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1.
分辨率对区域气候极端事件模拟的影响 总被引：13，自引：2，他引：13
利用NCAR MM5V3对1999年6月长江流域的极端异常降水事件进行了模拟,主要研究不同水平和垂直分辨率对极端区域气候事件模拟的影响。数值模拟试验表明:模式能够模拟出极端强降水的主要分布特征;水平分辨率的提高降低了模式模拟的强降水偏差,对逐日降水变化的模拟更加合理,而垂直分辨率的提高基本上也都减小了模拟的强降水过程的偏差,改善对强降水的模拟能力;模式水平、垂直分辨率的提高在一定程度上增强了对强降水过程的模拟能力。水平分辨率的提高能够改善模式对海平面气压的模拟,而垂直分辨率的提高可以改善模式模拟的地面气温和低层环流。分辨率对中层大气环流的影响不是很敏感。不同积云对流参数化方案模拟的对流降水比率随水平分辨率的变化是不同的,Grell方案对流降水比例随分辨率的提高而增加,而Kain-Fritsch方案的结果相反。 相似文献
2.
一个载水预报模式的业务预报应用试验 总被引：8，自引：3，他引：5
该文在国家气象中心现行有限区域业务预报模式（LAM）的基础上,把模式的水平分辨率由1°×1°提高到0.5°×0.5°经纬度网格,垂直层次由15层变为20层。在原有物理过程中引入显式降水方案,并使用HLAFS业务系统的实时资料对1997年8月的一次登陆台风造成的强降水过程进行了个例预报试验,取得了较为合理的预报效果。 相似文献
3.
简要介绍了改进精细分辨率雷达所涉及的提高空间分辨率和智能化、快速扫描等技术。利用改进后的雷达精细分辨率数据和原始分辨率数据,对不同强天气类型的探测效果进行了对比分析,结果表明：精细分辨率数据可获得比原始分辨率数据更大的相对径向速度,辐合辐散和速度极值也更明显;获取更为清晰的超级单体结构以及龙卷涡旋特征和龙卷碎片特征等,更早识别出对流单体和雷暴云团;采用精细分辨率数据进行定量降水估计的精度与原始分辨率数据相当或略有提升。改进后精细分辨率数据具有更高的空间分辨率（双偏振）雷达观测特征,在对中小尺度强对流回波监测和识别的实际业务中具有较明显优势。 相似文献
4.
The fifth-generation Pennsylvania State University/NCAR Mesoscale Model Version 3 (MM5V3) was used to simulate extreme heavy rainfall events over the Yangtze River Basin in June 1999. The effects of model's horizontal and vertical resolution on the extreme climate events were investigated in detail. In principle, the model was able to characterize the spatial distribution of monthly heavy precipitation. The results indicated that the increase in horizontal resolution could reduce the bias of the modeled heavy rain and reasonably simulate the change of daily precipitation during the study period. A finer vertical resolution led to obviously improve rainfall simulations with smaller biases, and hence, better resolve heavy rainfall events. The increase in both horizontal and vertical resolution could produce better predictions of heavy rainfall events. Not only the rainfall simulation altered in the cases of different horizontal and vertical grid spacing, but also other meteorological fields demonstrated diverse variations in terms of resolution change in the model. An evident improvement in the simulated sea level pressure resulted from the increase of horizontal resolution, but the simulation was insensitive to vertical grid spacing. The increase in vertical resolution could enhance the simulation of surface temperature as well as atmospheric circulation at low levels, while the simulation of circulation at middle and upper levels were found to be much less dependent on changing resolution. In addition, cumulus parameterization schemes showed high sensitivity to horizontal resolution. Different convective schemes exhibited large discrepancies in rainfall simulations with regards to changing resolution. The percentage of convective precipitation in the Grell scheme increased with increasing horizontal resolution. In contrast, the Kain-Fritsch scheme caused a reduced ratio of convective precipitation to total rainfall accumulations corresponding to increasing horizontal resolution. 相似文献
5.
Summary ?This paper describes a numerical study of the major spiral rainband in typhoon Flo (1990) using the Meteorological Research
Institute Mesoscale Nonhydrostatic Model (MRI-NHM). The effects of precipitation schemes and horizontal resolution on the
representation of the simulated rainband are discussed.
