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沈新勇, 刘佳, 秦南南, 冯琎. 台风麦莎登陆后粘性摩擦对正压特征波动的影响[J]. 大气科学, 2013, 37(6): 1219-1234. DOI: 10.3878/j.issn.1006-9895.2013.12047
引用本文: 沈新勇, 刘佳, 秦南南, 冯琎. 台风麦莎登陆后粘性摩擦对正压特征波动的影响[J]. 大气科学, 2013, 37(6): 1219-1234. DOI: 10.3878/j.issn.1006-9895.2013.12047
SHEN Xinyong, LIU Jia, QIN Nannan, FENG Jin. Impact of Viscous Friction on Barotropic Eigenvalue Wave of Typhoon Matsa after Its Landing[J]. Chinese Journal of Atmospheric Sciences, 2013, 37(6): 1219-1234. DOI: 10.3878/j.issn.1006-9895.2013.12047
Citation: SHEN Xinyong, LIU Jia, QIN Nannan, FENG Jin. Impact of Viscous Friction on Barotropic Eigenvalue Wave of Typhoon Matsa after Its Landing[J]. Chinese Journal of Atmospheric Sciences, 2013, 37(6): 1219-1234. DOI: 10.3878/j.issn.1006-9895.2013.12047

台风麦莎登陆后粘性摩擦对正压特征波动的影响

Impact of Viscous Friction on Barotropic Eigenvalue Wave of Typhoon Matsa after Its Landing

  • 摘要: 本文推导出柱坐标系下含有粘性摩擦项的正压方程组。选取2005年台风麦莎登陆浙江过程中的8月6日15时的WRF(Weather Research and Forecasting)模式输出资料,利用数值差分方法对该正压方程组求特征波解,分析粘性摩擦对台风麦莎内部正压特征波动的影响。结果表明,重力惯性外波在粘性摩擦的影响下,最不稳定波的波数为45左右,波动在摩擦的影响下衰减,波动沿逆时针传播,在半径1000 km处,1波波速为47.43 m/s,在半径r>800 km的范围内,径向风分量扰动加大,辐合辐散运动增强;而摩擦影响下的涡旋Rossby波,2波最不稳定,波动增长率减小,在半径r=200 km处波动相速度为4.282~29.172 m/s,扰动涡度大值区范围减小,涡旋Rossby波的波动区域沿着径向向台风中心收缩。分析包含所有波动时,考虑摩擦后,最不稳定波数在45左右且波动衰减,1波波速在r=1000 km处(外螺旋雨带)为26.374 m/s;在半径r=200 km(内螺旋雨带)为5.275 m/s,考虑径向基本气流后,最不稳定波的波数保持不变,半径r=1000 km处的波速增加为30.324 m/s,r=200 km(内螺旋雨带)处波速为6.065 m/s,摩擦使得径向风分量扰动明显增大,辐合辐散运动加强。

     

    Abstract: In this study, barotropic equations including a friction term are derived in cylindrical coordinates. The numerical differential method is applied to the barotropic equations to construct the characteristic wave solutions. The data from a Weather Research and Forecasting model simulation of typhoon Matsa at 1500 LST on August 6, 2005 are then used to calculate the barotropic characteristic wave structures to study how they are affected by friction inside typhoon Matsa. The results show that the wavenumber is 45 for most unstable external inertia-gravity waves, which are weakened by friction. The waves propagate counterclockwise, and the wave speed for wavenumber 1 at a radius of 1000 km is 47.43 m/s. Perturbed radial winds increase and convergence strengthens at radii greater than 800 km. The wavenumber is 2 for most unstable vortex Rossby waves, whose growth rate is reduced by friction. The wave speed is 4.282-29.172 m/s at a radius of 200 km; the area of large perturbed vorticity decreases, and the area of the vortex Rossby waves shrinks toward the typhoon's center. When all the waves are considered, friction weakens the waves at wavenumber 45. The wave speed of wavenumber 1 is 26.374 m/s at a radius of 1000 km, whereas it is 5.275 m/s at a radius of 200 km. The wave speed of wavenumber 1 becomes 30.324 m/s at a radius of 1000 km and 6.065 m/s at a radius of 200 km when the radial wind is considered. The friction significantly increases the perturbed radial winds and enhances the convergence.

     

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