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1.
The impacts of AMSU-A and IASI (Infrared Atmospheric Sounding Interferometer) radiances assimila-tion on the prediction of typhoons Vicente and Saola (2012) are studied by using the ensemble transform ...  相似文献   

2.
The impact of assimilating radiances from the Advanced Microwave Sounding Unit-A (AMSU-A) on the track prediction of Typhoon Megi (2010) was studied using the Weather Research and Forecasting (WRF) model and a hybrid ensemble three-dimensional variational (En3DVAR) data assimilation (DA) system. The influences of tuning the length scale and variance scale factors related to the static background error covariance (BEC) on the track forecast of the typhoon were studied. The results show that, in typhoon radiance data assimilation, a moderate length scale factor improves the prediction of the typhoon track. The assimilation of AMSU-A radiances using 3DVAR had a slight positive impact on track forecasts, even when the static BEC was carefully tuned to optimize its performance. When the hybrid DA was employed, the track forecast was significantly improved, especially for the sharp northward turn after crossing the Philippines, with the flow-dependent ensemble covariance. The flow-dependent BEC can be estimated by the hybrid DA and was capable of adjusting the position of the typhoon systematically. The impacts of the typhoon-specific BEC derived from ensemble forecasts were revealed by comparing the analysis increments and forecasts generated by the hybrid DA and 3DVAR. Additionally, for 24 h forecasts, the hybrid DA experiment with use of the full flow-dependent background error substantially outperformed 3DVAR in terms of the horizontal winds and temperature in the lower and mid-troposphere and for moisture at all levels.  相似文献   

3.
基于WRF中尺度模式,采用集合卡尔曼滤波方法同化中国岸基多普勒天气雷达径向速度资料,对2015年登陆台风彩虹(1522)进行数值试验。从台风强度、路径、结构等方面验证了同化效果,并对不同区域雷达观测资料的同化敏感性进行讨论。试验结果表明:在同化窗内同化分析场台风位置误差相比未同化平均减小15 km,最多时刻减小38 km,同化资料时次越多,确定性预报路径误差越小。同化雷达资料后较好地反映出台风彩虹(1522)近海加强过程,台风中心最低气压同化分析和预报误差相比未同化最大减小超过25 hPa,台风眼的尺度、眼墙处对流非对称结构相比未同化与观测更加接近。试验还表明:台风内核100 km范围内的雷达观测对同化效果影响最大,仅同化这部分资料(约占总量的20%)各方面效果与同化全部资料相近,而仅同化100 km以外资料效果明显不及同化所有资料。仅同化台风内核雷达观测资料可以在不影响同化效果的前提下,使集合同化计算机时减小为原来的1/3,该策略可为台风实际业务预报提供一定参考。  相似文献   

4.
杨春  闵锦忠  刘志权 《大气科学》2017,41(2):372-384
在WRFDA-3DVar(Weather Research and Forecasting model's 3-dimensional variational data assimilation)的框架下,添加了新的探测器AMSR2(Advanced Microwave Scanning Radiometer 2)微波辐射率资料的同化模块,实现了AMSR2辐射率资料在中小尺度同化系统中的有效使用。台风"山神"(Son-Tinh)直接同化AMSR2资料的个例试验结果表明,AMSR2资料可以很好的探测出台风的形态,并且与没有同化该资料的控制试验相比,同化AMSR2辐射率资料可以有效提高模式分析场的质量,进一步提高了台风中心气压,最大风速和台风路径的预报。  相似文献   

5.
基于集合卡尔曼变换与三维变分(ETKF-3DVAR)混合资料同化系统和欧洲中期天气预报中心(ECWMF)的全球集合预报,以"梅花"台风为例,分析了台风系统预报误差的流依赖特征,讨论了耦合系数在混合同化和预报中的敏感性及其对预报质量的影响。结果显示,台风系统的预报误差协方差具有显著的中小尺度结构特征,集合估计的预报误差协方差结构能够再现其流依赖属性。相对于3DVAR方案,混合资料同化方案的最优耦合系数对台风系统的分析和预报质量具有更好的改善;但不同的耦合系数对台风路径预报有明显的影响,不合适的耦合系数甚至可能导致更坏的结果,只有耦合了相对合适的预报误差协方差的流依赖信息,混合资料同化方案才可能对分析和预报质量有正效果。这表明在混合资料同化系统中,构造一种具有自适应能力的耦合权重函数,实现相对最优权重的自动选择,对充分发挥混合资料同化方案的潜在优势具有重要意义。  相似文献   

