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1.
In this study,an extreme rainfall event that occurred on 25 May 2018 over Shanghai and its nearby area was simulated using the Weather Research and Forecasting model,with a focus on the effects of planetary boundary layer(PBL)physics using double nesting with large grid ratios(15:1 and 9:1).The sensitivity of the precipitation forecast was examined through three PBL schemes:the Yonsei University Scheme,the Mellor?Yamada?Nakanishi Niino Level 2.5(MYNN)scheme,and the Mellor?Yamada?Janjic scheme.The PBL effects on boundary layer structures,convective thermodynamic and large-scale forcings were investigated to explain the model differences in extreme rainfall distributions and hourly variations.The results indicated that in single coarser grids(15 km and 9 km),the extreme rainfall amount was largely underestimated with all three PBL schemes.In the inner 1-km grid,the underestimated intensity was improved;however,using the MYNN scheme for the 1-km grid domain with explicitly resolved convection and nested within the 9-km grid using the Kain?Fritsch cumulus scheme,significant advantages over the other PBL schemes are revealed in predicting the extreme rainfall distribution and the time of primary peak rainfall.MYNN,with the weakest vertical mixing,produced the shallowest and most humid inversion layer with the lowest lifting condensation level,but stronger wind fields and upward motions from the top of the boundary layer to upper levels.These factors all facilitate the development of deep convection and moisture transport for intense precipitation,and result in its most realistic prediction of the primary rainfall peak. 相似文献
2.
不同边界层参数化方案对东亚夏季风气候模拟的对比研究 总被引：6，自引：3，他引：3
用WRF v3.2.1中尺度预报模式和NCEP/NCAR再分析资料,对比研究了WRF模式中5个不同边界层参数化方案对东亚夏季风气候的模拟效果。结果表明:WRF模式对各边界层参数化方案均较为敏感,采用不同的边界层参数化方案对模拟区域内的夏季降水、气温、环流等气候要素均可产生明显影响。选取MYJ方案和QNSE方案对500 h Pa夏季平均环流的模拟效果较好,YSU方案和QNSE方案对夏季平均日降水量模拟与再分析资料更吻合,YSU方案和MYNN2.5方案对中国东部2 m气温的模拟结果较好。不同边界层参数化方案模拟结果都显示出由于副热带高压偏强,使副热带高压第2次北跳后停留时间过短,导致长江中下游降水偏少,华北地区降水增多。通过比较YSU和QNSE边界层方案,发现YSU方案相比QNSE方案的降水差异,是由于850 h Pa水汽输送造成的。在中国大部分地区YSU方案的2 m温度比QNSE方案高,并且地面2 m气温和降水存在一定对应关系。因此合理选取边界层参数化方案可以提高数值模拟的准确性。 相似文献
3.
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
4.
区域气候模式对不同的积云参数化方案在青藏高原地区气候模拟中的敏感性研究 总被引：4，自引：3，他引：1
本文使用MIROC3.2_hires模式输出资料作为RegCM3 (The ICTP Regional Climate Model,V3.0)初边界资料,对RegCM3中常用的3种积云参数化方案Anthes-Kuo (AK)、Grell-Fritsch&Chappell (GFC)和MIT-Emanuel (MIT)方... 相似文献
5.
不同边界层方案对一次华北暴雨数值模拟的敏感性研究 总被引：1，自引：1，他引：0
以2010年8月17—19日华北地区的暴雨事件为研究对象,采用中尺度数值模式WRF,通过8个数值实验测试暴雨事件模拟结果对不同边界层方案的敏感性。结果表明,采用不同边界层方案的模拟结果存在明显差异。分辨率为12 km时,7个边界层方案实验均模拟出类似观测的四处较强降水,但模拟得到的降水强度和强降水中心位置与实况有所差异,NOPBL实验模拟的雨带收缩,降水相对其他模拟实验较少且更为集中。分辨率为4 km时,采用边界层方案的7个实验均可见小尺度降水结构,模拟出较多虚假降水中心,而在NOPBL试验中降水的小尺度结构不明显。检验表明:分辨率为12 km时,MYJ试验的TS评分、相关系数和误差分析等整体表现最优,分辨率为4 km时,Bou Lac试验整体表现最优。与NOPBL试验相比,加入MYJ边界层方案后,模拟的水汽输送增加、上升运动及涡散度绝对值增大。 相似文献
6.
