中国地区对流参数化加热廓线的分析研究和数值试验          下载免费PDF全文

朱蓉  徐大海 《应用气象学报》1996,7(2):221-228

为了使MM4模式在我国范围内得到很好的应用，需用我国的气候资料对MM4模式中的对流加热参数进行统计分析，以适应我国各地区气候状态。为此，本文选取了1990～1993年6～8月的常规探空资料，采用郭氏的对流参数化方案，放宽假设后直接计算求得各站点各时次的对流加热率参数，再按气象站的站区分区进行统计。结果表明:黄河以南地区，对流云上、下部的垂直加热率比较均匀，加热廓线峰值偏低，为σ=0.65～0.80，对流云顶也比较高。黄河以北地区，对流云中的垂直加热率分布不均，加热集中在某一层上，加热廓线峰值出现在σ=0.  相似文献   

植被冠层湍流代数应力模式     

张运福  储长树 《气象》1996,22(5):39-42

从植被冠层湍流时空平均雷诺应力方程出发，根据植被冠层内有关参数化的准则，建立了湍流代数应力模式，并用玉米和小麦两种作物地的实测资料对模式进行了验证。  相似文献   

EFFECTS OF SPATIAL VARIABILITY ON THE SCALING OF LAND SURFACE PARAMETERIZATIONS   总被引：1，自引：0，他引：1  

ZHENGLIN HU  SHAFIQUL ISLAM 《Boundary-Layer Meteorology》1997,83(3):441-461

Understanding and modelling physical and dynamical processes over heterogeneous land surfaces have becomea central focus of many recent studies. There is aconsiderable debate, however, over how to representthe effects of spatial heterogeneity in mesoscale andglobal scale models. Here, a computationally efficientanalytical approach is presented to evaluate scalingproperties of land surface representations. It isshown that the effects of spatial variability may not benegligible for commonly encountered land surfaces andassociated parameterizations. Second-order correction termsinvolving variances of the parameters and covariancesof each pair of land surface parameters are developedto account for the effects ofheterogeneity. Using this analytical approach, weshow that the detail of spatial heterogeneity may not beimportant for the infrared radiation and reflectedsolar radiation from the surface, while sensible andlatent heat fluxes are shown to be sensitive toheterogeneity. Assumptions related todifferent parameterizations for the same physicalprocess could potentially lead to different inferencesregarding the influence of spatial heterogeneity. Theproposed approach, however, is capable of identifying therole of different parameterizations in estimating theinfluence of spatial heterogeneity. These analyticalresults are consistent with the results of severalrecent numerical and field experiments that deal withthe effects of small-scale heterogeneity in landsurface characteristics.  相似文献   

Nonlinear interactions between gravity waves and tides   总被引：1，自引：0，他引：1  

Liu Xiao  Xu JiYao  Ma RuiPing 《中国科学D辑(英文版)》2007,50(8):1273-1279

In this study, we present the nonlinear interactions between gravity waves (GWs) and tides by using the 2D numerical model for the nonlinear propagation of GWs in the compressible atmosphere. During the propagation in the tidal background, GWs become instable in three regions, that is z = 75―85 km, z = 90―110 km and z = 115―130 km. The vertical wavelength firstly varies gradually from the initial 12 km to 27 km. Then the newly generated longer waves are gradually compressed. The longer and shorter waves occur in the regions where GWs propagate in the reverse and the same direction of the hori-zontal mean wind respectively. In addition, GWs can propagate above the main breaking region (90—110 km). During GWs propagation, not only the mean wind is accelerated, but also the amplitude of tide is amplified. Especially, after GWs become instable, this amplified effect to the tidal amplitude is much obvious.  相似文献   

热带大气季节内振荡数值模拟对积云对流参数化方案的敏感性   总被引：4，自引：0，他引：4  

贾小龙  李崇银 《气象学报》2007,65(6):837-855

利用中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室(LASG)的大气环流模式(SAMIL-R42L9)研究了热带大气季节内振荡(MJO)的模拟对积云对流参数化方案的敏感性,结果表明两种对流参数化方案——湿对流调整方案(MCA)和Zhang-McFarlane(1995年)方案对MJO的模拟能力有明显的差异。MCA方案较好地模拟出了MJO的基本特征,包括季节内的时间尺度和向东的传播。Zhang-McFarlane(1995年)对流方案模拟的MJO振幅非常弱,而且缺乏连续的传播特征,在MJO的演变过程中弱的低层水汽辐合使MJO难以维持和传播。两种不同的对流参数化方案产生的非绝热加热垂直廓线明显不同,Zhang-McFarlane(1995年)方案产生的非绝热加热强度在对流层各层过于一致,没有明显的最大加热层,而且平均的加热强度太弱,这是该方案难以模拟出合理的MJO的主要原因之一。因此,模式对热带大气季节内振荡的模拟能力很大程度上依赖于所使用的积云对流参数化方案,当积云参数化方案改变时模式模拟的MJO也发生明显变化,而非绝热加热廓线是对流参数化方案影响MJO模拟的一个重要影响因子。3种不同的非绝热加热垂直分布的敏感性试验表明,当最大的加热层位于对流层中低层尤其是对流层中层时,更容易产生出与观测较为接近的季节内的扰动,而当最大加热位于对流层高层时,更易于激发出西传的扰动。  相似文献   

