析,并基于HYSPLIT模式模拟的后向轨迹分析强降水的水汽来源和输送特征。结果表明:1)2次强降水过程均发生在高空低槽东移,低层有低涡,地面有锋面气旋,高空有辐散的天气背景下。2)冬季暴雪过程中,北疆水汽主要源自西亚和中亚地区。其中源自西亚地区的干气块下沉到近地面时从下垫面获得水汽,对强降雪的贡献最大;其次是起源于中亚西南部地区近地层的湿气块对强降雪的贡献。3)春季暴雨过程中,南疆的水汽主要来自中亚的哈萨克斯坦。其中来自哈萨克斯坦南部上空的干空气下沉到近地层时从下垫面获得水汽,对强降雨的贡献最大;其次是源自哈萨克斯坦东部和东南部对流层低层的湿气块对强降雨的贡献大。4)2次强降水过程中水汽主要来自陆地而不是海洋,气块在近地层移动或下沉到近地层时,下垫面水汽蒸发使气块变湿,是强降水的水汽主要贡献者;表明春季和冬季的水汽输送通道与夏季来自阿拉伯海等低纬的水汽通道不同。  相似文献   

19.
Two land surface schemes, SCAM and CSIRO9, were used to model the measured energy fluxes during the OASIS (Observations At Several Interacting Scales) field program. The measurements were taken at six sites along a 100 km rainfall gradient. Two types of simulations were conducted: (1) offline simulations forced with measured atmospheric input data at each of the six sites, and (2) regional simulations with the two land surface schemes coupled to the regional climate model DARLAM.The two land surface schemes employ two different canopy modelling concepts: in SCAM the vegetation is conceptually above the ground surface, while CSIRO9 employs the more commonly used `horizontally tiled' approach in which the vegetation cover is modelled by conceptually placing it beside bare ground. Both schemes utilize the same below-ground components (soil hydrological and thermal models) to reduce the comparison to canopy processes only. However, the ground heat flux, soil evaporation and evapotranspiration are parameterised by the two canopy treatments somewhat differently.Both canopy concepts reproduce the measured energy fluxes. SCAM has a slightly higher root-mean standard error in the model-measurement comparison for the ground heat flux. The mean surface radiative temperature simulated by SCAM is approximately 1K lower than in the CSIRO9 simulations. However, the soil and vegetation temperatures (which contribute to the radiative temperature) varied more in the CSIRO9 simulations. These larger variations are due to the absence of a representation of the aerodynamic interactions between vegetation and ground.  相似文献   

20.
WRF耦合4个陆面过程对“6.19”暴雨过程的模拟研究   总被引:2,自引:1,他引:1  
利用WRF模式与4个陆面过程的耦合,对2010年6月19—20日的暴雨过程进行了数值模拟,并分析陆面过程对暴雨强度和范围的敏感性。结果显示:WRF耦合4个陆面过程模拟的雨带和实况分布一致,均为东西向的雨带形状,且均预报出与实况资料相似的强降水中心。在无陆面方案情况下,强降水中心的位置、范围、强度等都发生明显变化。另外地表径流预报量和降水趋势表现一致,由于土壤含水量趋于饱和,多余的降水分配给地表径流,这种剧增的地表径流也是洪水暴涨、水位上升的重要原因。在较湿的土壤状况下,由于净辐射增长,有利于产生厚度更小的边界层高度以及更大的地表向上潜热通量,这也是导致本次降水过程异常增幅的一个重要原因。  相似文献   

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