共查询到18条相似文献，搜索用时 332 毫秒
1.
利用不同水平分辨率下的中尺度数值模式WRF模拟1319号超强台风"天兔",以研究模式水平分辨率对台风强度和微结构(包括动力和微物理)的影响。模拟结果表明:不同水平分辨率(1 km、2 km、3 km、4km、5 km)模拟的台风路径差异不大,且均与实况基本相同;不同水平分辨率对台风强度和微结构的模拟效果影响较大,其中以对10 m最大风速、垂直运动和降水强度的影响为最大。将模式水平分辨率提高到1 km有助于改善台风强度和微结构的模拟效果。在较低分辨率下,台风非对称性较明显、眼墙倾斜程度较大和海表水汽通量较小等结构特征共同使得台风强度较小。 相似文献
2.
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
3.
强台风“海葵”(1211)近海急剧增强的数值研究 总被引：2，自引：0，他引：2
近海台风强度急剧增强是预报中的难点。使用新一代中尺度WRF模式对台风“海葵”(1211)近海强度急剧增强过程进行数值模拟,并对数值模拟结果展开分析,研究引起台风强度突变的可能机理及相应结构变化。模拟结果表明,台风“海葵”的急剧增强与低层水汽输入的突然增加以及有利的高、低层辐散、辐合流场配置密切相关,且在“海葵”台风强度迅速增强的前6 h其高低层辐合、辐散流场呈现同时增强。台风结构变化的分析表明,在台风急剧增强时段台风结构趋于对称化,且低层眼壁范围小,高层眼壁范围向外扩展。伴随着台风强度增强,径向风速和切向风速也处在增大过程中,特别是台风急剧增强阶段,径向风速和切向风速增大更明显。另外,暖心强度逐渐加强,且暖心范围明显扩大并向低层扩展。同时随着台风强度的增强,垂直上升运动也逐渐增强。台风的这些结构变化都有利于其强度的维持和发展。 相似文献
4.
随着计算能力的提升,台风数值模拟大量采用了大涡尺度模拟,其水平分辨率已达到数10 m的量级,而垂直分辨率提升不大,其问题是数值模式的垂直分辨率对台风大涡模拟的影响如何?因此,本文利用WRF(Weather Research and Forecasting)模式开展理想台风模拟,在不同的模式垂直层次(42,69和90层)情况下,研究并讨论数值模式垂直分辨率对台风大涡模拟的影响。结果表明,42层的垂直分辨率明显不足,而69层和90层的垂直分辨率则都能模拟出细致的台风边界层小尺度结构,龙卷尺度涡旋出现较多。与69层试验相比,90层试验模拟的台风强度要弱、龙卷尺度涡旋数量要少,但模拟的台风强度更稳定,模拟的小尺度涡旋也更精细。 相似文献
5.
不同垂直分辨率对台风数值模拟影响的敏感性试验 总被引：1，自引：0，他引：1
利用新一代数值预报模式ARW(Advance Research WRF),模拟试验了在不同垂直分辨率条件下模式对"罗莎"台风的预报性能。试验结果表明,数值模式的垂直分辨率变化对台风路径预报效果的影响不大,但对台风强度和结构的预报效果有明显影响。但是,对于一定的水平分辨率而言,有一个与之匹配的垂直分辨率,垂直分辨率低于或者高于这个相匹配的阈值,模式的预报性能都会下降。 相似文献
6.
利用ARW-WRF模式,以垂直方向40个模式层（对低层加密）、水平方向最高1 km的分辨率,对台风桑美（2006）进行数值模拟,模拟结果与实况基本一致。基于台风桑美（2006）1 km分辨率的模拟结果,对台风低层（海面或地表以上1500 m以下）风场结构进行了分析。结果表明,在台风登陆前,其最大风速半径附近存在水平风速在垂直方向有很强变化的风廓线,该类型风廓线的最大风速高度有明显变化,表现出类似急流的特征;而台风登陆后,其水平风速垂直变化明显减弱,即风廓线类型发生较大变化;另有一种水平风速在高层少变的风廓线类型在台风中是普遍存在的。还根据高层和低层两个切变因子,将台风登陆前的风廓线分为急流型、普通型和过渡型,并进一步分析各类风廓线在台风中出现的位置和急流高度。对急流型风廓线的形成原因也进行了初步探讨,结果表明,超/次梯度风在垂直方向上的变化是形成急流型风廓线的原因,而外围绝对角动量的输送在其中起关键作用。 相似文献
7.
