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热带大气对流耦合波动的小波分析 被引量:3
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作者 曹杰 温之平 +1 位作者 常有礼 李湘瑞 《中国科学:地球科学》 CSCD 北大核心 2012年第4期577-586,共10页
利用NOAA逐日向外长波辐射(OLR)资料和小波分析方法对热带大气中主要对流耦合波动的时空分布特征进行了研究.结果表明,小波分析能有效地辨析出1992年热带大气对流耦合MJO、Kelvin波、ER波、TD波、WMRG波和EMRG波及其活动特征.其中,MJO... 利用NOAA逐日向外长波辐射(OLR)资料和小波分析方法对热带大气中主要对流耦合波动的时空分布特征进行了研究.结果表明,小波分析能有效地辨析出1992年热带大气对流耦合MJO、Kelvin波、ER波、TD波、WMRG波和EMRG波及其活动特征.其中,MJO和ER波的传播速度最慢,Kelvin波和TD波次之,MRG波最快;印度洋至西太平洋的MJO和TD波、日界线附近的Kelvin波、西太平洋附近的ER波、日界线附近以东的MRG波振幅最大;在北半球冬春季的MJO、春夏季的Kelvin波、秋季的ER波、夏季的TD波活跃;WMRG波在北半球秋季比较活跃;EMRG波则全年均会出现.这些时空分布特征很好地与有关理论研究结果相吻合,时频域中的小波分析是另一种揭示热带对流耦合波动演变规律的有效方法. 展开更多
关键词 热带大气 对流耦合波 分析 复最小二乘法
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MJO Simulations by GAMIL1.0 and GAMIL2.0 被引量:1
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作者 XIE Xin WANG Bin +1 位作者 LI Li-Juan DONG Li 《Atmospheric and Oceanic Science Letters》 2012年第1期49-54,共6页
GAMIL2.0 is the newly released version of the Grid-point Atmospheric Model of IAP LASG(GAMIL),in which the major modifications from GAMIL1.0 include an updated deep convection scheme and the incorporation of a two-mom... GAMIL2.0 is the newly released version of the Grid-point Atmospheric Model of IAP LASG(GAMIL),in which the major modifications from GAMIL1.0 include an updated deep convection scheme and the incorporation of a two-moment bulk stratiform cloud microphysics scheme.This study evaluates the performances of both versions on Madden Julian Oscillation(MJO) simulations.The results show that GAMIL2.0 obtains an enhanced MJO eastward and northward propagation,which is weak in GAMIL1.0,and it reproduces a more reasonable MJO major structure coupling upper level wind,lower level wind,and outgoing long wave radiation.The contributions of each scheme and factor to the improvement of GAMIL2.0 simulations need further study. 展开更多
关键词 MJO GAMIL evaluation
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Wavelet analysis of the convectively-coupled equatorial waves 被引量:1
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作者 CAO Jie WEN ZhiPing +1 位作者 CHANG YouLi LI XiangRui 《Science China Earth Sciences》 SCIE EI CAS 2012年第4期675-684,共10页
The spatial and temporal distribution characteristics of the main convectively-coupled equatorial waves were analyzed with the OLR data provided by NOAA and the method of wavelet analysis.The results indicate that the... The spatial and temporal distribution characteristics of the main convectively-coupled equatorial waves were analyzed with the OLR data provided by NOAA and the method of wavelet analysis.The results indicate that the wavelet analysis can effectively distinguish MJO,Kelvin,ER,TD,and EMRG wave and the characteristics of their activities in 1992.The propagation speeds of MJO and ER wave are the slowest,following by Kelvin and TD wave and with MRG the fastest.The MJO from the Indian Ocean to the West Pacific Ocean,the Kelvin wave near the International Date Line,the ER and the TD wave around the West Pacific Ocean and the MRG in the eastern of the International Date Line have the biggest wave amplitude.The MJO in boreal winter and spring,the Kelvin wave in boreal spring and summer,the ER wave in boreal autumn,and the TD wave in boreal summer are active.The WMRG wave activates in boreal autumn,whereas EMRG wave appears year-round.These spatial and temporal characteristics agree well with the results of relevant theoretical studies,indicating that the wavelet analysis in the time-frequency domain is another effective method to reveal the evolution of convectively-coupled equatorial waves. 展开更多
关键词 equatorial atmosphere convectively-coupled wave wavelet analysis complex least square method
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Aerodynamic performance of the flexibility of corrugated dragonfly wings in flapping flight
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作者 Yuping Wang Xinyi He +3 位作者 Guoyi He Qi Wang Longsheng Chen Xiaochen Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2022年第11期48-56,共9页
At low Reynolds numbers,the variable flexibility of flapping insect wings is considered essential in improving the favorable aerodynamic forces.To further explore whether significant aerodynamic coupling exists betwee... At low Reynolds numbers,the variable flexibility of flapping insect wings is considered essential in improving the favorable aerodynamic forces.To further explore whether significant aerodynamic coupling exists between the microstructure and passive flexible deformation,this paper proposes three technical comparison airfoils:a corrugated wing with deformation,a symmetric flat plate wing with deformation,and a corrugated wing without deformation.Based on STAR-CCM+software,this paper numerically solves the Navier-Stokes equations using the fluid-structure interaction method.The results show that the aerodynamic performance of the flexible corrugated wing is better than that of the rigid corrugated wing,and its lift and thrust are both improved to a certain extent,and the thrust efficiency of the flexible corrugated wing is significantly higher than that of the flexible flat plate.Although the thrust is improved,a part of the lift is lost,and as the flapping amplitude increases past 35°,the disparity gradually increases.A comparison of the flexible technical airfoils shows that the corrugated structure promotes thrust and retards lift,which is closely related to the formation and dissipation of strong vortex rings during the downstroke phase.On the premise of maintaining typical flapping without falling,dragonflies can fly with skillful efficiency by adjusting the way they flap their wings.The results of this work provide new insight into the formation and role of thrust in flapping maneuvering flight and provide a specific reference for developing new bionic flapping-wing aircraft. 展开更多
关键词 Flexibility corrugated wing Fluid-structure interaction Unsteady aerodynamics Forward flight
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