物理过程参数化方案对中尺度暴雨数值模拟影响的研究 总被引：48，自引：5，他引：43
利用中尺度非静力MM 5模式和中国 2 0 0 1年 8月的 4个暴雨个例 ,研究了非绝热物理过程对中国暴雨动力和热力场预报的影响 ,深入分析了对流参数化方案在中尺度暴雨预报中的作用 ,讨论了利用模式扰动方法开展中国暴雨集合预报的可行性。结果表明 ,在短期数值预报中 ,非绝热物理过程对高度场预报影响较小 ,但边界层方案和对流参数化方案对产生暴雨的 3个基本条件即水汽通量散度、垂直速度、不稳定层结的影响很明显。不同对流参数化方案所预报的中尺度热力、动力场离差的结构特征与所预报降水的离差特征相似 ,且主要是在模式积分初期迅速增加 ,其后即趋于稳定。对中国热力场较均匀的暴雨过程 ,可以通过扰动模式的边界层和对流参数化方案 ,构造集合预报模式 相似文献
7.
Alejandro Di Luca Emmanouil Flaounas Philippe Drobinski Cindy Lebeaupin Brossier 《Climate Dynamics》2014,43(9-10):2349-2375
The use of high resolution atmosphere–ocean coupled regional climate models to study possible future climate changes in the Mediterranean Sea requires an accurate simulation of the atmospheric component of the water budget (i.e., evaporation, precipitation and runoff). A specific configuration of the version 3.1 of the weather research and forecasting (WRF) regional climate model was shown to systematically overestimate the Mediterranean Sea water budget mainly due to an excess of evaporation (~1,450 mm yr?1) compared with observed estimations (~1,150 mm yr?1). In this article, a 70-member multi-physics ensemble is used to try to understand the relative importance of various sub-grid scale processes in the Mediterranean Sea water budget and to evaluate its representation by comparing simulated results with observed-based estimates. The physics ensemble was constructed by performing 70 1-year long simulations using version 3.3 of the WRF model by combining six cumulus, four surface/planetary boundary layer and three radiation schemes. Results show that evaporation variability across the multi-physics ensemble (～10 % of the mean evaporation) is dominated by the choice of the surface layer scheme that explains more than ～70 % of the total variance and that the overestimation of evaporation in WRF simulations is generally related with an overestimation of surface exchange coefficients due to too large values of the surface roughness parameter and/or the simulation of too unstable surface conditions. Although the influence of radiation schemes on evaporation variability is small (～13 % of the total variance), radiation schemes strongly influence exchange coefficients and vertical humidity gradients near the surface due to modifications of temperature lapse rates. The precipitation variability across the physics ensemble (～35 % of the mean precipitation) is dominated by the choice of both cumulus (～55 % of the total variance) and planetary boundary layer (～32 % of the total variance) schemes with a strong regional dependence. Most members of the ensemble underestimate total precipitation amounts with biases as large as 250 mm yr?1 over the whole Mediterranean Sea compared with ERA Interim reanalysis mainly due to an underestimation of the number of wet days. The larger number of dry days in simulations is associated with a deficit in the activation of cumulus schemes. Both radiation and planetary boundary layer schemes influence precipitation through modifications on the available water vapor in the boundary layer generally tied with changes in evaporation. 相似文献
8.
中国夏季不同强度降水模拟对不同积云对流参数化方案的敏感性研究 总被引：3，自引：2，他引：1
利用PσRCM9区域气候模式, 分析了中国夏季不同强度降水模拟对不同积云对流参数化方案的敏感性。结果表明, 采用四种积云对流参数化方案, 模式能够模拟出小雨、 大雨和暴雨的雨量百分比和雨日百分比空间分布的一致性特征, 但不能模拟出中雨雨量百分比和雨日百分比空间分布的相似性, 这是由于模式不能模拟中雨雨量百分比的空间分布形式所致。还发现模拟的我国夏季降水以小雨和中雨为主, 四种积云对流参数化方案均低估了中国夏季大雨和暴雨对总降水的贡献, 尤其是在我国西部、 东北和华北地区更明显。不同积云对流参数化方案下模拟的极端强降水阈值的空间分布形式基本与观测一致, 但强度与观测存在较大差异。相比较而言, Grell方案较Kuo、 Anthes-Kuo和Betts-Mille积云对流参数化方案更适合中国东南部地区夏季极端强降水的模拟。 相似文献
9.
