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1.
采用中尺度数值模式WRFv3.5对2014年超强台风“威马逊”进行数值模拟。利用雷达、卫星、自动站逐时降水资料,对比单参数WSM6云方案和双参数WDM6云方案在模拟台风路径、强度、降水分布及水成物含量上的差异,分析雨滴粒子的谱型特征及微物理源、汇项对云中雨水含量的影响。与上海台风研究所的最佳路径数据对比显示,两方案均较好地模拟出了台风“威马逊”的移动路径,WDM6方案的整体路径误差更小;模拟的强度差异则较为显著,WDM6方案的海平面最低气压值偏高,强度偏弱。两方案模拟的累积降雨分布虽与自动站实测资料基本一致,但WDM6方案模拟的强降水概率偏高,弱降水概率偏低。两方案模拟的对流区雪、霰、雨水含量均大于TRMM卫星反演结果,且WDM6方案的对流云较多,总体雨水含量偏高;两方案均模拟出了雷达回波分布的整体特征,但眼区尺度偏大,WDM6方案在融化层以下缺少眼墙之外的弱回波区且大于39 dBz的强回波区偏多,同样显示了雨水含量（或尺度）偏大。由于WDM6方案为暖雨（云、雨水）双参数模式,对云滴活化、云雨转换及云、雨谱型有一定的改进,其能较合理地模拟出雨滴谱随台风发展的演变特征;模拟显示,云、雨滴的收集碰并及固态粒子的融化是雨水的主要源项,WDM6方案增加了云雨水自动转化率及雨水碰并云水率,导致该方案的空中雨水含量偏高,且随高度的降低快速减小;此外,由于WDM6方案使用简单的寇拉公式进行云滴活化,初始云凝结核数的变化即可造成雪、霰、云雨水含量的改变,故建议在具体大气气溶胶条件下,对方案中的云滴生成参数化过程做相应的调整。 相似文献
2.
The impact of different cloud microphysics parameterization schemes on the intensity and structure of the
Super-strong Typhoon Rammasun (1409) in 2014 is investigated using the Weather Research and Forecasting model
version 3.4 with eight cloud microphysics parameterization schemes. Results indicate that the uncertainty of cloud
microphysics schemes results in typhoon forecast uncertainties, which increase with forecast time. Typhoon forecast
uncertainty primarily affects intensity predictions, with significant differences in predicted typhoon intensity using the
various cloud microphysics schemes. Typhoon forecast uncertainty also affects the predicted typhoon structure.
Greater typhoon intensity is accompanied by smaller vortex width, tighter vortex structure, stronger wind in the
middle and lower troposphere, greater height of the strong wind region, smaller thickness of the eyewall and the
outward extension of the eyewall, and a warmer warm core at upper levels of the eye. The differences among the
various cloud microphysics schemes lead to the different amounts and distributions of water vapor and hydrometeors
in clouds. Different hydrometeors have different vertical distributions. In the radial direction, the maxima for the
various hydrometeors forecast by a single cloud microphysics scheme are collocated with each other and with the
center of maximum precipitation. When the hydrometeor concentration is high and hydrometeors exist at lower
altitudes, more precipitation often occurs. Both the vertical and horizontal winds are the strongest at the location of
maximum precipitation. Results also indicate that typhoon intensities forecast by cloud microphysics schemes
containing graupel processes are noticeably greater than those forecast by schemes without graupel processes. Among
the eight cloud microphysics schemes investigated, typhoon intensity forecasts using the WRF Single-Moment 6-class
and Thompson schemes are the most accurate. 相似文献
3.
基于WRF(Weather Research and Forecasting)模式及其3Dvar(3-Dimentional Variational)资料同化系统,采用36、12、4 km嵌套网格进行快速更新循环同化和不同的微物理及积云对流参数化方案对比试验,对2011年5月8日鲁中一次局地大暴雨过程进行了研究。结果表明,快速更新循环同化地面观测资料是影响模式降水落区预报准确性的关键因素,不同的微物理和积云对流参数化方案主要影响降水强度预报。采用不同的微物理参数化方案和积云对流参数化方案进行降水预报对比试验表明,LIN方案和WSM6(WRF Single-Moment 6-class)微物理参数化方案对降水预报均较好,LIN方案降水预报较WSM6方案略强。4 km网格预报使用K-F (Kain-Fritsch)积云对流参数化方案或不使用积云对流参数化方案,预报的降水均较好。4 km网格使用旧的K-F积云对流参数化方案,预报的近地层大气风场偏弱,导致大气动力抬升作用偏弱,从而造成模式降水预报偏弱。 相似文献
4.