6.
2018年第14号台风“摩羯”对山东造成了大范围暴雨和大风天气,基于WRF(Weather Research and Forecasting)模式及其Hybrid-3DVAR混合同化预报系统,对Hybrid-3DVAR不同集合协方差比例和不同航空气象数据转发(aircraft meteorological data relay,以下简称AMDAR)资料同化时间窗对台风“摩羯”预报的影响进行了数值研究。结果表明:加大集合协方差比例对台风“摩羯”路径预报有较大影响和改进;当全部取来自集合体的流依赖误差协方差时,预报的台风路径最好,降水预报也最接近实况;AMDAR资料同化对于台风路径和降水预报也有正的改进作用,但加大集合协方差比例到100%时对台风路径预报影响更大;不同资料同化时间窗会影响同化的AMDAR资料数量,从而影响台风降水精细化预报;45 min同化时间窗的要素预报误差最小,对台风造成的强降水精细特征预报最接近实况;不同资料同化时间窗主要影响台风降水预报落区分布,对台风路径预报影响相对较小。  相似文献   

7.
2019年超级台风“利奇马”对我国东部地区造成了巨大灾害,针对台风“利奇马”,研究GPS ZTD资料同化对于台风“利奇马”登陆后降水预报的影响。在进行GPS ZTD资料同化试验前,采取了稳定性检查、极值检查、双权重检查、偏差订正检查等质量控制方法以改善资料的同化应用水平。模拟试验结果表明在同化探空、风廓线等常规资料基础上,增加质控GPS ZTD有效改善了初始场的水汽条件,使得低层水汽辐合更强,从而改进了台风外围雨带的预报。并且通过循环同化能够改善初始环流场,进而改进了台风路径的预报使得台风主体降水的位置得到改善。  相似文献   

8.
李新峰  赵坤  王明筠  明杰 《气象科学》2013,33(3):255-263
高分辨率的中尺度预报模式ARPS及其3DVAR/云分析系统,针对2010年登陆福建的超强台风“鲇鱼”,研究对流可分辨尺度下,每1h循环同化沿海新一代多普勒雷达网资料分析、研究对台风初始场和预报场的改进作用.结果表明:单独同化雷达资料可显著改善初始场中的台风内核区动力和热力结构,以及台风强度和位置,进而提高18h台风强度、路径和降水预报,但预报路径和降水分布与实况仍存在差异.在雷达资料同化基础上加入常规观测资料,对初始场中台风内核区结构改进不大.但在显著调整大尺度背景场,从而进一步减少台风路径预报误差,能准确预报出福建沿海两个强降水区域的位置和强度.总体而言,雷达资料同化主要提高台风结构分析,而常规观测资料同化主要改善环境场分析,两者有效结合使得预报结果和实况最为接近.  相似文献   

9.
In this paper, the three-dimensional variational data assimilation scheme (3DVAR) in the mesoscalemod el version 5 (MM5) of the US Pennsylvania State University/National Center for Atmospheric Research is used to study the effect of assimilating the sea-wind data from QuikSCAT on the prediction of typhoon track and intensity. The case of Typhoon Dujuan (2003) is first tested and the results show appreciable improvements. Twelve other cases in 2003 are then evaluated. The assimilation of the QuikSCAT data produces significant impacts on the structure of Dujuan in terms of the horizontal and vertical winds, sealevel pressure and temperature at the initial time. With the assimilation, the 24-h (48-h) track prediction of 11 (10) out of the 12 typhoons is improved. The 24-h (48-h) prediction of typhoon intensity is also improved in 10 (9) of the 12 cases. These experiments therefore demonstrate that assimilation of the QuikSCAT sea-wind data can increase the accuracy of typhoon track and intensity predictions through modification of the initial fields associated with the typhoon.  相似文献   

10.
The THORPEX-Pacific Asian Regional Campaign 2008 (T-PARC 2008) was performed during the period of August 1 through October 4, 2008, and mainly focused on the genesis, intensification, recurvature, and extra-tropical transition over the western North Pacific in collaboration with TCS-08 and DOTSTAR. This study investigates the impact of dropsonde observations on the improvement of predictive skills for Typhoon Sinlaku (0813) and Jangmi (0815) during T-PARC 2008. Twelve and six cases were selected for Sinlaku and Jangmi, respectively. The dropsonde data were assimilated by the Weather Research and Forecasting (WRF)-Three-Dimensional Variational system (3DVAR), and then the typhoon track was obtained by running a WRF model for up to 72 hours. Consequently, the assimilation of the dropsonde data had positive impacts on the typhoon track forecast and lead to mean track error reductions of 22.5% and 17.0% for Typhoon Sinlaku and Jangmi, respectively. Subsequent experiments were also conducted to determine the sensitivities of storm activity in the horizontal and vertical distributions and the dynamic and thermodynamic variables using the dropsonde data. The results show that sondes released south of storms around the middle troposphere (500~850 hPa) are more effective in improving the track forecast. The dynamic variables mainly affect the storm tracks, while the thermodynamic variables mainly affect the central pressure of the storm.  相似文献   

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