In this study, the accuracy of a Pennsylvania State University-National Center for Atmospheric Research mesoscale model (PSU/NCAR MM5) for predicting heavy summer precipitation over the Korean Peninsula was investigated. A total of 1800 simulations were performed using this model for 30 heavy rainfall events employing four cumulus parameterization schemes (CPS), two grid-scale resolvable precipitation schemes (GRS), and two planetary boundary layer (PBL) schemes in three model resolutions (90 km, 30 km, and 10 km). The heavy rainfall events were mesoscale convective systems developed under the influence of mid-latitude baroclinic systems with low-level moisture transport from the ocean. The predictive accuracy for maximum rainfall was approximately 80% for 10-km resolution and was 60% for 30-km resolution. The predictive accuracy for rainfall position extended to ～150 km from the observed position for both resolutions. Simulated rainfall was most sensitive to CPS, then to PBL schemes, and then to GRS. In general, the Grell (GR) scheme and the Anthes and Kuo (AK) scheme showed a better prediction capability for heavy rainfall than did the Betts-Miller (BM) scheme and the Kain-Fritsch (KF) scheme. The GR scheme also performed well in the 24-h and 12-h precipitation predictions: the parameterized convective rainfall in GR is directly related to synoptic-scale forcing. The models without CPS performed better for rainfall amounts but worse for rainfall position than those with CPS. The MM5 model demonstrated substantial predictive capacity using synoptic-scale initial conditions and lateral boundary data because heavy summer rainfall in Korea occurs in a strong synoptic-scale environment. 相似文献
10.
本文在十一层原始方程模式中引入Fritsch-Chappell一维云模式，对1982年5月12日江淮气旋上中尺度系统进行了模拟试验，分析表明:Fritsch-Chappell一维云模式对深厚积云的考虑细致合理，比郭晓岚积云参数化方案优越，它能模拟出中尺度系统的一些特征。通过数值计算发现:中尺度江淮气旋是对流层低层的天气系统，气压场上具有中尺度低压的某些特征；对流天气的出现，使得中尺度江淮气旋得到发展，但这种发展有一个变化过程，在对流发展加强时，对流引起的动量变化以及下沉气流造成的低层冷却作用，使其有一个暂时的减弱过程，当对流运动趋于减弱时，气旋才得以发展。 相似文献
11.
不同参数化方案对长江中游汛期降水模式预报试验 总被引：2，自引：2，他引：0
利用中尺度模式多个物理过程组合成不同预报方案,对长江中游汛期降水预报进行了对比试验.试验结果表明,使用不同物理过程参数化方案对长江中游汛期降水的预报效果存在差异,这种差异随降水预报量级的提高而愈加明显;而就试验而言,Grell积云对流参数化方案与Blackadar边界层参数化方案的组合预报效果相对较好;就单个降水个例而言,预报效果相对好的参数化方案存在不确定性,集合平均预报相对稳定且优于大多数方案,其对降水评分的改进尤其体现在暴雨以下量级的预报中. 相似文献
12.
M. A. Tadross W. J. Gutowski Jr B. C. Hewitson C. Jack M. New 《Theoretical and Applied Climatology》2006,86(1-4):63-80
Summary Two cumulus convection and two planetary boundary layer schemes are used to investigate the climate of southern Africa using
the MM5 regional climate model. Both a wet (1988/89) and a dry (1991/92) summer (December–February, DJF) rainfall season are
simulated and the results compared with three different observational sources: Climate Research Unit seasonal data (precipitation,
2 m surface temperature, number of rain days), satellite-derived diurnal precipitation and the Surface Radiation Budget diurnal
short-wave fluxes and optical depth.
Using the ETA model boundary layer in MM5 simulates too much incident short-wave radiation at the surface at 12 UTC, whereas
the medium range forecast model boundary layer yields a diurnal cycle of short-wave radiation closer to the observed. The
Betts-Miller convection scheme in MM5 simulates peak rainfall later in the day and less rain days than observed, whereas when
using the Kain-Fritsch convection scheme a peak rainfall earlier in the day and more rain days than observed are simulated.
