共查询到18条相似文献，搜索用时 109 毫秒
1.
A nested regional climate model has been experimentally used in the seasonal prediction at the China National Climate Center (NCC) since 2001. The NCC/IAP (Institute of Atmospheric Physics) T63 coupled GCM (CGCM) provides the boundary and initial conditions for driving the regional climate model (RegCM NCC). The latter has a 60-km horizontal resolution and improved physical parameterization schemes including the mass flux cumulus parameterization scheme, the turbulent kinetic energy closure scheme (TKE) and an improved land process model (LPM). The large-scale terrain features such as the Tibetan Plateau are included in the larger domain to produce the topographic forcing on the rain-producing systems. A sensitivity study of the East Asian climate with regard to the above physical processes has been presented in the first part of the present paper. This is the second part, as a continuation of Part I. In order to verify the performance of the nested regional climate model, a ten-year simulation driven by NCEP reanalysis datasets has been made to explore the performance of the East Asian climate simulation and to identify the model’s systematic errors. At the same time, comparative simulation experiments for 5 years between the RegCM2 and RegCM NCC have been done to further understand their differences in simulation performance. Also, a ten-year hindcast (1991–2000) for summer (June–August), the rainy season in China, has been undertaken. The preliminary results have shown that the RegCM NCC is capable of predicting the major seasonal rain belts. The best predicted regions with high anomaly correlation coefficient (ACC) are located in the eastern part of West China, in Northeast China and in North China, where the CGCM has maximum prediction skill as well. This fact may reflect the importance of the largescale forcing. One significant improvement of the prediction derived from RegCM NCC is the increase of ACC in the Yangtze River valley where the CGCM has a very low, even a negative, ACC. The reason behind this improvement is likely to be related to the more realistic representation of the large-scale terrain features of the Tibetan Plateau. Presumably, many rain-producing systems may be generated over or near the Tibetan Plateau and may then move eastward along the Yangtze River basin steered by upper-level westerly airflow, thus leading to enhancement of rainfalls in the mid and lower basins of the Yangtze River. The real-time experimental predictions for summer in 2001, 2002, 2003 and 2004 by using this nested RegCM NCC were made. The results are basically reasonable compared with the observations. 相似文献
2.
Based on the existing cumulus convective parameterization schemes,a mass flux scheme(MFS)for cumulus convective parameterization has been successfully developed by reference to thework of Chen et al.(1996).The MFS is a comprehensive scheme.In MFS,not only theimportance of the large-scale moisture convergence is taken into account,but also it includes thecumulus updrafts and downdrafts,cumulus-induced subsidence in the environmental air.entrainment,detrainment and evaporation.The interaction between the cumulus and theenvironment is described by using a one-dimensional bulk model.At the same time the schemeincludes the penetrative and shallow convections.The MFS has been successfully incorporated into the regional climate model RegCM2developed by NCAR.The new model has been applied to simulate summer monsoon characteristicsand their variations of heavy rainfall process in the Changjiang-Huaihe River Basins for threemonths from May to July 1991.The results show that the new model can successfully simulate thisrainfall prolonged process.By comparising the model outputs of RegCM2.using the Kuo schemeand the MFS.it is found that the MFS is better in simulating the surface temperature,rainfallposition and amount,and rainfall duration. 相似文献
3.
Convective processes affect large-scale environments through cloud-radiation interaction, cloud micro- physical processes, and surface rainfall processes. Over the last three decades, cloud-resolving models （CRMs） have demonstrated to be capable of simulating convective-radiative responses to an imposed large-scale forcing. The CRM-produced cloud and radiative properties have been utilized to study the convective- related processes and their ensemble effects on large-scale circulations. This review the recent progress on the understanding of convective processes with the use of CRM simulations, including precipitation processes; cloud microphysical and radiative processes; dynamical processes; precipitation efficiency; diurnal variations of tropical oceanic convection; local-scale atmosphere-ocean coupling processes; and tropical convective-radiative equilibrium states. Two different ongoing applications of CRMs to general circulation models （GCMs） are discussed： replacing convection and cloud schemes for studying the interaction between cloud systems and large-scale circulation, and improving the schemes for climate simulations. 相似文献
4.
