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1.
国家气象中心台风路径数值预报模式自1996年6月投入业务运行以来, 一直在背景场中采用经验平滑滤波技术消除浅台风和嵌入轴对称的台风bogus涡旋技术。但事实上, 在采用经验平滑技术消除背景场中弱的位置不准确的浅台风涡旋同时, 也滤除了台风中心周围一些宝贵的非对称气流结构, 同时, 由于实际的台风涡旋结构是非对称的, 因而对采用轴对称涡旋的模式初始场而言, 或多或少的贡献了一些模式预报结果的路径误差。为了调查这部分非对称结构对台风预报路径误差的影响, 从T213L31全球谱模式提供的背景场中抽取浅台风周围的非对称流场, 将之加入到轴对称的台风bogus涡旋中。初步的个例试验发现, 加入非对称流场后, 能有效地减少台风路径预报误差。 相似文献
2.
Based on high-resolution reanalysis data of the European Centre for Medium-Range Weather Forecasts, several samples of tropical cyclones (TCs), including tropical storms, severe tropical storms, and typhoons, in the South China Sea (SCS), were selected for composite analysis. The structures of these three types of vortices and their differences with ‘bogus’ vortices were investigated. Results showed that TCs in the SCS have characteristics that are distinctly different from vortices formed by the bogussing scheme used at Guangzhou Institute of Tropical and Marine Meteorology, such as no anticyclone in higher layers, strong convergence concentrated at the bottom of the troposphere, and strong divergence happening in higher layers instead of at 400 hPa. These differences provide clues for constructing a more realistic structure for TCs in the SCS. It was also found that the three types of vortices have some structural features in common. The area with high wind speed is fan-shaped in the north around the TC center, the maximum vorticity appears at 925 hPa, the strongest convergence appears at 1000 hPa, and strong divergence is located from 150 to 100 hPa. On the contrary, significant differences between them were revealed. The warm cores in tropical storms, severe tropical storms, and typhoons are located at 600–400 hPa, 400−300 hPa, and 400−250 hPa, respectively. Among the three types of TCs, the bogus vortex of tropical storms has the largest errors in structure and suffers the largest errors in track forecasts. However, typhoons have the largest errors in the forecast of intensity. This may be related to the great impacts of ocean on TC intensity. 相似文献
3.
应用1999—2003年中国中央气象台 (CMO)、日本气象厅 (JMA) 以及美国联合台风警报中心 (JTWC) 发布的西北太平洋热带气旋综合预报资料, 从总误差、逐年误差趋势、不同海区误差、不同路径趋势误差、不同强度趋势误差等5个方面对各预报中心的路径及强度预报结果进行分析, 结果表明:5年总的平均误差以JTWC的路径预报误差最小, 而JMA的强度预报较准确; 在不同海域, 各预报中心的路径预报能力各有优势, 但在热带气旋的强度预报方面, JMA的方法在各海区都较稳定; 对不同路径趋势热带气旋的预报方面, 除了南海转向热带气旋的路径预报比JMA和CMO稍差一些之外, JTWC的路径预报在大多数情况下都是好于或相当于JMA和CMO; 在不同强度变化趋势热带气旋的预报方面, JTWC在大多数情况下都优于其他中心。上述结果帮助业务和科技人员全面了解各预报中心的预报能力优劣, 也为今后改进我国的热带气旋预报提供有益的参考。 相似文献
4.
ＡＢｏｇｕｓＴｙｐｈｏｏｎＳｃｈｅｍｅａｎｄＩｔｓＡｐｐｌｉｃａｔｉｏｎｔｏａＭｏｖａｂｌｅＮｅｓｔｅｄＭｅｓｈＭｏｄｅｌＷａｎｇＧｕｏｍｉｎ（王国民）（ＤｅｐａｒｔｍｅｎｔｏｆＡｔｍｏｓｐｈｅｒｉｃＳｃｉｅｎｃｅｓ，ＮａｍｉｎｇＵｎｉｖｅｒｓｉｔｙ... 相似文献
5.