The intensity of the hydrological cycle is therefore dependent on the choice of convection scheme, which in turn is further
modified by the boundary layer scheme. Precipitation during the wet 1988/89 season is reasonably captured by most simulations,
though using the Betts-Miller scheme more accurately simulates rainfall during the dry 1991/92 season. Mean DJF biases in
the surface temperature and diurnal temperature range are consistent with biases in the number of rain days and the diurnal
cycles of surface moisture and energy. 相似文献
13.
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
14.
为评估CWRF模式的降尺度能力和其热带气旋模拟对物理参数化方案的敏感性,本文利用ERI再分析资料驱动CWRF在30km网格上对1982-2016年中国近海热带气旋开展了一次集合模拟.结果表明:CWRF与ERI均能模拟出热带气旋的季节变化和年际变化形势且均存在低估,但相较ERI,CWRF的降尺度技术和集合模拟可以再现更多的热带气旋,显著减少低估.年际变化结果提升最为明显,它对积云方案最为敏感,其次是边界层,陆面和辐射方案,对云和微物理方案较弱.该研究为应用CWRF理解和预报热带气旋提供了参考. 相似文献
15.
Uncertainties in simulating the seasonal mean atmospheric water cycle in Equatorial East Africa are quantified using 58 one-year-long experiments performed with the Weather Research and Forecasting model (WRF). Tested parameters include physical parameterizations of atmospheric convection, cloud microphysics, planetary boundary layer, land-surface model and radiation schemes, as well as land-use categories (USGS vs. MODIS), lateral forcings (ERA-Interim and ERA40 reanalyses), and domain geometry (size and vertical resolution). Results show that (1) uncertainties, defined as the differences between the experiments, are larger than the biases; (2) the parameters exerting the largest influence on simulated rainfall are, in order of decreasing importance, the shortwave radiation scheme, the land-surface model, the domain size, followed by convective schemes and land-use categories; (3) cloud microphysics, lateral forcing reanalysis, the number of vertical levels and planetary boundary layer schemes appear to be of lesser importance at the seasonal scale. Though persisting biases (consisting of conditions that are too wet over the Indian Ocean and the Congo Basin and too dry over eastern Kenya) prevail in most experiments, several configurations simulate the regional climate with reasonable accuracy. 相似文献
16.
Barry H. Lynn Cynthia Rosenzweig Richard Goldberg David Rind Christian Hogrefe Len Druyan Richard Healy Jimy Dudhia Joyce Rosenthal Patrick Kinney 《Climatic change》2010,99(3-4):567-587
The Mesoscale Modeling System Version 5 (MM5) was one-way nested to the Goddard Institute for Space Studies global climate model (GISS GCM), which provided the boundary conditions for present (1990s) and future (IPCC SRES A2 scenario, 2050s) five-summer “time-slice” simulations over the continental and eastern United States. Five configurations for planetary boundary layer, cumulus parameterization, and radiation scheme were tested, and one set was selected for use in the New York City Climate and Health Project—a multi-disciplinary study investigating the effects of climate change and land-use change on human health in the New York metropolitan region. Although hourly and daily data were used in the health project, in this paper we focus on long-term current and projected mean climate change. The GISS-MM5 was very sensitive to the choice of cumulus parameterization and planetary boundary layer scheme, leading to significantly different temperature and precipitation outcomes for the 1990s. These differences can be linked to precipitation type (convective vs. non-convective), to their effect on solar radiation received at the ground, and ultimately to surface temperature. The projected changes in climate (2050s minus 1990s) were not as sensitive to choice of model physics combination. The range of the projected surface temperature changes at a given grid point among the model versions was much less than the mean change for all five model configurations, indicating relative consensus for simulating surface temperature changes among the different model projections. The MM5 versions, however, offer less consensus regarding 1990s to 2050s changes in precipitation amounts. All of the projected 2050s temperature changes were found to be significant at the 95th percent confidence interval, while the majority of the precipitation changes were not. 相似文献
17.