A model for studying the heat and mass exchange between the atmosphere and a water body is developed, in which the phase change process of water freezing in winter and melting in summer and the function of the convective mixing process are taken into consideration. The model uses enthalpy rather than temperature as the predictive variable. It helps to set up governing equations more concisely, to deal with the phase change process more easily, and make the numerical scheme simpler. The model is verified by observed data from Lake Kinneret for a non-frozen lake in summer time, and Lake Lower Two Medicine for a frozen lake in winter time. Reasonably good agreements between the model simulations and observed data indicate that the model can serve as a component for a water body in a land surface model. In order to more efficiently apply the scheme in a climate system model, a sensitivity study of various division schemes with less layers in the vertical direction in the water body is conducted. The results of the study show that the division with around 10 vertical layers could produce a prediction accuracy that is comparable to the fine division with around 40 layers. 相似文献
5.
An ensemble prediction system based on the GRAPES model, using multi-physics, is used to discuss the influence of different physical processes in numerical models on forecast of heavy rainfall in South China in the annually first raining season(AFRS). Pattern, magnitude and area of precipitation, evolution of synoptic situation, as well as apparent heat source and apparent moisture sink between different ensemble members are comparatively analyzed. The choice of parameterization scheme for land-surface processes gives rise to the largest influence on the precipitation prediction. The influences of cumulus-convection and cloud-microphysics processes are mainly focused on heavy rainfall;the use of cumulus-convection parameterization tends to produce large-area and light rainfall. Change in parameterization schemes for land-surface and cumulus-convection processes both will cause prominent change in forecast of both dynamic and thermodynamic variables, while change in cloud-microphysics processes show primary impact on dynamic variables. Comparing simplified Arakawa-Schubert and Kain-Fritsch with Betts-Miller-Janjic schemes, SLAB with NOAH schemes, as well as both WRF single moment 6-class and NCEP 3-class with simplified explicit schemes of phase-mixed cloud and precipitation shows that the former predicts stronger low-level jets and high humidity concentration, more convective rainfall and local heavy rainfall, and have better performance in precipitation forecast. Appropriate parameterization schemes can reasonably describe the physical process related to heavy rainfall in South China in the AFRS, such as low-level convergence, latent heat release, vertical transport of heat and water vapor, thereby depicting the multi-scale interactions of low-level jet and meso-scale convective systems in heavy rainfall suitably, and improving the prediction of heavy rainfall in South China in the AFRS as a result. 相似文献
6.
Regional climate simulations in Asia from May 1997 to August 1998 were performed using the Seoul National University regional climate model （SNURCM） and Iowa State University regional climate model （ALT.MM5/LSM）, which were developed by coupling the NCAR/Land Surface Model （LSM） and the Mesoscale Model （MM5）. However, for physical processes of precipitation, the SNURCM used the Grell scheme for the convective parameterization scheme （CPS） and the simple ice scheme for the explicit moisture scheme （EMS）, while the ALT.MM5/LSM used the Betts-Miller scheme for CPS and the mixed phase scheme for EMS.
