谱松弛同化技术对台风路径及强度模拟的影响
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摘要
采用WRF模式针对2016年第17号台风"鲇鱼"设计了多组对比试验及敏感性试验,考察谱松弛同化技术对台风路径及强度模拟的影响。通过其与格点松弛方法的对比发现:这两种方法都能显著改善台风路径和强度的模拟,由于谱松弛方法仅部分同化高层的大尺度场,允许模式更好的发展自身的中小尺度信息,其模拟的台风强度较格点松弛试验模拟的台风强度更接近观测。对影响谱松弛方法的关键参数松弛波数及系数进行的敏感性试验表明:台风模拟对谱松弛波数及系数的选择均很敏感。适当增加波数可以改善台风路径及强度的模拟,但并非波数越多越好,波数超过一定阈值会导致模拟的台风强度明显偏弱;适当增大系数同样能改善台风路径和强度的模拟,但并非越大越好,需根据模式设置优化选取。本研究表明:选取谱松弛波数为5,系数为0.000 3~0.003时,台风模拟有显著改进。
Multiple group contrast tests and sensitivity tests for the 17 th Typhoon"Megi"in 2016 are designed using the WRF model to study the influence of spectral nudging assimilation technique on typhoon track and intensity simulation. By contrasting the influence of spectral nudging with grid nudging on Typhoon simulation,it turns out that: both of the two methods can significantly improve the simulation of track and intensity of typhoon. Spectral nudging method only partially assimilate large scale field of high-level, permitting model to develop better small scale information on its own, though the simulated typhoon intensity of spectral nudging is closer to observation than of grid nudging. The results from sensitivity tests of spectral nudging parameters,nudging wave number and coefficient showing that Typhoon simulation is sensitive to wave number and coefficient. Proper increase of wave number can improve the simulation of typhoon track and intensity, but not the larger the better. The wave number over a certain threshold will cause the typhoon intensity to be weaker.Appropriately increasing the coefficient can also improve typhoon simulation, but not the larger the better. It is necessary to choose the best according to the mode setting. This study shows that selecting spectral nudging wave number as 5, and the coefficient as 0.0003~0.003, improves the typhoon simulation greatly.
Multiple group contrast tests and sensitivity tests for the 17 th Typhoon"Megi"in 2016 are designed using the WRF model to study the influence of spectral nudging assimilation technique on typhoon track and intensity simulation. By contrasting the influence of spectral nudging with grid nudging on Typhoon simulation,it turns out that: both of the two methods can significantly improve the simulation of track and intensity of typhoon. Spectral nudging method only partially assimilate large scale field of high-level, permitting model to develop better small scale information on its own, though the simulated typhoon intensity of spectral nudging is closer to observation than of grid nudging. The results from sensitivity tests of spectral nudging parameters,nudging wave number and coefficient showing that Typhoon simulation is sensitive to wave number and coefficient. Proper increase of wave number can improve the simulation of typhoon track and intensity, but not the larger the better. The wave number over a certain threshold will cause the typhoon intensity to be weaker.Appropriately increasing the coefficient can also improve typhoon simulation, but not the larger the better. It is necessary to choose the best according to the mode setting. This study shows that selecting spectral nudging wave number as 5, and the coefficient as 0.0003~0.003, improves the typhoon simulation greatly.
引文
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[15]曾先锋,周天军.谱逼近方法对区域气候模式性能的改进:不同权重函数的影响[J].气象学报,2012,70(5):1084-1097.
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[22]杨凯,施宗强,马治国,等.2016年台风“鲇鱼”对福建省农业生产影响调查评估[C]//第34届中国气象学会年会S12提升气象科技水平,保障农业减灾增效论文集.北京:中国气象学会,2017.
[2]许映龙,张玲,高拴柱.我国台风预报业务的现状及思考[J].气象,2010,36(7):43-49.