变性再发展热带气旋Yaji(2006)的数值模拟研究 总被引：2，自引：2，他引：0
利用中尺度模式WRF对2006年14号热带气旋Yaji的变性过程进行了双重嵌套模拟。结果表明,采用高分辨率的TRMM/TMI卫星反演SST资料,在第一重区域(网格距为15km)采用WSM3微物理方案和Betts-Miller对流参数化方案,在第二重移动嵌套区域(网格距为5km)采用Lin微物理方案,不采用对流参数化方案,模式能较好地模拟Yaji的路径和变性前后的强度演变,其中模拟的路径平均误差为64km,强度平均误差为2.5hPa,模拟的风场分布与Quickscat卫星反演的风场分布也较为吻合。利用模拟资料还研究了Yaji变性过程中的非对称流特征。 相似文献
5.
以三个西北太平洋热带气旋（TC）为例,利用WRF（Weather Research and Forecasting）模式进行了一系列海表温度（SST）敏感性数值试验,揭示了西北太平洋SST增暖对TC的强度、尺度及潜在破坏力的影响及其机理。结果表明,在距TC中心100 km以内区域的SST升高有利于TC强度增加,但会减小TC内核尺度;而在距TC中心100 km以外的SST升高并不会使TC强度明显增加甚至使TC强度减弱,但同时会增加TC内核尺度。伴随着低层向眼墙的入流,升高的外区SST会使TC区表层的大气温度和湿度升高,造成眼墙附近海气温差和湿度差及向内的气压梯度力减小,进而减少进入TC眼墙内的感热和潜热,不利于TC增强,但有利于眼墙向外移动,使TC内核尺度增加。内区SST升高与外区SST升高对TC强度及尺度变化的作用机理相反。因此,当TC移过冷或暖洋面时,TC的强度和尺度的变化不仅取决于局地洋面的冷或暖状况,还取决于TC内区和外区SST的差异。由于TC内区和外区SST对TC强度和内核尺度的不同作用,可能存在一个临界范围,当暖池范围在这个临界范围之内时TC潜在破坏力随暖池范围的扩大而增大,但当暖池范围超过这个临界范围时TC潜在破坏力便不会随着暖池范围的继续扩大而增大,甚至会有所减小。 相似文献
6.
Typhoon Rananim (2004) was one of the severest typhoons landfalling the Chinese mainland
from 1996 to 2004. It brought serious damage and induced prodigious economical loss. Using a new
generation of mesoscale model, named the Weather Research and Forecasting (WRF) modeling system,
with 1.667 km grid horizontal spacing on the finest nested mesh, Rananim was successfully simulated
in terms of track, intensity, eye, eyewall, and spiral rainbands. We compared the structures of
Rananim to those of hurricanes in previous studies and observations to assess the validity of
simulation. The three-dimensional (3D) dynamic and thermal structures of eye and eyewall were
studied based on the simulated results. The focus was investigation of the characteristics of
the vortex Rossby waves in the inner-core region. We found that the Rossby vortex waves propagate
azimuthally upwind against the azimuthal mean tangential flow around the eyewall, and their
period was longer than that of an air parcel moving within the azimuthal mean tangential flow.
They also propagated outward against the boundary layer inflow of the azimuthal mean vortex.
Futhermore, we studied the connection between the spiral potential vorticity (PV) bands and
spiral rainbands, and found that the vortex Rossby waves played an important role in the
formation process of spiral rainbands. 相似文献
7.
The influence of outer-core surface entropy fluxes （SEFs） on tropical cyclone （TC） outer rainband activity is investigated in this study with a fully compressible,nonhydrostatic model.A control simulation and two sensitivity experiments with the outer-core SEF artificially increased and decreased by 20% respectively were conducted to examine the quasi-periodic outer rainband behavior.Larger negative horizontal advection due to the greater radial wind and the positive contribution by asymmetric eddies leads to a longer period of outer-rainband activity in the SEF-enhanced experiment.The well-developed outer rainbands in the control and SEF-reduced simulations significantly limit the TC intensity,whereas such an intensity suppression influence is not pronounced in the SEF-enhanced experiment.As diabatic heating in outer rainbands strengthens the outer-core tangential wind,the quasi-periodic activity of outer rainbands contributes to the quasi-periodic variations of the inner-core size of the TCs. 相似文献
8.
