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对SAS积云参数化方案中的云底质量通量进行限制并将其应用到华南区域高分辨率模式降水预报中,分别对强对流个例和弱对流个例进行模拟和比较,分析了限制云底质量通量之后的积云参数化方案对模式降水预报的影响,并探讨了不同大小的云底质量通量限制对预报结果的敏感性。试验结果表明,对积云参数化方案进行闭合时采用不稳定能量释放假设要比原来的准平衡闭合假设更适用于中小尺度模式。对积云参数化方案的云底质量通量进行限制以后可以有效地消除对流参数化在高分辨率模式中引起的虚假降水,同时又能够合理地引入一些次网格尺度的弱对流的影响,从而改进模式的降水预报效果。敏感性试验结果表明,随着云底质量通量限制程度的变弱,对流参数化方案对模式降水预报的影响会逐渐增强;在一定大小范围内的云底质量通量限制下,强对流个例的总降水量预报结果对于不同大小的限制不如弱对流个例敏感。对两种不同的云底质量通量限制方式进行比较发现,在云底质量通量较大时完全关闭对流参数化方案可以更有效避免对流参数化引起的虚假降水。 相似文献
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修正的质量通量积云对流方案及其模拟试验研究 Ⅱ:三种积云方案的积云对流活动及MFS方案相关参数的敏感性试验 总被引：4，自引：1，他引：4
作者在“修正的质量通量积云对流方案及其模拟试验研究I方案介绍及对1991年洪涝过程的模拟”论文中提出的质量通量方案成功地植入区域气候模式RegCM2的基础上，对比分析质量通量方案MFS，Kuo方案和Grell方案对积云对流活动的模拟，结果表明质量通量方案较好地模拟了积云对流活动过程。针对质量通量方案中的一些参数，如云水向雨水的转换率、混合卷入率、混合卷出率和下沉气流的强度等进行了一系列的敏感性试验，试验结果表明积云对流活动对这些参数比较敏感，因此提高这些参数的准确性是改进积云对流参数化方案的重要内容之一。 相似文献
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一种改进的质量通量积云参数化方案及预报试验 总被引：2，自引：1，他引：1
用国家气象中心有限区域业务预报模式,以１９９８年８月一次热带风暴降水过程为试验个例,对引入了下曳气流的质量通量积云对流参数方案和模式中的原质量通量积云参数化方案进行了对比试验。结果显示;引入了下曳气流后,通过提高对流降水量使降雨强度预报得以提高,更接近于实况;改进后的方案对大雨以上预报水平有一定的改善,各项评分结果均有所提高。 相似文献
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低纬高原上中尺度模式的积云参数化方案研究 总被引：4，自引：5，他引：4
在低纬高度上的中尺度数值模式研究中，积云参数化方案的设计是极其重要的，而垂直加热廓线和增湿系数的方案设计是Kuo型积云参数化方案中两个重要的问题。本文从垂直加热廓线和增湿系数的角度设计了多种改进的Kuo型积云参数化方案进行数值试验。试验结果表明，垂直加热廓线采用位湿法，增湿系数采用指数型定义法的Kuo型改进方案较适合云南低纬高原上的中尺度数值模式；低纬高原上的增湿系数比我国东部沿海及一些平原地区要大；在改进积云参数化方案的基础上考虑低纬高原地形的影响，能进一步提高中尺度数值模式在低纬高原上的模拟效果。 相似文献
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MM5模式中积云参数化方案在西南地区适应性的进一步试验分析 总被引：1，自引：0，他引：1
何光碧 《高原山地气象研究》2009,29(3):12-19
针对四川盆地4次暴雨过程,利用MM5中尺度数值模式,进行了Grell和Kuo对流参数化方案及两重区域采用不同方案组合的数值试验,分析了不同试验对降水的模拟能力。结果表明,不同试验方案在降水落区、强度、演变及降水性质分配上存在一定程度的差异。细网格区域降水强度及落区主要由本区域所采用的积云参数化方案所决定。模式采用Kuo方案预报的雨区少动,主要降水落区偏西、偏南,降水强度偏弱,采用Grell方案与粗网格采用Kuo方案而细网格采用Grell方案预报结果接近,能够较好地预报雨区东移,降水强度预报更接近实况。Kuo方案以对流降水为主,Grell方案模拟的以非对流降水与对流降水两种性质降水各占一定比例,有小幅度变化,可能更能反映实际降水性质。过程分析结合统计检验表明,两重区域均采用Grell方案预报效果相对较好。同时也看到,没有哪种对流参数化方案是完备的。发展具有区域特色的对流参数方案有着重要和实际意义。 相似文献
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不同积云对流参数化方案对中国东部降水模拟的对比分析 总被引：4，自引：4，他引：0
本文将目前国际上气候模式中应用比较广泛的三种积云对流参数化方案引入到P-σRCM9区域气候模式中,并考察了不同积云对流参数化方案对P-σRCM9区域气候模式模拟中国降水性能的影响.分析发现四种积云对流参数化方案(包括原方案)下模拟的积云对流加热率基本上都呈现出单峰特征,且加热峰值出现在对流层中低层.并发现积云对流参数化方案对冬季降水平均场和年际变率模拟的影响较小,而对夏季降水模拟的影响更加重要.同时注意到Kuo方案和Anthes-Kuo方案模拟的冬、夏季降水平均场和年际变率均较其他两个方案更接近观测. 相似文献
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修正的ECMWF质量通量积去参数化方案的预报试验 总被引：1，自引：4，他引：1
用一个有限区域业务预报模式，以１９９５年７－８月西北地区几次大范围的降水天气过程为试验个例，对经过修改的ＥＣＭＷＦ质量通量积云参数化方案和模式中的原Ｋｕｏ型积云型数化方程进行了１３例４８ｈ的批量对比预报试验。 相似文献
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数值预报的误差来源于初始场和模式的误差,集合预报技术是减小这些误差的有效方法。该文以MM5模式作为试验模式框架,模式的积云参数化方案分别取Anthes-Kuo、Grell、Kain-Fritsch和Betts-Miller方案,边界层参数化方案分别取MRF和Eta方案,通过组合4种积云参数化方案和两种边界层参数化方案产生8个集合成员,对1999年华东地区梅雨期间3个降水个例进行48 h集合预报试验。结果显示不同集合成员的预报结果各不相同,积云参数化方案对降水的影响比边界层参数化方案对降水的影响大;不同集合成员预报降水的偏差也各不相同,大多存在湿偏差,量级小的降水的湿偏差程度比量级大的降水的湿偏差程度小;对于不同个例,各成员中预报效果相对较好的成员是不同的,集合平均后可以得到一个比较稳定的预报结果;从集合预报结果中还能得到客观化和定量化的降水概率预报,它能对可能发生的天气现象发出信号。 相似文献
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WRF模式对青藏高原南坡夏季降水的模拟分析 总被引：2，自引：0，他引：2