Two surface layer parameterization schemes along with five planetary boundary layer (PBL) schemes in the Weather Research and Forecasting model (WRF) are analyzed in order to evaluate the performance of the WRF model in simulating the surface variables and turbulent fluxes over an Indian sub-continent region. These surface layer schemes are based on the fifth-generation Pennsylvania State University—National Center for Atmospheric Research Mesoscale Model (MM5) parameterization; (a) Old MM5 scheme having Businger-Dyer similarity functions and (b) revised MM5 scheme utilizing the functions that are valid for full ranges of atmospheric stabilities. The study suggests that each PBL scheme can reproduce the diurnal variation of 2 m temperature, momentum flux and sensible heat flux irrespective of the surface layer scheme used for the simulations. However, a comparison of model-simulated values of surface variables and turbulent fluxes with observed values suggests that each PBL scheme is found to systematically over-estimate the nocturnal 2 m temperature and 10 m wind speed with both the revised and old schemes during stable conditions. 相似文献
18.
The southwestern coast of the Caspian Sea often experiences heavy snowfall during winter season due to the lake effect. The accurate estimation of snowfall in this region is still a challenge for weather forecasters. This study attempts to investigate the simulation of lake-effect snow (LES) event occurring along the southwest coastline of the Caspian Sea from 31 January to 4 February 2014 using Weather Research and Forecasting (WRF) model. The study evaluates the sensitivity of four microphysics (WSM6, Goddard, Morrison, and Thompson) schemes and two planetary boundary layer (PBL) schemes (the Yonsei University (YSU) and the Mellor-Yamada-Janjic (MYJ)), yielding eight distinct combinations. The results indicated that all the simulations overestimated the precipitation. However, the best configurations for estimation of precipitation and snow in terms of their spatiotemporal variation were the Morrison-MYJ and the Goddard-MYJ, respectively. Analyses of the vertical profiles of hydrometeor species showed that the combination of Goddard and MYJ schemes created more snow and graupel than the other configurations. Although the combination of WSM-MYJ schemes revealed the least bias, it was not appropriate for the prediction of snow. A comparison of the two boundary layer schemes showed that the MYJ scheme simulated better intensity and distribution of precipitation than the YSU scheme compared to observations. Also, the maximum radar reflectivity of the model output was useful for identifying the location of maximum precipitation. 相似文献
19.
Improvements in WRF simulation skills of southeastern United States summer rainfall: physical parameterization and horizontal resolution 总被引：2，自引：0，他引：2
Realistic regional climate simulations are important in understanding the mechanisms of summer rainfall in the southeastern United States (SE US) and in making seasonal predictions. In this study, skills of SE US summer rainfall simulation at a 15-km resolution are evaluated using the weather research and forecasting (WRF) model driven by climate forecast system reanalysis data. Influences of parameterization schemes and model resolution on the rainfall are investigated. It is shown that the WRF simulations for SE US summer rainfall are most sensitive to cumulus schemes, moderately sensitive to planetary boundary layer schemes, and less sensitive to microphysics schemes. Among five WRF cumulus schemes analyzed in this study, the Zhang–McFarlane scheme outperforms the other four. Further analysis suggests that the superior performance of the Zhang–McFarlane scheme is attributable primarily to its capability of representing rainfall-triggering processes over the SE US, especially the positive relationship between convective available potential energy and rainfall. In addition, simulated rainfall using the Zhang–McFarlane scheme at the 15-km resolution is compared with that at a 3-km convection-permitting resolution without cumulus scheme to test whether the increased horizontal resolution can further improve the SE US rainfall simulation. Results indicate that the simulations at the 3-km resolution do not show obvious advantages over those at the 15-km resolution with the Zhang–McFarlane scheme. In conclusion, our study suggests that in order to obtain a satisfactory simulation of SE US summer rainfall, choosing a cumulus scheme that can realistically represent the convective rainfall triggering mechanism may be more effective than solely increasing model resolution. 相似文献
20.
MM4模式积云参数化方案的改进和检验Ⅱ：改进模式的检验试验 总被引：4，自引：1，他引：4
为了检验用Fritsch-Chappell积云参数化方案改进的MM4模式^[1]对梅雨锋暴雨系统的模拟能力，初步确定该模型的稳定性，可靠性，用不同的侧边界条件，地形条件，行星边界层参数化方法进行了模拟试验，并将模拟结果与采用Kuo-Anthes积云参数化方案的模式模拟结果分别进行了比较，结果表明，改进模式对高度场和降水的预报均有改善，并能预报出一些细致特征，此外，改进模式对侧边界条件和地形极为敏感，而对行星边界层参数化方法的敏感性较弱，因此在模式侧边界条件选取和地形处理方面应十分谨慎。 相似文献