本文以GFS资料为初始场,利用WRF（v3.6.1）模式对2015年第22号台风“彩虹”进行了数值研究。采用CMA（中国气象局）台风最佳路径、MTSAT卫星、自动站降水为观测资料,对比了4个微物理方案（Lin、WSM6、GCE和Morrison）对“彩虹”台风路径、强度、结构、降水的模拟性能。模拟发现上述4个云微物理方案都能较好地模拟出“彩虹”台风西行登陆过程,但是其模拟的台风强度、结构及降水存在较大差异;就水成物而言,除GCE方案对雨水的模拟偏高以外,其他方案对云水、雨水过程的模拟较为接近,其差异主要存在于云冰、雪、霰粒子的模拟上。本文对比分析了WSM6和Morrison两个方案模拟的云微物理过程,发现WSM6方案模拟的雪和霰粒子融化过程显著强于Morrison方案,但是冰相粒子间转化过程的强度明显弱于Morrison方案。云微物理过程的热量收支分析表明:WSM6方案模拟的眼区潜热更强,暖心结构更为显著,台风中心气压更低。细致的云微物理转化分析表明,此次台风降水的主要云微物理过程是水汽凝结成云水和凝华为云冰;生成的云水一方面被雨水收集碰并直接转化为雨水,另一方面先被雪粒子碰并收集转化为霰,然后霰粒子融化成雨水;而生成的云冰则通过碰并增长转化为雪。小部分雪粒子通过碰并收集过冷水滴并淞附增长为霰粒子,随后融化为雨水,大部分雪粒子则直接融化形成地面降水。 相似文献
9.
The basic structure and cloud features of Typhoon Nida
(2016) are simulated using a new microphysics scheme (Liuma)
within the Weather Research and Forecasting (WRF) model. Typhoon
characteristics simulated with the Liuma microphysics scheme are
compared with observations and those simulated with a commonly-
used microphysics scheme (WSM6). Results show that using
different microphysics schemes does not significantly alter the
track of the typhoon but does significantly affect the intensity
and the cloud structure of the typhoon. Results also show that
the vertical distribution of cloud hydrometeors and the
horizontal distribution of peripheral rainband are affected by
the microphysics scheme. The mixing ratios of rain water and
graupel correlate highly with the vertical velocity component
and equivalent potential temperature at the typhoon eye-wall
region. According to the simulation with WSM 6 scheme, it is
likely that the very low typhoon central pressure results from
the positive feedback between hydrometeors and typhoon
intensity. As the ice-phase hydrometeors are mostly graupel in
the Liuma microphysics scheme, further improvement in this
aspect is required. 相似文献
10.
Numerical simulations of heavy rainfall over central Korea on 21 September 2010 using the WRF model 总被引：1，自引：0，他引：1
On 21 September 2010, heavy rainfall with a local maximum of 259 mm d-1occurred near Seoul, South Korea. We examined the ability of the Weather Research and Forecasting(WRF) model in reproducing this disastrous rainfall event and identified the role of two physical processes: planetary boundary layer(PBL) and microphysics(MPS) processes. The WRF model was forced by 6-hourly National Centers for Environmental Prediction(NCEP) Final analysis(FNL) data for 36 hours form 1200 UTC 20 to 0000 UTC 22 September 2010. Twenty-five experiments were performed, consisting of five different PBL schemes—Yonsei University(YSU), Mellor-Yamada-Janjic(MYJ), Quasi Normal Scale Elimination(QNSE),Bougeault and Lacarrere(Bou Lac), and University of Washington(UW)—and five different MPS schemes—WRF SingleMoment 6-class(WSM6), Goddard, Thompson, Milbrandt 2-moments, and Morrison 2-moments. As expected, there was a specific combination of MPS and PBL schemes that showed good skill in forecasting the precipitation. However, there was no specific PBL or MPS scheme that outperformed the others in all aspects. The experiments with the UW PBL or Thompson MPS scheme showed a relatively small amount of precipitation. Analyses form the sensitivity experiments confirmed that the spatial distribution of the simulated precipitation was dominated by the PBL processes, whereas the MPS processes determined the amount of rainfall. It was also found that the temporal evolution of the precipitation was influenced more by the PBL processes than by the MPS processes. 相似文献
11.