The simulated precipitation patterns and amounts over East Asia for the extreme climatic summer in 1997 （relative drought conditions） and 1998 （relative flood conditions） were especially focused upon. The ALT.MM5/LSM simulated more precipitation than was observed in 1997 due to more moisture and cloud water in the lower levels, despite weak upward motion. In the SNURCM, strong upward motion resulted in more precipitation than that was observed in 1998, with more moisture and cloud water in the middle levels. In the ALT.MM5/LSM, weak upward motion, unchanged moisture in the lower troposphere, and the decrease in latent heat flux at the surface increased convective precipitation only by 3% for the 1998 summer event. In the SNURCM, strong upward motion, the increase in moisture in the lower troposphere, and the increase in latent heat flux at the surface increased convective precipitation by 48% for the summer of 1998. The main differences between both simulations were moisture availability and horizontal momentum transport in the lower troposphere, which were also strongly influenced by large-scale forcing. 相似文献
The simulated precipitation patterns and amounts over East Asia for the extreme climatic summer in 1997 （relative drought conditions） and 1998 （relative flood conditions） were especially focused upon. The ALT.MM5/LSM simulated more precipitation than was observed in 1997 due to more moisture and cloud water in the lower levels, despite weak upward motion. In the SNURCM, strong upward motion resulted in more precipitation than that was observed in 1998, with more moisture and cloud water in the middle levels. In the ALT.MM5/LSM, weak upward motion, unchanged moisture in the lower troposphere, and the decrease in latent heat flux at the surface increased convective precipitation only by 3% for the 1998 summer event. In the SNURCM, strong upward motion, the increase in moisture in the lower troposphere, and the increase in latent heat flux at the surface increased convective precipitation by 48% for the summer of 1998. The main differences between both simulations were moisture availability and horizontal momentum transport in the lower troposphere, which were also strongly influenced by large-scale forcing. 相似文献
7.
Numerical Simulation Experiment of Land Surface Physical Processes and Local Climate Effect in Forest Underlying Surface 总被引：1，自引：0，他引：1 
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下载免费PDF全文 LIU Shuhu PAN Ying DENG Yi MA Mingmin JIANG Haimei LIN Hongtao JIANG Haoyu LIANG Fuming LIU Heping WANG Jianhua 《Acta Meteorologica Sinica》2006,20(1):72-85
Based on the basic principles of atmospheric boundary layer and plant canopy micrometeorology, a forest underlying surface land surface physical process model and a two-dimensional atmospheric boundary layer numerical model are developed and numerical simulation experiments of biosphere and physiological processes of vegetation and soil volumetric water content have been done on land surface processes with local climate effect. The numerical simulation results are in good agreement with realistic observations, which can be used to obtain reasonable simulations for diurnal variations of canopy temperature, air temperature in canopy, ground surface temperature, and temporal and spatial distributions of potential temperature and vertical wind velocity as well as relative humidity and turbulence exchange coefficient over non-homogeneous underlying surfaces. It indicates that the model developed can be used to study the interaction between land surface process and atmospheric boundary layer over various underlying surfaces and can be extended to local climate studies. This work will settle a solid foundation for coupling climate models with the biosphere. 相似文献
8.
有关雪盖模型内部及界面过程的参数化方案的敏感试验 总被引：4，自引：0，他引：4
In order to develop a seasonal snow model of land surface process as accurately as possible for climatic study, it is necessary to fully understand the effects of important snow internal processes and interaction with air and to get an insight into influence of several relevant parameterization schemes with parameters＇ uncertainty to some degree. Using the snow model (SAST) developed by first author and other one and some useful field observation data, this paper has conducted a series of sensitivity studies on the parameterization schemes. They are relative to compaction process, snow thermal conduction, methodology of layering snow pack and to key parameters such as snow albedo, water holding capacity. Then, based on the results from the sensitivity studies, some useful conclusions for snow cover model improvement are ob tained from the analysis of the results. 相似文献
9.
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
10.