[3]王喜年.风暴潮灾害及其预报与防御对策[J].海洋预报,1998,15(3):26-31.
[4]端义宏,陈联寿,许映龙,等.我国台风监测预报预警体系的现状及建议[J].中国工程科学,2012,14(9):4-9.
[5]Choi S J,Lee D K.Impact of spectral nudging on the downscaling of tropical cyclones in regional climate simulations[J].Advances in Atmospheric Sciences,2016,33(6):730-742.
[6]Giorgi F,Marinucci M R,Bates G T.Development of a secondgeneration regional climate model(Reg CM2).Part I:boundarylayer and radiative transfer processes[J].Monthly Weather Review,1993,121(10):2794-2813.
[7]Davies H C.A laterul boundary formulation for multi-level prediction models[J].Quarterly Journal of the Royal Meteorological Society,1976,102(432):405-418.
[8]魏和林,符淙斌,王维强.区域气候模式侧边界的处理对东亚夏季风降水模拟的影响[J].大气科学,1998,22(5):779-790.
[9]赵宗慈,罗勇.区域气候模式在东亚地区的应用研究——垂直分辨率与侧边界对夏季季风降水影响研究[J].大气科学,1999,23(5):522-532.
[10]Stauffer D R,Seaman N L,Binkowski F S.Use of four-dim ensional data assimilation in a limited-area mesoscale model part II:effects of data assimilation within the planetary boundary layer[J].Monthly Weather Review,1991,119(3):734-754.
[11]Waldron K M,Paegle J,Horel J D.Sensitivity of a spectrally filtered and nudged limited-area model to outer model options[J].Monthly Weather Review,1996,124(3):529-547.
[12]Von Storch H,Langenberg H,Feser F.A spectral nudging technique for dynamical downscaling purposes[J].Monthly Weather Review,2000,128(10):3664-3673.
[13]王淑莉,徐祥德,康红文,等.应用谱逼近方法模拟2008年初南方持续性降水过程及其水汽通道周期特征分析[J].大气科学,2016,40(3):476-488.
[14]Wang H,Wang Y Q,Xu H M.Improving simulation of a tropical cyclone using dynamical initialization and large-scale spectral nudging:a case study of typhoon megi(2010)[J].Acta Meteorologica Sinica,2013,27(4):455-475.
[15]曾先锋,周天军.谱逼近方法对区域气候模式性能的改进:不同权重函数的影响[J].气象学报,2012,70(5):1084-1097.
[16]Liu P,Tsimpidi A P,Hu Y,et al.Differences between downscaling with spectral and grid nudging using WRF[J].Atmospheric Chemistry and Physics Discussions,2012,12(8):1191-1213.
[17]Cha D H,Jin C S,Lee D K,et al.Impact of intermittent spectral nudging on regional climate simulation using weather research and forecasting model[J].Journal of Geophysical Research Atmospheres,2011,116(D10):D10103.
[18]Skamarock W C,Klemp J B,Dudhia J,et al.A description of the advanced research WRF version 2[R].NCAR Technical Note NCAR/TN-468+STR,2005:7-25.
[19]Ying M,Zhang W,Yu H,et al.An overview of the china meteorological administration tropical cyclone database[J].Journal of Atmospheric and Oceanic Technology,2014,31(2):287-301.
[20]Neumann C S,Pelissier J M.An analysis of atlantic tropical cyclone forecast errors,1970-1979[J].Monthly Weather Review,1981,109(6):1248-1266.
[21]Powell M D,Aberson S D.Accuracy of united states tropical cyclone landfall forecasts in the atlantic basin(1976-2000)[J].Bulletin of the American Meteorological Society,2001,82(12):2749-2768.
[22]杨凯,施宗强,马治国,等.2016年台风“鲇鱼”对福建省农业生产影响调查评估[C]//第34届中国气象学会年会S12提升气象科技水平,保障农业减灾增效论文集.北京:中国气象学会,2017.