Dynamic and thermodynamic structures of the simulated major rainband to the north of the storm center are well represented
in the model with a 5 km horizontal resolution. The structures are consistent with observational results reported for other
tropical cyclones. Among the realistic features are: a cold pool and convergence on the inner side of the band; convergence
above low-level inflow layers; and the outward slope of the updraft with height. The band is caused by the motion of the storm
through its surroundings where horizontal wind has vertical shear.
The simulation of the structure and precipitation pattern associated with the major rainband depends on the precipitation
scheme rather than the horizontal resolution. The band appears more realistic when using explicit cloud microphysics as a
precipitation scheme, rather than moist convective adjustment. This result is attributable to the difference in scheme triggering.
In the simulation with moist convective adjustment, the elimination of vertical instability in low-level atmosphere is excessive,
suppressing band formation. The overall structure of the band is also more realistic in the simulation using explicit cloud
microphysics, because a cold pool exists in the lower layers and the vertical axis of upward flow tilts outward. This result
suggests that prediction will partly depend on variables associated with cloud microphysics, such as the mixing ratio of cloud
water.
The horizontal grid distance, which varied between 5 and 20 km, quantitatively influenced the rainfall amount, although the
large-scale band structure remained unchanged. The rainfall amount increased as the grid interval was reduced from 20 to 10-km
but decreased as the interval was further reduced from 10 to 5 km.
Received March 20, 2001; revised August 20, 2001 相似文献
6.
Assimilation of NCEP multi-sensor hourly rainfall data using 4D-Var approach: A case study of the squall line on April 5, 1999 总被引：1，自引：0，他引：1
Summary ?NCEP multi-sensor hourly rainfall data were used for data assimilation and evaluation of quantitative precipitation forecasts
(QPFs) through a case study of a squall line on April 5, 1999. Improvements in QPFs were obtained through direct assimilation
of these rainfall observations using 4-dimensional variational assimilation (4D-Var). Inclusion of the observed no-rain information
was shown to be beneficial to QPFs. While the penalty constraint applying a digital filter was effective in removing high
frequency oscillations introduced by rainfall assimilation and produced a smoother “optimal” initial condition, its impact
on QPFs is mixed. Sensitivity studies indicated that the adjustments in the moisture and temperature fields resulted from
precipitation assimilation played a more important role than those of other state variables for improving QPFs.
Received October 27, 2001; accepted January 30, 2002 相似文献
7.
This paper investigates the effect of horizontal resolution on the precipitation of the super typhoon Rammasun (1409). The experiment uses WRF (V3.4) model with resolutions of 15 km, 9 km and 3 km. The results suggest that the simulated Rammasun rain band shapes and distributions at different horizontal resolutions are nearly the same. When the resolution is increased from 15 km to 9 km and then to 3 km, heavy precipitation is observed to spread in all directions from a concentrated distribution, especially when the resolution is increased from 9 km to 3 km. The 6h and 1h heavy precipitations also show a more significant comma-shape distribution. Moreover, the water vapor distribution shows the same characteristics as the heavy precipitation with a notably enhanced ascending movement and a decreased height of the strongest ascending movement. Of the three resolutions, the precipitation distribution simulated at 3 km resolution is the closest to the observed distribution; however, there is still a noticeable difference between the simulated precipitation and the actual observation. With the absence of the convection parameterization in the model, the precipitation distributions simulated at 9 km and 3 km resolutions demonstrate the same features as when the KF convection parameterization is applied. However, the simulated precipitations at these two resolutions are smaller than those obtained with the KF scheme. Meanwhile the difference between the simulated precipitations at these two resolutions is also smaller than that in the latter case. In general, when KF scheme is applied to the model, the simulation effect of Rammasun precipitation is better than that obtained without the convection parameterization scheme. 相似文献
8.