Aerosol-Cloud-Precipitation Interactions in WRF Model: Sensitivity to Autoconversion Parameterization 下载免费PDF全文
下载免费PDF全文 Cloud-to-rain autoconversion process is an important player in aerosol loading, cloud morphology, and precipitation variations because it can modulate cloud microphysical characteristics depending on the participation of aerosols, and affects the spatio-temporal distribution and total amount of precipitation. By applying the Kessler, the Khairoutdinov-Kogan(KK), and the Dispersion autoconversion parameterization schemes in a set of sensitivity experiments, the indirect effects of aerosols on clouds and precipitation are investigated for a deep convective cloud system in Beijing under various aerosol concentration backgrounds from 50 to 10000 cm-3. Numerical experiments show that aerosol-induced precipitation change is strongly dependent on autoconversion parameterization schemes. For the Kessler scheme, the average cumulative precipitation is enhanced slightly with increasing aerosols, whereas surface precipitation is reduced significantly with increasing aerosols for the KK scheme. Moreover, precipitation varies non-monotonically for the Dispersion scheme, increasing with aerosols at lower concentrations and decreasing at higher concentrations.These different trends of aerosol-induced precipitation change are mainly ascribed to differences in rain water content under these three autoconversion parameterization schemes. Therefore, this study suggests that accurate parameterization of cloud microphysical processes, particularly the cloud-to-rain autoconversion process, is needed for improving the scientific understanding of aerosol-cloud-precipitation interactions. 相似文献
11.
DING Yihui SHI Xueli LIU Yiming LIU Yan LI Qingquan QIAN Yongfu MIAO Manqian ZHAI Guoqing GAO Kun 《大气科学进展》2006,23(3)
A modified version of the NCAR/RegCM2 has been developed at the National Climate Center (NCC), China Meteorological Administration, through a series of sensitivity experiments and multi-year simulations and hindcasts, with a special emphasis on the adequate choice of physical parameterization schemes suitable for the East Asian monsoon climate. This regional climate model is nested with the NCC/IAP (Institute of Atmospheric Physics) T63 coupled GCM to make an experimental seasonal prediction for China and East Asia. The four-year (2001 to 2004) prediction results are encouraging. This paper is the first part of a two-part paper, and it mainly describes the sensitivity study of the physical process parameterization represented in the model. The systematic errors produced by the different physical parameterization schemes such as the land surface processes, convective precipitation, cloud-radiation transfer process, boundary layer process and large-scale terrain features have been identified based on multi-year and extreme flooding event simulations. A number of comparative experiments has shown that the mass flux scheme (MFS) and Betts-Miller scheme (BM) for convective precipitation, the LPMI (land surface process model I) and LPMII (land surface process model Ⅱ) for the land surface process, the CCM3 radiation transfer scheme for cloud-radiation transfer processes, the TKE (turbulent kinetic energy) scheme for the boundary layer processes and the topography treatment schemes for the Tibetan Plateau are suitable for simulations and prediction of the East Asia monsoon climate in rainy seasons. Based on the above sensitivity study, a modified version of the RegCM2 (RegCM_NCC) has been set up for climate simulations and seasonal predictions. 相似文献
12.
MODIFIED MASS FLUX CUMULUS CONVECTIVE PARAMETERIZATION SCHEME AND ITS SIMULATION EXPERIMENT—PART Ⅰ:MASS FLUX SCHEME AND ITS SIMULATION OF THE 1991 FLOOD EVENT* 下载免费PDF全文
下载免费PDF全文 Based on the existing cumulus convective parameterization schemes,a mass flux scheme (MFS) for cumulus convective parameterization has been successfully developed by reference to the work of Chen et al. (1996).The MFS is a comprehensive scheme.In MFS,not only the importance of the large-scale moisture convergence is taken into account,but also it includes the cumulus updrafts and downdrafts,cumulus-induced subsidence in the environmental air.entrainment,detrainment and evaporation.The interaction between the cumulus and the environment is described by using a one-dimensional bulk model.At the same time the scheme includes the penetrative and shallow convections.The MFS has been successfully incorporated into the regional climate model RegCM2 developed by NCAR.The new model has been applied to simulate summer monsoon characteristics and their variations of heavy rainfall process in the Changjiang-Huaihe River Basins for three months from May to July 1991.The results show that the new model can successfully simulate this rainfall prolonged process.By comparising the model outputs of RegCM2.using the Kuo scheme and the MFS.it is found that the MFS is better in simulating the surface temperature,rainfall position and amount,and rainfall duration. 相似文献
13.