Sensitivity Study of the South China Sea Summer Monsoon in 1998 to Different Cumulus Parameterization Schemes     

柳艳菊  丁一汇 《大气科学进展》2007,24(3):360-376

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   

Microphysical and radiative properties of mixed-phase altocumulus: A model evaluation of glaciation effects     

Kenneth Sassen  Vitaly I. Khvorostyanov   《Atmospheric Research》2007,84(4):390-398

Using a cloud model with explicit microphysics and radiation, we evaluate the microphysical changes in a supercooled liquid altocumulus cloud with increasing ice content, until glaciation occurs. The properties of the ice and water particle constituents are resolved independently, revealing the relative radiative contributions from the water phase source cloud versus the ice phase virga. Cloud contents are also converted to millimeter-wave radar reflectivities to shed light on the ability of such radars to study these ubiquitous clouds. The results show that the radiative and radar backscattering properties of mixed-phase clouds are dominated by the cloud droplets and ice crystals they contain, respectively.  相似文献   

中尺度模式中各种积云参数化方案的对比试验   总被引：10，自引：2，他引：10  

晏红明  任菊章  段玮 《南京气象学院学报》2006,29(4):491-499

利用非静力中尺度MM5数值模式，选择Anthes-Kuo、Grell、Kain-Fritsch和Betts-Miller4种积云对流参数化方案，对2003年7月25-26日台风登陆减弱为中尺度低压系统后影响云南产生的强降水过程进行模拟试验，重点分析了4种参数化方案模拟的降水分布、降水强度和中尺度低压的流场特征。结果表明：4种积云参数化方案对这次强降水过程均有一定的模拟能力，能够很好地模拟过程强降水中心的位置，但Grell、Kain-Fritsch和Betts-Miller3种方案模拟的大雨范围比实况大雨范围明显偏小，Betts-Miller方案模拟的降水强度比实况偏大，Anthes-Kuo方案的模拟结果与实况比较接近，它不仅能够很好地模拟强降水过程的降水区范围、降水强度和降水中心位置，还能很好地再现低压环流系统的一些中尺度特征。  相似文献   

冻土模式的改进和发展   总被引：7，自引：0，他引：7  

李倩  孙菽芬 《地球科学进展》2006,21(12):1339-1349

本研究首先对当今常用的冻土模式进行了改进。以土壤总焓和土壤水总质量替代原来的温度和体积水含量作为方程预报量，使冰水相变速率项变为诊断量，避免了原冻土模式计算过程中由于冰水相变速率项预估的误差造成计算过程中的温度偏差。同时对该新形式模式所发展的诊断量方程组设计了合理省时的数值计算方案。实验表明，改进后模式的模拟结果与观测值有较好的吻合。此外，分析比较了目前常用的3种冻融方案的理论基础及模拟结果，发现基于热力学平衡态推导得到的包含土壤水势影响的参数化方案能很好地模拟土壤的冻融变化过程，不同的冻融方案会对土壤内的温度、水量及表面的感热和潜热模拟结果产生较大的影响。   相似文献   

北京地区夏季边界层结构日变化的高分辨模拟对比   总被引：14，自引：4，他引：14       下载免费PDF全文

陈炯  王建捷 《应用气象学报》2006,17(4):403-411

使用WRF中尺度数值模式, 分别选用两种不同的边界层参数化方案 (MYJ, YSU) 和3种陆面参数化方案 (SLAB, Noah, RUC), 对2004年7月1日08:00—7月4日20:00 (北京时) 北京地区夏季边界层结构进行1 km的高分辨模拟。对比分析了近地面层风场、温度场以及边界层的日变化特征, 结果发现:WRF模式基本模拟出了北京夏季边界层的日变化特征; 在边界层方案中, MYJ方案描述的边界层结构较YSU方案合理; Noah陆面模式较好地反映了城市的热岛效应; 无降水时, 风速及边界层高度对于陆面过程不敏感, 而降水发生后, 陆面过程对于边界层结构的影响增大; 各方案模拟的城区风速明显偏大, 这是因为没有充分考虑城市建筑物的阻力作用。  相似文献