利用欧洲中期数值预报中心(ECMWF)高分辨率预报场(0.25°×0.25°)资料以及四川省加密自动站降水量资料对2011年汛期7—9月和2012年5—7月共计20例强降水个例进行湿螺旋度指标的统计分析,分别归纳总结出6和24 h内强降水发生发展及落区分布的判据指标。利用这些判据指标对2012年8月30日至9月1日及9月8日发生在四川盆地的两例强降水过程及2013年汛期6—8月暴雨个例进行检验并在汛期投入了业务预报工作。检验结果表明:低层700或850 hPa湿螺旋度正值区的分布对强降水落区分布指示较好;当强降水发生时,24 h时效预报的24~48 h 3 h间隔预报场湿螺旋度数量值超过了指标值并持续了2个时次以上,达到了强降水发生的要求;零场预报的0~24 h及12 h时效预报的12~36 h间隔3 h预报场任一时刻湿螺旋度数量值达到了6 h指标判据值,对其后6 h的暴雨落区有较好的指示作用,可作为短时临近预报的业务参考;湿螺旋度订正预报暴雨发生的TS评分远高于ECMWF模式,预报效果好。 相似文献
9.
WRF模式分辨率对新疆异常降雨天气要素模拟的影响 总被引：7，自引：2，他引：5
利用新一代中尺度气候数值模式WRF对中国西北干旱典型地区——新疆2000年10月的异常降雨事件进行模拟,主要研究了不同水平分辨率、垂直分辨率以及不同积云参数化过程对气温、降雨和土壤温度模拟的影响。结果表明：不同分辨率的模拟基本上均模拟出了地面气温的分布特征,且随着水平分辨率的提高,模式模拟能力显著提高,对地面气温值、分布范围的模拟渐趋合理,同时模式对于地形引起的温度分布变化的模拟更加趋近实际。水平分辨率、垂直分辨率的提高同样改善了模式对降水的模拟能力,分辨率的提高不仅改进了模式对降雨分布区模拟的精度,也增强了对于地形引起的降雨变异的模拟能力。在土壤温度模拟上,不同分辨率的试验均能模拟出土壤温度的分布特征,较高水平分辨率有利于描述土壤温度分布细节,但更容易出现“数值点风暴”现象。 相似文献
10.
对法国动力气象实验室发展的变网格全球大气环流模式LMDZ4在东亚地区的模拟性能进行评估。LMDZ4作为海气耦合模式IPSL-CM5A的大气模块,本文局地格点加密区域位于东亚上空,加密区外使用ERA-interim再分析资料进行驱动,积分时段为1979—2009年。通过对模式在东亚东部区域夏季气候的模拟能力评估,发现模式整体上能够真实地模拟出南亚高压、西风急流、西太副高、水汽输送以及夏季风等环流系统的气候平均态,地面雨带和气温的分布及极值中心都得到较好再现。同时模式仍显现一定的偏差,具体表现为,华南沿海的模拟偏冷偏湿,江淮流域偏暖偏干,而东北地区则偏暖偏湿,导致这种地面要素场偏差的原因来自于中上层环流场的系统性模拟偏差。例如,高层南亚高压、西风急流模拟偏弱,而印度季风和来自印度洋的水汽输送偏强,导致华南沿海降水偏多。西太平洋副高偏东偏弱,低纬东风带强度偏弱,西太平洋区域比湿偏小,使得东南风带来的水汽无法到达江淮流域。上述偏差的产生可能由于LMDZ4模式中的云参数化方案尚存在不足之处,使得云量的模拟偏少,并且该版本模式的垂直分辨率不足,限制了它对高层环流系统的模拟能力,增加了模式的系统误差。 相似文献
11.
应用NASA MERRA再分析资料对一次高原切变线的诊断分析 总被引：1，自引：1，他引：0
利用2016年6月29—30日地面及高空常规观测资料、CMORPH融合降水资料以及时空分辨率较高的NASA MERRA 0.625°×0.5°逐3 h再分析资料,对一次高原切变线过程进行了天气动力学诊断分析。运用广义位温、广义湿位涡和涡生参数等诊断量对切变线系统的生成及其降水分布进行分析。结果显示:广义位温等值线梯度大值区与大气水汽的聚集区相对应。切变线降水的发生、发展与广义湿位涡的分布及演变有较好的对应关系,低层大气广义湿位涡的正异常大值对降水发生有一定关联。广义湿位涡正负异常值之间的零线可较好表征高原切变线的位置。广义湿位涡中心强度对切变线生成与发展有一定指示意义。涡生参数可作为高原切变线生成和加强的一个明显前兆信号。 相似文献
12.