In this research the dynamic downscaling method by Regional Climate Model (RegCM4.5) was used to assess the performance and sensitivity of seasonal simulated North and West of Iran (NI&WI) climate factors to different convection schemes, and transforms the large-scale simulated climate variables into land surface states over the North of Iran (NI) and West of Iran (WI). A 30-year (1986–2015) numerical integration simulation of climate over NI&WI was conducted using the regional climate model RegCM4.5 nested in one-way ERA-Interim reanalysis data. The Grell, Kuo and MIT-Emanuel cumulus convection with Holtslag and University of Washington (UW) planetary boundary layer (PBL) parameterization schemes were applied in the running of RegCM4.5 to test their capability in simulating precipitation and temperature in winter-spring (January–April) over NI and WI. The results demonstrated that the RegCM4.5 model has a good potential for simulating the variables and trend of surface temperature over the NI and WI region. Magnitude of the model bias for land surface temperature over different regions of Iran varies by convection parameterization schemes. In most cases, the root mean square error between post-processed simulated seasonal average temperature and observation value was less than 1 °C, but there is a systematic “cold bias”. In general, with respect to land surface temperature simulations, a better performance is obtained when using post-processing model’s data with Holtslag PBL-Grell and Holtslag PBL-Kuo configuration schemes, compared to the other simulations, over the NI&WI region. Also, the UW PBL convection schemes show a relatively excellent spatial correlations and normalized standard deviations closer to 1 for thirty-year seasonal land surface temperature anomalies over the entire NI&WI region. However, the simulation accuracy of model for precipitation is not as optimal as for temperature. The dominant feature in model simulations is a dry bias with the largest average value (∼1.04 mm/day) over NI region, while the lowest mean bias precipitation (∼−0.47 mm/day), mainly located in WI region. In the comparison of six configuration convection schemes, the Emanuel scheme has been proven to be the most accurate for simulating winter-spring seasonal mean precipitation over NI&WI region. The accuracy of the scheme also showed great difference in simulated station interpolation of precipitation, which urges the improvement for the simulation capability of spatial distribution of precipitation. In general, for seasonal variation of precipitation, the Emanuel convection with two (Holtslag, UW) PBL configuration schemes outperforms with a good correlation score between 0.7−0.8 and normalized standard deviations closer to 1. 相似文献
14.
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
15.
耦合不同陆面方案的WRF模式对2007年7月江淮强降水过程的模拟 总被引：10，自引：2，他引：8
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
16.
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
17.
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
18.
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 总被引：6，自引：3，他引：6
文中在综合比较各类积云对流参数化方案优缺点的基础上 ,主要参考陈伯民等修正的ECMWF质量通量积云参数化方案 ,对其进行简化和修改 ,发展了一个质量通量积云对流参数化方案 ,文中表示为 MFS(Mass Flux Scheme)。MFS是一种综合型的方案 ,既考虑了大尺度水汽辐合的重要性 ,又考虑了积云中的上升运动、下沉运动、环境中的补偿下沉运动 ,以及卷入、卷出和蒸发等 ,用总体云模式来描述积云与环境的相互作用 ,同时考虑了深对流和浅对流。将 MFS植入 NCAR区域气候模式 Reg CM2中 ,对 1 991年 5～ 7月江淮地区特大降水过程的夏季风气候特征和变化进行了模拟 ,并与 NCAR Reg CM2选用 Kuo方案 ,在同样初、边值条件和其它物理过程选择下的模拟结果进行了对比分析。分析结果表明 ,植入 MFS后的模式能够模拟这次极端的降水气候事件。在某些方面 ,如地表气温 ,降水的模拟上 ,植入 MFS后的模式的模拟结果要比原模式的结果更合理 相似文献