利用中尺度数值模式WRF研究积云对流参数化方案、网格嵌套技术和模式分辨率对陡峭的青藏高原南坡夏季降水模拟的影响。对2006年7月青藏高原南坡地区降水的模拟分析表明:降水对积云对流参数化方案的选择很敏感,不同方案模拟的结果差异显著,采用Grell-Devenyi质量通量方案时的模拟效果优于其他方案。在此基础上,通过5种试验方案比较发现,使用积云对流参数化方案、提高模式分辨率和应用网格嵌套技术能改善降水强度和空间分布的模拟,组合使用时模拟的降水与观测资料更接近。它们均能改进风场,使得水汽的输送和辐合过程的模拟更加准确;还能影响大气的垂直加热状态,导致不同的对流发生,使垂直速度的分布趋于合理。未使用积云对流参数化方案时,大气湿度偏小,而模式分辨率和网格嵌套技术对大气湿度的影响不大。 相似文献
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An improvement of the mass flux convection parameterization scheme and its sensitivity tests for seasonal prediction over China 总被引：1，自引：1，他引：0
A modified cumulus parameterization scheme, suitable for use in a seasonal forecast model, is presented. This parameterization scheme is an improvement of the mass flux convection scheme developed by Gregory and Rowntree (1989; 1990). This convection scheme uses a “bulk” cloud model to present an ensemble of convective clouds, and aims to represent shallow, deep, and mid-level convection. At present,this convection scheme is employed in the NCC T63L20 model (National Climate Center, China Meteorological Administration). Simulation results with this scheme have revealed some deficiencies in the scheme,although to some extent, it improves the accuracy of the simulation. In order to alleviate the deficiencies and reflect the effect of cumulus convection in the actual atmosphere, the scheme is modified and improved.The improvements include (i) the full estimation of the effects of the large-scale convergence in the lower layer upon cumulus convection, (ii) the revision of the initial convective mass flux, and (iii) the regulation of convective-scale downdrafts. A comparison of the results obtained by using the original model and the modified one shows that the improvement and modification of the original convection scheme is successful in simulating the precipitation and general circulation field, because the modified scheme provides a good simulation of the main features of seasonal precipitation in China, and an analysis of the anomaly correlation eoetfieient between the simulation and the observations confirms the improved results. 相似文献
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Summary The Regional Climate Model RegCM3 has been used to examine its suitability in simulating the Indian summer monsoon circulation
features and associated rainfall. The model is integrated at 55 km horizontal resolution over a South Asia domain for the
period April–September of the years 1993 to 1996. The characteristics of wind at 850 hPa and 200 hPa, temperature at 500 hPa,
surface pressure and rainfall simulated by the model over the Indian region are examined for two convective schemes (a Kuo-type
and a mass flux scheme). The monsoon circulation features simulated by RegCM3 are compared with those of the NCEP/NCAR reanalysis
and the simulated rainfall is validated against observations from the Global Precipitation Climatology Centre (GPCC) and the
India Meteorological Department (IMD). Validation of the wind and temperature fields shows that the use of the Grell convection
scheme yields results close to the NCEP/NCAR reanalysis. Similarly, the Indian Summer Monsoon Rainfall (ISMR) simulated by
the model with the Grell convection scheme is close to the corresponding observed values. In order to test the model response