选取热带测雨卫星(Tropical Rainfall Measuring Mission,TRMM)微波成像仪(TRMM Microwave Imager,TMI)液态水路径(liquid water path,LWP)轨道像元数据为研究对象,探讨了将瞬时探测以及逐月的像元数据进行格点化(0.1°、0.25°、0.5°、1.0°和2.5°五种格点分辨率)时,格点数据的失真情况。对TMI瞬时探测的个例分析结果表明,细分辨率(0.1°、0.25°和0.5°)格点能保留原始像元数据的细节;而随着网格变粗,细节受到较大的平滑。因此对于中尺度到天气尺度的天气系统分析而言,将卫星轨道数据处理到网格尺度不大于0.5°的格点更合适。对逐月LWP像元资料格点化处理的分析表明,细分辨率格点能保留LWP空间分布细节,尽管5种分辨率下LWP的概率密度分布(probability density function,PDF)均相近。因此,对月尺度及以上的气候分析研究而言,格点尺度大小对卫星像元数据格点化的影响不显著。最后利用本实验室计算的TMI/LWP格点数据与欧洲中期数值预报中心再分析资料(European Centre for Medium-range Weather Forecasts Interim reanalysis,ERA-Interim)和NCEP再分析资料(NCEP Climate Forecast System Reanalysis,NCEP CFSR)进行了对比,发现两种再分析资料都高估了LWP;TMI/LWP格点数据与两种再分析资料LWP的多年变化趋势大致相同。 相似文献
13.
北京气候中心气候系统模式研发进展——在气候变化研究中的应用 总被引：4，自引：2，他引：2
吴统文 宋连春 李伟平 王在志 张华 辛晓歌 张艳武 张莉 李江龙 吴方华 刘一鸣 张芳 史学丽 储敏 张洁 房永杰 汪方 路屹雄 刘向文 魏敏 刘茜霞 周文艳 董敏 赵其庚 季劲钧 Laurent Li 周明煜 《气象学报》2014,72(1):12-29
较全面地介绍了北京气候中心气候系统模式(BCC_CSM)研发所取得的一些进展及其在气候变化研究中的应用,重点介绍了全球近280 km较低分辨率的全球海-陆-气-冰-生物多圈层耦合的气候系统模式BCC_CSM1.1和110 km中等大气分辨率的BCC_CSM1.1(m),以及大气、陆面、海洋、海冰各分量模式的发展。BCC_CSM1.1和BCC_CSM1.1(m)气候系统模式均包含了全球碳循环和动态植被过程。当给定全球人类活动导致的碳源排放后,就可以模拟和预估人类活动对气候变化的影响。BCC_CSM1.1和BCC_CSM1.1(m)已应用于IPCC AR5模式比较,为中外开展气候变化机理分析和未来气候变化预估提供了大量的试验数据。还介绍了BCC_CSM1.1和BCC_CSM1.1(m)参与国际耦合模式比较计划(CMIP5)的大量试验分析评估结果,BCC_CSM能够较好地模拟20世纪气温和降水等气候平均态和季节变化特征,以及近1000年的历史气候变化,所预估的未来100年气候变化与国际上其他模式的CMIP5试验预估结果相当。初步的分析表明,分辨率相对高的BCC_CSM1.1(m)在区域气候平均态的模拟上优于分辨率较低的BCC_CSM1.1。 相似文献
14.
利用NCEP 1°×1°格点再分析、FY-2E相当黑体亮温TBB和地面加密自动气象站等资料,分析了辽宁3次典型长历时强降水TBB值与降水强度的关系、中尺度环境场特征及维持机制,并初步建立了辽宁长历时强降水概念预报模型。结果表明:在副热带高压的形态、位置和强度有利于辽宁产生强降水的大尺度形势下,副热带高压西侧低空急流持续输送的充沛暖湿空气与高空干冷空气在同一地点长时间相互作用,为强降水的发生和维持提供了有利的环境背景条件。强降水持续时间与其上空的强垂直速度持续时间有很好的对应关系,强降水持续时高空一般为弱的不稳定或中性层结。强降水不仅可出现在对流云团发展旺盛的冷云区内部或边缘,也可发生在TBB值较小的暖云区内。TBB值的大小与降水强度没有必然的关系,但TBB值的快速减小都预示强降水即将发生。这些结论有利于深化认识辽宁地区长历时强降水的成因并为预报提供线索。 相似文献
15.