非静力模式预报热带气旋路径个例试验 总被引：3，自引：0，他引：3
利用非静力模式（ＭＭ５Ｖ２）对９６１１号、９９０４号等北上热带气旋路径预报进行民试验。用松驰（Ｎｕｄｇｉｎｇ）四维同化方案和人造热带气旋（Ｂｏｇｕｓ ＴＣ）技术,使独ｔ－１２时刻的模式场（包括第一个Ｂｏｇｕｓ ＴＣ）通过预积分逐步逼近ｔｏ时刻的Ｂｏｇｕｓ ＴＣ和同时刻的观测资料场庆１９９９年能够得到相隔６ｈ一次的ＡＴ１０６Ｌ１９预报场后,分别在ｔ－１２、ｔ－ａ６和ｔｏ时刻各制做一个Ｂｏｇｕｓ ＴＣ 相似文献
6.
Super Typhoon Mangkhut (2018) was the most high-impact typhoon in 2018 because of its long lifespan and significant intensity. The operational track forecasts in the short-to-medium range (deterministic and probabilistic forecast) showed a great uncertainty and the forecast landing points varied with different lead times. This study applied ensembles of high-resolution ECMWF forecasts to investigate the major factors and mechanisms of the bias production of the Mangkhut forecast track. The ensembles with the largest track bias were analyzed to examine the possible bias associated factors. The results suggested that environmental steering flows were the main cause for the erroneous southward track error with a variance contribution of 72%. The tropical cyclone (TC) size difference and the interaction of the TC with the subtropical high (SH) were other two key factors that contributed to the track error. Particularly, larger TCs may have led to a stronger erosion of the southern part of the SH, and thus induced significant changes in the large-scale environment and eventually resulted in an additional northward movement of TC.
相似文献7.
1. IntroductionStudies on the tracks of tropical cyclones (TCs)have been one of the core problems in TC dynamics.In earlier researches, TCs are often viewed aspoint vortices, Rankine vortices. For example, Yeh(1950) and Kuo (1969), adopting dynamical methods,studied the motions of TCs and the effects of environ-ments. Their findings indicated that the motion tracksof TCs are characterized by cyclonic trochoidal oscil-lations.Syono (1955), by solving the barotropic vorticityequation, obta… 相似文献
8.
应用国家气象中心全球谱模式T213L31(简称T213) 及其升级版本T639L60(简称T639) 对2009—2010年西北太平洋热带气旋数值预报的结果进行对比。结果表明:T213与T639模式24～120 h预报平均距离误差基本相近,但由于T639模式分辨率较高,T639模式的热带气旋强度预报明显好于T213模式。从分类误差来看,T639模式对于西北行登陆及转向热带气旋的路径预报好于T213模式,但对西行及北上热带气旋预报误差偏大。对于异常路径热带气旋预报,T639模式能较好预报环流形势的突然调整,对路径突变的热带气旋预报比T213模式有明显优势;从登陆类热带气旋预报的移向误差来看,T213模式存在东北偏北向系统性偏差,T639模式存在东北偏东向系统性偏差。 相似文献
9.
Super Typhoon Mangkhut(2018)was the most high-impact typhoon in 2018 because of its long lifespan and significant intensity.The operational track forecasts in the short-to-medium range(deterministic and probabilistic forecast)showed a great uncertainty and the forecast landing points varied with different lead times.This study applied ensembles of high-resolution ECMWF forecasts to investigate the major factors and mechanisms of the bias production of the Mangkhut forecast track.The ensembles with the largest track bias were analyzed to examine the possible bias associated factors.The results suggested that environmental steering flows were the main cause for the erroneous southward track error with a variance contribution of 72%.The tropical cyclone(TC)size difference and the interaction of the TC with the subtropical high(SH)were other two key factors that contributed to the track error.Particularly,larger TCs may have led to a stronger erosion of the southern part of the SH,and thus induced significant changes in the large-scale environment and eventually resulted in an additional northward movement of TC. 相似文献
10.