to land surface changes such as the Tibetan snow depth, a sensitivity study has also been conducted. For such sensitivity
experiment, NIMBUS-7 SMMR snow depth data in spring are used as initial conditions in the RegCM3. Preliminary results indicate
that RegCM3 is very much sensitive to Tibetan snow. The model simulated Indian summer monsoon circulation becomes weaker and
the associated rainfall is reduced by about 30% with the introduction of 10 cm of snow over the Tibetan region in the month
of April. 相似文献
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In this study, the improved high-resolution regional climate model of the China National Climate Center （RegCM_NCC） is used to examine the sensitivity of the simulated circulation and rainfall during the South China Sea summer monsoon （SCSSM） period during 1998 in an effort to compare to other cumulus param- eterization schemes. The investigation has indicated that the model is capable of simulating the seasonal march of the SCSSM and that the results were very sensitive to the choice of cumulus parameterization schemes. It seems that the Kuo cumulus parameterization scheme simulates the process of the SCSSM onset reasonably well, which can reproduce the onset timing and dramatic changes before and after the onset, especially the upper- and lower-level wind-fields. However, there are still some discrepancies between the simulations and observations. For example, the model can not completely simulate the intensity of the rainfall or the location of the western Pacific subtropical high as well as the feature of the rapid northward propagation of seasonal rain belt. 相似文献
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CAM3模式海气湍流通量参数化的改进及其应用 总被引：1，自引：0，他引：1
通过对流性阵风参数化方法,在CAM3原有海气湍流通量参数化方案(CAM3方案)中引入边界层自由对流和降水深对流对海表湍流通量的贡献,改进了CAM3模式的海气湍流通量参数化方案(CAM3 ME方案).在此基础上,利用观测海温积分改进的CAM3模式,分析改进模式对冬(DJF)、夏季(JJA)大气环流异常的模拟性能.结果表明,采用改进的海气湍流通量参数化方案,模式对冬(DJF)、夏季(JJA)大气环流异常年际变化的模拟能力有了很大提高,尤其是冬季(DJF)北太平洋和北美大陆地区以及夏季(JJA)南半球海洋上空. 相似文献
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In this study, the improved high-resolution regional climate model of the China National Climate Center (RegCM_NCC) is used to examine the sensitivity of the simulated circulation and rainfall during the South China Sea summer monsoon (SCSSM) period during 1998 in an effort to compare to other cumulus parameterization schemes. The investigation has indicated that the model is capable of simulating the seasonal march of the SCSSM and that the results were very sensitive to the choice of cumulus parameterization schemes. It seems that the Kuo cumulus parameterization scheme simulates the process of the SCSSM onset reasonably well, which can reproduce the onset timing and dramatic changes before and after the onset, especially the upper- and lower-level wind-fields. However, there are still some discrepancies between the simulations and observations. For example, the model can not completely simulate the intensity of the rainfall or the location of the western Pacific subtropical high as well as the feature of the rapid northward propagation of seasonal rain belt. 相似文献
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《Atmospheric Research》2010,95(4):743-753