Impacts of a GCM＇s Resolution on MJO Simulation 总被引：3，自引：0，他引：3
Long-term integrations are conducted using the Spectral Atmospheric Model （referred to as SAMIL）, which was developed in the Laboratory for Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG） in the Institute of Atmospheric Physics （IAP）, with different resolutions to inves-tigate sensitivity of the Madden-Julian Oscillation （MJO） simulations to the model＇s resolution （horizontal and vertical）. Three resolutions of the model, R15L9, R42L9 and R42L26, with identical physical processes, all produced the basic observed features of the MJO, including the spatiotemporal space-time spectra and eastward propagation. No fundamental differences among these simulations were found. This indicates that the model resolution is not a determining factor for simulating the MJO. Detailed differences among these modeling results suggest, however, that model resolution can substantially affect the simulated MJO in certain aspects. For instance, at a lower horizontal resolution, high frequency disturbances were weaker and the structures of the simulated MJO were better defined to a certain extent. A higher vertical resolution led to a more realistic spatiotemporal spectrum and spatial distribution of MJO precipitation. Meanwhile, increasing the model＇s resolution improved simulation of the climatology. However, increasing the resolution should be based on improving the cumulus parameterization scheme. 相似文献
16.
We use the WRF (V3.4) model as the experimental model
and select three horizontal resolutions of 15, 9, and 3km to
research the influence of the model’s horizontal resolution on
the intensity and structure of the super-strong typhoon Rammasun
(1409) in 2014. The results indicate that the horizontal
resolution has a very large impact on the intensity and
structure of Rammasun. The Rammasun intensity increases as the
horizontal resolution increases. When the horizontal resolution
increases from 9km to 3km, the enhancement of intensity is more
obvious, but the strongest intensity simulated by 3km horizontal
resolution is still weaker than the observed strongest
intensity. Along with the increase of horizontal resolution, the
horizontal scale of the Rammasun vortex decreases, and the
vortex gradually contracts toward its center. The vortex
structure changes from loose to compact and deep. The maximum
wind radius, thickness of the eye wall, and outward inclination
of the eye wall with height decrease, and the wind in the inner
core region, updraft motion along the eye wall, and strength of
the warm core become stronger. Additionally, the pressure
gradient and temperature gradient of the eye wall region
increase, and the vortex intensity becomes stronger. When the
horizontal resolution increases from 9km to 3km, the change in
the Rammasun structure is much larger than the change when the
horizontal resolution increases from 15km to 9km. When the model
does not employ the method of convection parameterization, the
Rammasun intensity simulated with 3km horizontal resolution is
slightly weaker than the intensity simulated with 3km horizontal
resolution when the Kain–Fritsch (KF) convection
parameterization scheme is adopted, while the intensity
simulated with 9km horizontal resolution is much weaker than the
intensity simulated with 9km horizontal resolution when the KF
scheme is adopted. The influence of the horizontal resolution on
the intensity and structure of Rammasun is larger than the
influence when the KF scheme is adopted. 相似文献
17.
用中国科学院大气物理研究所高分辨率、自由表面热带海洋环流模式对厄尼诺/南方涛动(El/Southern Oscillation)循环中另一重要位相La Niña事件进行了数值模拟研究。模式区域为南北纬30°之间的热带太平洋,经纬圈水平方向分辨率分别为2°和1°,垂直方向分为不等距的14层;模式中考虑了盐度并引入与洋流切变和层结稳定度有关的垂直扩散参数化方案。在观测到的海表风应力、热量和淡水通量(蒸发与降水之差)驱动下,所发展的模式从1984年积分到1989年。本文给出模式对近十几年来最强的1988年La Niña事件进行数值模拟的结果,着重分析La Niña期间热带太平洋海面起伏、流场和温度场时空演变,以及La Niña和El期间变量场时空结构差别。文中还进行了模式结果和一些观测资料间的比较。 相似文献
18.