WRF-WSM3微物理方案在青藏高原地区暴雪模拟中的改进及试验 总被引：1，自引：0，他引：1
通过青藏高原一次暴雪过程的模拟试验,对WRF模式中的WSM3微物理方案中的降水模拟偏差原因进行了分析,并根据观测试验结果,提出了改进WSM3微物理方案中冰核浓度的2种计算方案。通过调整温度和冰核浓度之间的关系,检验了冰核浓度Pigen过程对降水的影响。结果显示,WSM3方案对青藏高原地区的冰核浓度估计过高;当考虑了冰面过饱和度随温度区间的变化后,计算的冰核浓度可以改进降水的模拟效果;但通过温度的变化和冰面过饱和度二者的调整,降水模拟的效果并不明显。冰核浓度对温度变化的敏感存在着一个范围,冰面过饱和度和温度区间的大小存在一定关系。通过另外2个个例和敏感性试验的研究结果表明,对于温度较高的固态降水,冰核浓度的变化对降水模拟的改进不显著。 相似文献
12.
0920号超强台风“卢碧”引起的强海上大气波导成因分析与数值模拟研究 总被引：2，自引：1，他引：1
基于中国台湾地区主持的侵台台风之飞机侦察及下投式探空仪观测实验（Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region,DOTSTAR）获得的高分辨率下投式探空仪探测资料,分析了2003年9月—2012年8月所有发生在中国台湾地区附近海域的台风型大气波导事件,遴选出一次由0920号超强台风“卢碧”引起的强台风型海上大气波导过程作为研究对象。利用欧洲中期数值预报中心（ECMWF）再分析资料（水平分辨率0.125°×0.125°）,对此次波导的生成原因进行了分析;基于WRF模式比较了不同初始化方法对台风强度、尺度和周围台风型大气波导的模拟能力。结果表明,此次强台风型大气波导发生在台风环流西北侧外围的弱下沉运动区,其形成与850 hPa高度附近北方强干空气平流导致湿度随高度锐减密切相关。在数值模拟中运用台风动力初始化方法,可以有效改进台风强度、路径和尺度的模拟效果,进而有利于改善台风型大气波导尤其是波导层所在高度的模拟效果。台风外围出现的大气波导通常以悬空波导为主,模拟效果与台风螺旋雨带和内核尺度的模拟关系密切,而与台风强度和眼墙结构关系不大。中尺度数值模式WRF具有模拟台风型大气波导的能力,是研究台风型大气波导的有力手段。 相似文献
13.
用WRF模式中不同云微物理参数化方案对华南一次暴雨过程的数值模拟和性能分析 总被引：10，自引：3，他引：7
本文使用中尺度数值模式WRFV3.4中的8种不同云微物理过程参数化方案,模拟2010年5月6～7日华南一次暴雨事件,探讨不同云微物理方案对华南暴雨模拟的影响。结果表明:不同云微物理方案对不同量级降水模拟效果总体较好。WSM3方案对小到大雨和大暴雨的模拟效果最好,对暴雨的模拟最差;WDM5方案对暴雨模拟效果最好。结合TS评分和误差分析结果,整体效果最好的是WSM5方案,最差的是Lin方案。对于同一云微物理参数化方案,不同分辨率的降水模拟结果差异不大,但同一分辨率的不同云微物理参数化方案的降水结果差异较大,这说明云微物理过程比模式分辨率对暴雨模拟的影响更大。 相似文献
14.
云物理过程是云和降水形成的重要环节。本文针对2011年6月23日发生在北京地区的一次大暴雨过程进行了云降水与天气特征分析,并开展了WRF模式中10种不同云微物理方案对此次暴雨强度、落区和发生时间的敏感性数值模拟试验。研究结果表明,此次大暴雨是由多单体组织、合并形成深厚的中尺度对流系统,并具有明显的短时局地特征和有利的高低空、高低纬度大中尺度天气环流形势及强烈的水汽输送条件。暴雨强度、落区和发生时间的数值模拟结果对云物理方案非常敏感。不同云物理方案对累积降水量≥50 mm和≥100 mm的暴雨模拟的ETS评分显示,只有Thompson方案对此暴雨量级的评分均为正,其他方案的ETS评分均不理想,特别是对累积降水量≥100 mm的大暴雨模拟。在小时暴雨强度和发生时间方面,Thompson方案模拟效果也较好,其次是Lin方案和WSM6方案;对区域累积最大降水量和落区的模拟方面,Thompson方案和Morrison方案模拟的最大累积降水量更接近观测值,但在落区方面,一些具有完整云物理过程的单参数方案（Lin方案、WSM6方案）模拟效果较好,但模拟的最大降水量偏小。针对暖雨的双参数方案WDM6对区域平均降水模拟较好,但对暴雨极端降水模拟较差。对造成差异的原因分析表明,不同云物理方案的差异主要体现在雪和霰的参数化方面,由于采用的粒子谱分布、密度和末速度不同,导致云中粒子间的碰并和形成过程不同,大部分云物理方案模拟的霰含量高,雪含量低。这种云微物理过程的差异会导致云动力过程的反馈作用出现明显不同,但这种反馈作用的差异主要体现在降水粒子对上升气流的拖曳作用不同。尽管云中相变潜热过程对云动力过程具有很重要的影响,但不同云物理方案在相变潜热过程和温度廓线分布方面造成的差异并不明显。因此,云物理方案中考虑合理的粒子谱分布、形态和密度变化,有利于提高暴雨的模拟效果。 相似文献
15.