全球数值模式中的台风初始化Ⅰ:方案设计 总被引：2，自引：0，他引：2
由于缺少大量有效的观测资料,台风初始化对数值天气预报业务模式而言,仍然是一个悬而末决的难题.中国国家气象中心自从1996年将台风数值预报系统投入业务运行以来,一直使用经验的人造bogus涡旋台风初始化技术.实际上,不同时期的台风有着不同的环流结构,即使同一个台风在不同的生命期也具有不同的结构特征,而这些结构特征的差异并不能依靠现有的bogus涡旋技术体现出来,这种主观方法的统一性与台风在时空上的差异性形成了强烈的反差.最近,基于国家气象中心全球资料分析同化-预报循环系统,设计和发展了一套新的台风初始化业务方案,它主要由初始涡旋形成、涡旋重定位和涡旋调整3部分过程组成.相比于业务中使用的人造bogus涡旋台风初始化方案,新方案在很大程度上减少了人为因素对台风涡旋结构的影响,而更多地是依靠数值模式自身的动力和物理过程来协调约束产生三维空间的涡旋结构.应用新方案,文中对生成于西北太平洋的2006年0605号台风格美(Kaemi)进行了数值试验,初步分析表明,新方案在实现台风涡旋环流结构的初始化方面效果较好,同时,对台风格美多个时次的预报结果也显示,相比于业务使用的bogus方案而言,新方案对台风路径平均预报误差有了大幅度的降低. 相似文献
11.
Initial mesoscale vortex effects on the tropical cyclone(TC) motion in a system where three components coexist(i.e.,an environmental vortex(EV),a TC,and mesoscale vortices) were examined using a barotropic vorticity equation model with initial fields where mesoscale vortices were generated stochastically.Results of these simulations indicate that the deflection of the TC track derived from the initial mesoscale vortices was clearly smaller than that from the beta effect in 60% of the cases.However,they may have a more significant impact on the TC track under the following circumstances.First,the interaction between an adjacent mesoscale vortex and the TC causes the emergence of a complicated structure with two centers in the TC inner region.This configuration may last for 8 h,and the two centers undergo a cyclonic rotation to make the change in direction of the TC motion.Second,two mesoscale vortices located in the EV circulation may merge,and the merged vortex shifts into the EV inner region,intensifying both the EV and steering flow for the TC,increasing speed of the TC. 相似文献
12.
On the bogussing of tropical cyclones in numerical models: A comparison of vortex profiles 总被引：5，自引：0，他引：5
Summary At the resolutions currently in use, and with the sparse oceanic data coverage, numerical analyses cannot adequately represent tropical cyclone circulations for use in numerical weather prediction models. In many cases there is no circulation present at all. Most numerical weather prediction centers therefore employ a bogussing scheme to force a tropical cyclone vortex into the numerical analysis. The standard procedure is to define a synthetic data distribution based on an analytically prescribed vortex, which is passed to the analysis scheme as a set of high quality observations.In this study, four commonly used bogus vortices are examined by comparing resultant forecast tracks in an environment at rest, and in a background flow that simulates a typical monsoon trough-subtropical ridge structure. There are three main findings, each of which has significance for operational tropical cyclone track prediction. First, great care is needed in the choice of the characteristics of the bogus vortex, such as the radius and magnitude of the maximum wind. Second, the tropical cyclone trajectories can be very sensitive to their initial position in the idealised environment. Third, the bogus vortex can substantially influence the environment, especially over longer time periods and for vortices of larger size.With 9 Figures 相似文献
13.
利用TOVS资料分析了2000年几个热带气旋的结构,发现与经典概念模型所描述的结构有一定的差异,主要表现在:(1)在水平结构上,非对称结构呈多样性,高度场的低层低值中心(或高层高值中心)与温度场的高值中心并不一定重合;(2)在垂直结构上,高度场的低层低值距平与高层高值距平的配置也呈多样性,特别是存在上、下层距平中心倾斜,或高层只是处于高压区的边缘,不存在明显的高值距平中心与热带气旋相对应.还参照TOVS中的热带气旋结构,进行了修订热带气旋数值预报模式系统中人造台风模型(台风BOGUS)结构的研究,发现修订后的台风BOGUS 能够更好地与环境场协调,并且能对热带气旋的路径预报取得较好的效果.这一方面说明了台风BOGUS的结构对其路径预报有较大的影响,另一方面也说明利用TOVS资料中的热带气旋结构能改善热带气旋路径预报.这也为台风BOGUS的修订和发展提供了依据. 相似文献
14.