基于GRAPES区域中尺度数值预报系统(GRAPES_MESO),针对700 hPa、500 hPa和200 hPa的位势高度场H,温度场T,风场纬向分量U,经向分量V和地面降水场,在给定的模式物理过程下,分别考察了时间步长和空间分辨率对于模式预报效果的影响。研究结果表明,空间分辨率(0.3°×0.3°)相同时,各变量在不同层次的预报几乎都存在最优时间步长使得预报技巧最高,初步说明最优时间步长理论在复杂的偏微分方程组中的适用性。随后,将空间分辨率为0.3°×0.3°时最优时间步长(240 s)的预报结果与当前业务中(空间分辨率为0.15°×0.15°、时间步长为90 s)的预报结果进行比较,发现前者的变量H、T、U、V和地面降水场的预报技巧均高于后者,表明并不是空间分辨率越高预报效果越好。 相似文献
19.
2019年超强台风“利奇马”引发浙江特大暴雨过程分析 总被引：1，自引：0，他引：1
利用NCEP FNL 0.25°×0.25°的再分析资料和浙江省中尺度气象站降水资料,从产生强降水的条件来对“利奇马”特大暴雨过程进行诊断分析。结果表明:(1)强降水主要集中在近台风中心的西南部分及其稍远的北部,其中近台风中心为眼壁降水,北部为螺旋云带降水;(2)850~925 hPa水汽通量辐合中心与暴雨落区一致,水汽辐合强度差异是造成台风眼壁强降水落区差异的关键;(3)台风强度大时近中心上升运动强烈,正垂直螺旋度中心值的减小和中心下降对应强降水的发生,低层正螺旋度和高层负螺旋度中心的重叠区对对流性降水落区有一定的指示;(4)本次过程地形增益最明显地区在台州北部,在水汽条件处于劣势情况下出现降水副中心。 相似文献
20.
Summary An attempt has been made to simulate the unprecedented heavy precipitation of 94.4 cm in a day over Santacruz, Mumbai during
0300 UTC 26 July to 0300 UTC 27 July 2005. Three experiments have been conducted using Advanced Regional Prediction System
model developed by Center for Analysis and Prediction of Storms of Oklahoma University, USA. In first experiment the model
input at large domain size has been obtained using NCEP/NCAR reanalysis data at 2.5° × 2.5° lat.–lon. resolution. In other
two experiments model input at large as well as at small domain sizes, have been obtained from NCEP/NCAR FNL data of 1° ×
1° lat.–lon. resolution. In all three experiments model’s horizontal resolution is 40 km and integration period is 30 hours
from 0000 UTC 26 July 2005. Based on the temporal distribution of observed rainfall rates it is considered that the rainfall
of 38.1 cm during 0900–1200 UTC on 26 July could be due to cloud burst phenomenon and 56.3 cm from 1200 UTC of 26 July to
0300 UTC of 27 July has been due to continuous regeneration of thunderstorm activity under influence of mesoscale cloud complex.
It is found that model forecast of rainfall in first experiment was qualitatively as well as quantitatively very poor. Among
other two, experiment with large domain size has predicted better rainfall values and location compared to the experiment
with small domain size. The larger domain has produced rainfall of 41 cm as against observed rain rate of 56.3 cm. during
1200 UTC of 26 July to 0300 UTC of 27 July. Divergence, vorticity, vertical velocity and moisture parameters are examined
in relation with the various stages of the event. The maximum values of convergence, vorticity and moisture fluxes precede
the initial phase of mature stage, however vertical velocity follows the later phase of mature stage. Vorticity budget over
the location of maximum rainfall, revealed the significant role of tilting term in maintenance and dissipation of the cloud
complex responsible for the event. The model has simulated mixing ratios of ice, snow and hail up to height of 15 km which
matches with the observations that clouds reaching up to 15 km were present at the time of event of heavy precipitation. 相似文献