Cloud-to-ground （CG） lightning data,storm intensity and track data,and the data from a Doppler radar and the Tropical Rainfall Measuring Mission （TRMM） satellite,are used to analyze the temporal and spatial characteristics of lightning activity in Typhoon Molave （0906） during different periods of its landfall （pre-landfall,landfall,and post-landfall）.Parameters retrieved from the radar and the satellite are used to compare precipitation structures of the inner and outer rainbands of the typhoon,and to investigate possible causes of the different lightning characteristics.The results indicate that lightning activity was stronger in the outer rainbands than in the eyewall and inner rainbands.Lightning mainly occurred to the left （rather than ＂right＂ as in previous studies of US cases） of the moving typhoon,indicating a significant spatial asymmetry.The maximum lightning frequency in the tropical cyclone （TC） eyewall region was ahead of that in the whole TC region,and the outbreaks of eyewall lightning might indicate deepening of the cyclone.Stronger lightning in the outer rainbands is found to be associated with stronger updraft,higher concentrations of rain droplets and large ice particles at elevated mixed-phase levels,and the higher and broader convective clouds in the outer rainbands.Due to the contribution of large cloud nuclei,lightning intensity in the outer rainbands has a strong positive correlation with radar reflectivity.The ratio of positive CG lightning in the outer rainbands reached its maximum 1 h prior to occurrence of the maximum typhoon intensity at 2000 Beijing Time （BT） 18 July 2009.During the pre-landfall period （0300 BT 18 July-0050 BT 19 July）,the typhoon gradually weakened,but strong lightning still appeared.After the typhoon made landfall at 0050 BT 19 July,CG lightning density rapidly decreased,but the ratio of positive lightning increased.Notably,after the landfall of the outer rainbands at 2325 BT 18 July （approximately 1.5 h prior to the landfall of the TC）,significantly higher ice particle density derived from the TRMM data was observed in the outer rainbands,which,together with strengthened convection resulted from the local surface roughness effect,might have caused the enhanced lightning in the outer rainbands around the landfall of Molave. 相似文献
16.
The impacts of dry air on tropical cyclone (TC) development at different latitudes with no mean flows are investigated with idealized simulations. It is found that the effective radius of the dry air is sensitive to its vertical distribution and the background earth rotation. The effect of low-level dry-air layer in inhibiting TC development decreases with increasing latitude. At lower latitudes, the greater boundary layer gradient wind imbalance results in a strong low-level inflow, and the dry air can easily penetrate into the TC inner-core region. The intruding dry air inhibits the inner-core deep convection and leads to marked asymmetric convective structure, which significantly suppresses TC development. In contrast, at higher latitudes, the dry air gets moistened before reaching the TC inner-core region due to a weaker radial inflow but can suppress the development of the outer spiral rainbands. The suppressed outer spiral rainbands lead to a weaker barrier effect to the boundary layer inflow and help TC development. Furthermore, the lower the altitude of dry-air layer resides, the greater the impact on TC intensification. The low-level pathway associated with the boundary layer inflow plays an important role on how dry-air layer acts on a TC without considering the mean flow effects. Through examining the climatological distribution of the moisture field, we expect that the intrusion of dry air can be more frequent in the North Atlantic area and therefore has more effects on TC development than in the western North Pacific. 相似文献
17.