采用MTSAT2卫星红外云图资料及NCEP/NCAR再分析资料,研究了热带气旋Meranti(2010)异常路径的成因。结果表明:Meranti的路径由西行、打转、北上三个阶段组成。在西行、北上阶段,环境场引导流起着主要作用,Meranti的非对称结构对其也有一定影响,非对称对流系统的作用较弱。在打转阶段,环境场引导流和非对称结构均不能解释Meranti打转的原因,而非对称对流系统则起着主要作用。不同阶段的Meranti外缘线的分形维数特征存在明显区别。在西行、北上阶段,其分形维数处于高值段且变化平缓;在打转阶段,则处于低值段且变化较大。 相似文献
15.
全球数值模式中的台风初始化Ⅱ: 业务应用 总被引：2，自引：0，他引：2
由于缺少大量有效的观测资料,台风初始化对数值天气预报业务模式而言,仍然是一个悬而末决的难题.中国国家气象中心自从1996年将台风数值预报系统投入业务运行以来,一直使用经验的人造bogus涡旋台风初始化技术.实际上,不同时期的台风有着不同的环流结构,即使同一个台风在不同的生命期也具有不同的结构特征,而这些结构特征的差异并不能依靠现有的bogus涡旋技术体现出来,这种主观方法的统一性与台风在时空上的差异性形成了强烈的反差.最近,基于国家气象中心全球资料分析同化-预报循环系统,设计和发展了一套新的台风初始化业务方案,它主要由初始涡旋形成、涡旋重定位和涡旋调整3部分过程组成.相比于业务中使用的人造bogus涡旋台风初始化方案,新方案在很大程度上减少了人为因素对台风涡旋结构的影响,而更多地是依靠数值模式自身的动力和物理过程来协调约束产生三维空间的涡旋结构.应用新方案,文中对生成于西北太平洋的2006年0605号台风格美(Kaemi)进行了数值试验,初步分析表明,新方案在实现台风涡旋环流结构的初始化方面效果较好,同时,对台风格美多个时次的预报结果也显示,相比于业务使用的bogus方案而言,新方案对台风路径平均预报误差有了大幅度的降低. 相似文献
16.
A technique for estimating tropical cyclone (TC) intensity over the Western North
Pacific utilizing FY-3 Microwave Imager (MWRI) data is developed. As a first step, we
investigated the relationship between the FY-3 MWRI brightness temperature (TB) parameters,
which are computed in concentric circles or annuli of different radius in different MWRI
frequencies, and the TC maximum wind speed (Vmax) from the TC best track data. We found that
the parameters of lower frequency channels’ minimum TB, mean TB and ratio of pixels over the
threshold TB with a radius of 1.0 or 1.5 degrees from the center give higher correlation. Then
by applying principal components analysis (PCA) and multiple regression method, we established
an estimation model and evaluated it using independent verification data, with the RMSE being
13 kt. The estimated Vmax is always stronger in the early stages of development, but slightly
weaker toward the mature stage, and a reversal of positive and negative bias takes place with
a boundary of around 70 kt. For the TC that has a larger error, we found that they are often
with less organized and asymmetric cloud pattern, so the classification of TC cloud pattern
will help improve the acuracy of the estimated TC intensity, and with the increase of
statistical samples the accuracy of the estimated TC intensity will also be improved. 相似文献
17.
利用中尺度数值模式设计一组高分辨率理想试验,采用位涡趋势方法定量诊断分析热带气旋在登陆我国华东沿海地形时,其运动发生的精细化变化以及不同因子的贡献。结果表明,平地的存在使得登陆热带气旋移速相对更快,当华东沿海地形存在时,热带气旋移速显著增大,这种增速现象主要是由于平地和地形所引起的非对称气流以及相应的引导气流变化所致,这很可能是导致预报路径误差的一个重要原因。平地试验中,陆地在热带气旋低层激发出中小尺度的非对称气流,与之不同的是,实际地形的加入激发出更大尺度并且更强的非对称偏南气流。位涡趋势方法的诊断结果表明,非引导效应总体而言对热带气旋运动贡献较小,这是因为这些因子相互抵消,但在不同的垂直层次上,不同的非引导因子贡献存在明显的差异。 相似文献
18.