Convection can cause severe precipitation events and is thus of major interest for quantitative precipitation forecasts. Due to its small horizontal scale convection usually has to be parameterized in numerical weather prediction (NWP) models as a subgrid scale phenomenon. Classical mass flux convection schemes assume grid box sizes much larger than the scale of the convective circulation. Thus, the convective mass transport is closed in the local grid column and no net mass transport occurs on the grid scale.In contemporary NWP models with grid sizes of a few kilometers, where convection is already partially resolved, the classical approach leads to a conceptual problem. This can be overcome by a hybrid mass flux convection scheme (HYMACS), in which only the small scale convective updrafts and downdrafts are parameterized, whereas the treatment of the larger scale environmental subsidence is left to the grid scale equations. Different to the classical schemes, HYMACS produces a net convective mass flux exerting pressure gradient forces to the grid scale model.We discuss real cases of different meteorological situations simulated with the operational weather forecast model COSMO of the German Meteorological Service as the hosting model of HYMACS. Precipitation and cloud top pressures simulated with HYMACS are compared with results from classical convection schemes and observational data from the DWD station network and the SEVIRI (MSG) satellite instrument. 相似文献
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利用高分辨率的区域气候模式 (RegCM_NCC) 对南海夏季风爆发进行模拟研究。研究表明:该模式对积云对流参数化方案的选择十分敏感, 其中以Kuo积云参数化方案为最好, 可以比较成功地模拟出南海夏季风的爆发时间、爆发前后高、低层风场的剧烈变化以及季风与季风雨带的向北推进。然而该方案对于雨量和副热带高压位置的模拟, 与观测相比尚存在一定的偏差, 主要表现为副热带高压位置模拟偏北、偏东; 南海地区的降水量模拟偏少、降水范围偏小。此外, 采用4种参数化方案 (Kuo, Grell, MFS, Betts-Miller) 集成的结果在某种程度上要优于单个方案的结果, 这种改善主要体现在对南海地区季风爆发后降水的模拟上。 相似文献
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Deepesh Kumar Jain Arindam Chakraborty Ravi S. Nanjundiah 《Meteorology and Atmospheric Physics》2013,122(3-4):159-173
The simulation of precipitation in a general circulation model relying on relaxed mass flux cumulus parameterization scheme is sensitive to cloud adjustment time scale (CATS). In this study, the frequency of the dominant intra-seasonal mode and interannual variability of Indian summer monsoon rainfall (ISMR) simulated by an atmospheric general circulation model is shown to be sensitive to the CATS. It has been shown that a longer CATS of about 5 h simulates the spatial distribution of the ISMR better. El Niño Southern Oscillation–ISMR relationship is also sensitive to CATS. The equatorial Indian Ocean rainfall and ISMR coupling is sensitive to CATS. Our study suggests that a careful choice of CATS is necessary for adequate simulation of spatial pattern as well as interannual variation of Indian summer monsoon precipitation. 相似文献
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本文介绍一个简单、经济的适用于各种多层大气环流模式中计算臭氧加热率的参数化方案,利用这一方案,可根据臭氧总量气候观测值及其垂直分布资料计算臭氧加热率,也可以在模式中加入臭氧方程,用预报的臭氧含量计算臭氧加热率.用此方案对单站气候资料试算,结果指出,随着高度的增加,臭氧吸收太阳辐射对大气太阳加热率的贡献逐渐接近、达到并在平流层50hPa附近明显超过其它物质如水汽的贡献.此方案用于九层大气环流模式时,对其辐射加热率的计算有较理想的改进,并使模拟的大气温度垂直分布更符合观测事实. 相似文献