In this study, the dependence of tropical cyclone (TC) development on the inner-core structure of the parent vortex is examined using a pair of idealized numerical simulations. It is found that the radial profile of inner-core relative vorticity may have a great impact on its subsequent development. For a system with a larger inner-core relative vorticity/inertial stability, the conversion ratio of the diabatic heating to kinetic energy is greater. Furthermore, the behavior of the convective vorticity eddies is likely modulated by the system-scale circulation. For a parent vortex with a relatively higher inner-core vorticity and larger negative radial vorticity gradient, convective eddy formation and radially inward propagation is promoted through vorticity segregation. This provides a greater potential for these small-scale convective cells to self-organize into a mesoscale inner-core structure in the TC. In turn, convectively induced diabatic heating that is close to the center, along with higher inertial stability, efficiently enhances system-scale secondary circulation. This study provides a solid basis for further research into how the initial structure of a TC influences storm dynamics and thermodynamics. 相似文献
18.
Impacts of the Lowest Model Level Height on Tropical Cyclone Intensity and Structure简 总被引：1，自引：0，他引：1
Variable thicknesses in the lowest half-ηmodel level （LML） are often used in atmospheric models to compute surface diagnostic fields such as surface latent and sensible heat fluxes.The effects of the LML on simulated tropical cyclone （TC）evolution were investigated in this study using the Weather Research and Forecasting （WRF） model.The results demonstrated notable influences of the LML on TC evolution when the LML was placed below 12 m.The TC intensification rate decreased progressively with a lowering of the LML,but its ultimate intensity change was relatively small.The maximum 10-m winds showed different behavior to minimum sea level pressure and azimuthally-averaged tangential winds,and thus the windpressure relationship was changed accordingly by varying the LML.The TC circulation was more contracted in association with a higher LML.Surface latent heat fluxes were enhanced greatly by elevating the LML,wherein the wind speed at the LML played a dominant role.The changes in the wind speed at the LML were dependent not only on their profile differences,but also the different heights they were taken from.Due to the enhanced surface heat fluxes,more intense latent heat release occurred in the eyewall,which boosted the storm＇s intensification.A higher LML tended to produce a stronger storm,and therefore the surface friction was reinforced,which in turn induced stronger boundary layer inflow together with increased diabatic heating. 相似文献
19.
利用WRF模式中三种云微物理参数化方案(Lin、Eta和WSM6)对青藏高原一次强降水过程进行模拟试验,将模拟降水结果与实测资料进行对比,以评估不同云微物理参数化方案对该区域降水过程的模拟性能。结果表明:三种方案均能够模拟出此次降水天气过程的发生,但在主要降水区域和降水强度两方面仍与实测资料存在偏差;在水凝物方面,三种方案对冰粒子的模拟较接近,Lin和WSM6方案模拟的雪粒子差异较大,但霰粒子无明显差异。进一步对比分析了Lin和WSM6方案模拟的云微物理转化过程,结果表明:这两种方案都表现出了霰向雨水转化的特点。在Lin方案中,通过水汽向霰粒子凝华、霰碰并水汽凝华生成的雪粒子以及霰碰并云水这三种过程生成的霰粒子最终融化为雨水。而在WSM6方案中,一方面水汽凝结成云水,云水被雪和霰粒子碰并收集转化为霰,之后霰融化为雨水;另一方面水汽凝华为冰粒子,一部分冰转化为雪,雪直接融化为雨水或转化为霰融化为雨水,另一部分冰转化为霰,霰融化为雨水。 相似文献
20.
Impact of Cloud Microphysical Processes on the Simulation of Typhoon Rananim near Shore. Part II: Typhoon Intensity and Track 
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下载免费PDF全文 The impact of cloud microphysical processes on the simulated intensity and track of Typhoon Rananim is discussed and analyzed
in the second part of this study. The results indicate that when the cooling effect due to evaporation of rain water is excluded,
the simulated 36-h maximum surface wind speed of Typhoon Rananim is about 7 m s−1 greater than that from all other experiments; however, the typhoon landfall location has the biggest bias of about 150 km
against the control experiment. The simulated strong outer rainbands and the vertical shear of the environmental flow are
unfavorable for the deepening and maintenance of the typhoon and result in its intensity loss near the landfall. It is the
cloud microphysical processes that strengthen and create the outer spiral rainbands, which then increase the local convergence
away from the typhoon center and prevent more moisture and energy transport to the inner core of the typhoon. The developed
outer rainbands are supposed to bring dry and cold air mass from the middle troposphere to the planetary boundary layer (PBL).
The other branch of the cold airflow comes from the evaporation of rain water itself in the PBL while the droplets are falling.
Thus, the cut-off of the warm and moist air to the inner core and the invasion of cold and dry air to the eyewall region are
expected to bring about the intensity reduction of the modeled typhoon. Therefore, the deepening and maintenance of Typhoon
Rananim during its landing are better simulated through the reduction of these two kinds of model errors. 相似文献