Hyeong-Bin Cheong In-Hyuk Kwon Hyun-Gyu Kang Ja-Rin Park Hyun-Jun Han Jae-Jin Kim 《Asia-Pacific Journal of Atmospheric Sciences》2011,47(3):293-303
A new Tropical Cyclone (TC) initialization method with the structure adjustable bogus vortex was applied to the forecasts of track, central pressure, and wind intensity for the 417 TCs observed in the Western North Pacific during the 3-year period of 2005–2007. In the simulations the Final Analyses (FNL) with 1° × 1° resolution of National Center for Environmental Prediction (NCEP) were incorporated as initial conditions. The present method was shown to produce improved forecasts over those without the TC initialization and those made by Regional Specialized Meteorological Center Tokyo. The average track (central pressure, wind intensity) errors were as small as 78.0 km (11.4 hPa, 4.9 m s?1) and 139.9 km (12.4 hPa, 5.5 m s?1) for 24-h and 48-h forecasts, respectively. It was found that the forecast errors are almost independent on the size and intensity of the observed TCs because the size and intensity of the bogus vortex can be adjusted to fit the best track data. The results of this study indicate that a bogus method is useful in predicting simultaneously the track, central pressure, and intensity with accuracy using a dynamical forecast model. 相似文献
19.
This study explored the impact of coastal radar observability on the forecast of the track and rainfall of Typhoon Morakot(2009)using a WRF-based ensemble Kalman filter(EnKF)data assimilation(DA)system.The results showed that the performance of radar EnKF DA was quite sensitive to the number of radars being assimilated and the DA timing relative to the landfall of the tropical cyclone(TC).It was found that assimilating radial velocity(Vr)data from all the four operational radars during the 6 h immediately before TC landfall was quite important for the track and rainfall forecasts after the TC made landfall.The TC track forecast error could be decreased by about 43% and the 24-h rainfall forecast skill could be almost tripled.Assimilating Vr data from a single radar outperformed the experiment without DA, though with less improvement compared to the multiple-radar DA experiment.Different forecast performances were obtained by assimilating different radars, which was closely related to the first-time wind analysis increment, the location of moisture transport, the quasi-stationary rainband, and the local convergence line.However, only assimilating Vr data when the TC was farther away from making landfall might worsen TC track and rainfall forecasts.Besides, this work also demonstrated that Vr data from multiple radars, instead of a single radar, should be used for verification to obtain a more reliable assessment of the EnKF performance. 相似文献
20.
Large-scale atmospheric information plays an important role in the regional model for the forecasts of weather such as tropical cyclone (TC). However, it is difficult to be fully represented in regional models due to domain size and a lack of observation data, particularly at sea used in regional data assimilation. Blending analysis has been developed and implemented in regional models to reintroduce large-scale information from global model to regional analysis. Research of the impact of this large-scale blending scheme for the Global / Regional Assimilation and PrEdiction System (CMA-MESO) regional model on TC forecasting is limited and this study attempts to further progress by examining the adaptivity of the blending scheme using the two-dimensional Discrete Cosine Transform (2D-DCT) filter on the model forecast of Typhoon Haima over Shenzhen, China in 2016 and considering various cut-off wavelengths. Results showed that the error of the 24-hour typhoon track forecast can be reduced to less than 25 km by applying the scale-dependent blending scheme, indicating that the blending analysis is effectively able to minimise the large-scale bias for the initial fields. The improvement of the wind forecast is more evident for u-wind component according to the reduced root mean square errors (RMSEs) by comparing the experiments with and without blending analysis. Furthermore, the higher equitable threat score (ETS) provided implications that the precipitation prediction skills were increased in the 24h forecast by improving the representation of the large-scale feature in the CMA-MESO analysis. Furthermore, significant differences of the track error forecast were found by applying the blending analysis with different cut-off wavelengths from 400 km to 1200 km and the track error can be reduced less than by 10 km with 400 km cut-off wavelength in the first 6h forecast. It highlighted that the blending scheme with dynamic cut-off wavelengths adapted to the development of different TC systems is necessary in order to optimally introduce and ingest the large-scale information from global model to the regional model for improving the TC forecast. In this paper, the methods and data applied in this study will be firstly introduced, before discussion of the results regarding the performance of the blending analysis and its impacts on the wind and precipitation forecast correspondingly, followed by the discussion of the effects of different blending scheme on TC forecasts and the conclusion section. 相似文献