利用非静力中尺度模式WRF模拟了台风Chanchu（0601）,模式再现了台风Chanchu的路径、强度及结构。利用模式资料分析了台风Chanchu发展增强过程中其流出层和流入层风速的日变化特征、造成该日变化特征的机制及其对台风强度的影响。分析表明:台风Chanchu流出层和流入层的风速均存在显著的日变化特征,表现在低层径向入流和高层径向出流在夜间至清晨明显增强,在白天增加缓慢;切向风变化趋势同径向风类似,位相较径向风落后约6 h。通过对比夜间和白天云顶温度（CTT）和垂直速度频率（CFADS）的分布,发现夜间对流较白天更加活跃,这与夜间云顶冷却所导致的静力稳定度降低有关。利用切向风倾向方程进行收支分析,结果显示太阳辐射日变化通过调节对流日变化,引起高低层径向气流的日变化,进而造成切向风速的日变化,从而影响台风强度,在一定程度上揭示了日变化对台风强度变化的指示意义。 相似文献
8.
利用非静力中尺度WRF模式模拟的台风Chanchu(0601)的输出资料,探讨了Chanchu减弱变性过程的强度及结构变化。分析结果表明:在台风Chanchu北移过程中,高层的暖心被破坏,强度快速减弱,眼壁对流发展高度降低,眼壁对流由对称结构演变为非对称,内核对流减弱。此减弱变性过程与惯性稳定度减小、垂直风切变增强、低层锋生等环境要素有关。惯性稳定度与台风强度变化一致,随着惯性稳定度降低,最大切向风减弱并不断外扩,Rossby变形半径增大从而潜热释放不集中难以维持台风强度,台风减弱;同时,内核区的高层暖心更易径向频散,从而高层暖心难以维持;环境的垂直风切变增强使台风的斜压性增强,台风垂直结构的倾斜度增大,对流发展高度降低;低层冷空气侵入台风中心趋于填塞,也利于台风强度减弱;台风登陆以后冷暖空气对比导致的锋生使得不稳定能量释放从而重新加强了Chanchu环流内的中低层对流活动,但较台风最强时刻而言对流强度减弱。总体减少的对流和降低的对流高度,导致潜热能释放减小,其向心输送也减少,不足以维持强暖心结构,最终使得台风减弱并变性。 相似文献
9.
10.
积云参数化和分辨率对MJO数值模拟的影响 总被引：3，自引：1，他引：2
用中国科学院大气物理研究所发展的一个大气环流模式,使用不同的积云参数化方案和分辨率进行了6个模拟试验,考察了积云参数化方案和模式分辨率对热带大气季节内振荡（MJO）模拟的影响。结果显示：积云参数化方案和分辨率都会影响MJO的模拟。但积云参数化方案决定了模式对MJO模拟的基本能力,决定了模拟的MJO的基本特征。分辨率的变化并不能使模拟的MJO发生本质的改变,分辨率的作用更多的是对MJO的模拟起一定的调制作用,而这种调制作用又受到积云参数化方案的制约。在改进积云参数化方案的基础上提高模式的分辨率会在某些方面改善MJO的模拟。但是分辨率的提高需要同时提高水平分辨率和垂直分辨率,单独提高水平分辨率会降低模式模拟MJO的能力,引入更多的小尺度的高频扰动。非绝热加热垂直廓线对模式模拟MJO有重要的影响,而非绝热加热廓线很大程度上取决于所使用的积云参数化方案。模式水平分辨率的变化不会对加热廓线的结构产生明显的影响,而垂直分辨率的变化会对加热廓线的垂直结构产生一定的调制作用,进而对模拟的MJO起到调制作用。 相似文献
11.
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
12.
Typhoon Usagi (1319) was simulated by using the Advanced Weather Research and Forecasting numerical model (WRF) with different horizontal resolution to understand the impact of horizontal resolution on the intensity and characteristics of typhoon’s microstructures (including dynamic and microphysical structure). The simulated results show that the improvement of horizontal resolution from 5 km to 1 km has little impact on the track which is comparable to real results, but has a significant impact on the intensity and microstructures, and especially, the impact on wind speed at 10 m height, the vertical movement and precipitation intensity is the greatest. When the resolution is increased to 1 km, the intensity and characteristics of typhoon’s microstructures can be simulated better. In lower resolution simulations, some structural characteristics, including more asymmetrical and more outward tilted eyewall, and less water vapor flux on sea surface, work together to weaken typhoon intensity. 相似文献
13.
Dependence of Hurricane Intensity and Structures on Vertical Resolution and Time-Step Size 总被引：5，自引：0，他引：5
In view of the growing interests in the explicit modeling of clouds and precipitation, the effects of varying vertical resolution and time-step sizes on the 72-h explicit simulation of Hurricane Andrew (1992) are studied using the Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model (i.e., MM5) with the finest grid size of 6 km. It is shown that changing vertical resolution and time-step size has significant effects on hurricane intensity and inner-core cloud/precipitation, but little impact on the hurricane track. In general, increasing vertical resolution tends to produce a deeper storm with lower central pressure and stronger three-dimensional winds, and more precipitation. Similar effects, but to a less extent, occur when the time-step size is reduced. It is found that increasing the low-level vertical resolution is more efficient in intensifying a hurricane, whereas changing the upper-level vertical resolution has little impact on the hurricane intensity. Moreover, the use of a thicker surface layer tends to produce higher maximum surface winds. It is concluded that the use of higher vertical resolution,a thin surface layer, and smaller time-step sizes, along with higher horizontal resolution, is desirable to model more realistically the intensity and inner-core structures and evolution of tropical storms as well as the other convectively driven weather systems. 相似文献
14.
The numerical simulation of typhoons has been found to be very sensitive to the vertical resolution of the model. During the updating of the TRAMS model from version 1.0 to 3.0, the horizontal resolution has been increased from 36 km to 9 km, while the vertical layer number only increased from 55 to 65 layers. The lack of high vertical resolution limits the performance of the TRAMS model in typhoon forecasting to a certain extent. In order to study the potential improvement of typhoon forecasting by increasing the vertical resolution, this paper increases the vertical resolution of the TRAMS model from 65 to 125 layers for the first time for a comparative simulation test. The results of the case study with Typhoon Hato (2017) show that the model with high vertical resolution can significantly enhance the warm structure caused by water vapor flux convergence and vertical transport, thus accurately simulating the rapid strengthening process of the typhoon. Meanwhile, the model with 125-layer vertical resolution can simulate the asymmetric structural characteristics of the wind field, which are closer to the observations and can help to reduce the bias in typhoon track forecasting. The improvement of vertical resolution is also trialed by using the batch test results of several landfalling typhoons in 2016-2017. The experimental results show that the typhoon forecast of the model becomes consistent with the observations only when the number of vertical layers of the model increases to about 125 layers, which in turn causes a large computational burden. In the next step, we will try to solve the computational burden problem caused by ultra-high vertical resolution with the top boundary nesting technique, and realize the application of high vertical resolution in the actual operation of the TRAMS model. 相似文献
15.
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
16.
We set four sets of simulation experiments to explore the impacts of horizontal resolution (HR) and vertical resolution (VR) on the microphysical structure and boundary layer fluxes of tropical cyclone (TC) Hato (2017). The study shows that higher HR tends to strengthen TC. Increasing VR in the upper layers tends to weaken TC, while increasing VR in the lower layers tends to strengthen TC. Simulated amounts of all hydrometeors were larger with higher HR. Increasing VR at the upper level enhanced the mixing ratios of cloud ice and cloud snow, while increasing VR at the lower level elevated the mixing ratios of graupel and rainwater. HR has greater impact on the distributions of hydrometeors. Higher HR has a more complete ring structure of the eyewall and more concentrated hydrometeors along the cloud wall. Increasing VR at the lower level has little impact on the distribution of TC hydrometeors, while increasing VR at the upper level enhances the cloud thickness of the eyewall area. Surface latent heat flux (SLHF) is influenced greatly by resolution. Higher HR leads to larger water vapor fluxes and larger latent heat, which would result in a stronger TC. A large amount of false latent heat was generated when HR was too high, leading to an extremely strong TC, VR has a smaller impact on SLHF than HR. But increasing VR at the upper-level reduces the SLHF and weakens TC, and elevating VR at the lower-level increases the SLHF and strengthens TC. The changes in surface water vapor flux and SLHF were practically identical and the simulation results were improved when HR and VR were more coordinated. The friction velocity was greater with higher VR.
Enhancing VR at the lower level increased the friction velocity, while increasing VR at the upper level reduced it. 相似文献
17.
热带气旋(TC)的结构(含形态)与强度及其变化关系密切,著名的Dvorak定强技术即为TC形态(水平)变化与强度关系的生动描述,近年来水平尺度与强度变化的关系也渐受关注。然而,至今未涉及整体形态(即体积)与TC强度变化的关系。利用欧洲中期数值预报中心(ECMWF)0.25 °的ERA-Interim再分析资料,统计并初步分析了2006—2015年西北太平洋TC的外围水平尺度和“体积”的特征及其与强度的可能关系:水平尺度与TC强度的相关性总体较弱;而TC“体积”与强度的相关性更显著,且TC“体积”随强度增强而增大的关系适用于所有强度级别;此外,TC垂直尺度(正涡度区伸展高度)与强度也有一定的正相关,且在TC较弱时(台风强度以下)更显著。伴随较弱TC增强的主要是垂直尺度的增大,当TC达到台风强度后,与TC强度继续增强相伴随的主要是水平尺度的增大。TC“体积”能较好地综合表征水平尺度和垂直尺度与TC强度变化的关系,借助TC“体积”对TC强度预报有一定的参考价值。 相似文献
18.
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