本文使用柱坐标系下的正压浅水方程组以及斜压扰动方程组,分析得出台风涡旋系统中的涡旋Rossby波划分为两种类型。由于切向基本气流的二阶径向水平切变或者基本气流的垂直涡度在径向方向的变化(β.因子)所导致的涡旋Rossby波称之为第一类涡旋Rossby波(正压涡旋Rossby波),它产生的根本原因是β.因子的作用。这种第一类涡旋Rossby波相对于切向基本气流是单向传播的,其传播方向则与β.因子的正负符号有关。当基本流场垂直涡度ζ:沿着径向r方向增大时,第一类涡旋Rossby波是沿着切向圆周方向逆时针方向传播的;反之则是沿着切向圆周方向顺时针方向传播。如果考虑切向基流的二次垂直切变时,可以得到台风涡旋系统中第二类涡旋Rossby波(斜压涡旋Rossby波)的相速度表达式,第二类涡旋Rossby波产生的物理根源是切向基本流场风速的二次垂直切变或者基本流场径向r方向的平均涡度在空间Z方向上的不均匀性(亦即β.因子)。第二类涡旋Rossby波相对于切向基本气流也是单向传播的,当℃,沿着空间z方向上增大时,第二类涡旋Rossby波就是相对于基本气流V。是顺时针方向传播的;反之则是相对于基本气流逆时针方向传播。在基本流场的风速V存在二次径向水平切变或者垂直切变时,台风中的波动可能是混合的涡旋Rossby波——重力波;而当基本流场的风速V仅仅存在线性切变,不存在二次切变时,此时根本不存在涡旋Rossby波,台风系统中的波动则仅仅是重力惯性波。最后,采用WRF模式对“云娜”台风进行了数值模拟,验证了上述结论。
Based on analysis through barotropic shallow-water equations and baroclinic disturbance equations in the column coordinates,we achieve the results that the vortex Rossby Waves (VRW) of a ty- phoon are separated into two kinds. The first kind is generated owing to the second-order radial horizontal shear of tangential base flow or the radial change of vertical vorticity in it,i. e. ,effects of β. as its root cause. The first kind of VRW (barotropic VRW) travels unidirectionally with respect to tangential base flow,with the direction dependent on the sign (plus or minus) of factor β.. When the vertical vorticity ζt of the base flow increases (decreases) in the radial r, the VRW of first kind propagates counterclockwise (clockwise) in the tangential. If a second-order vertical shear in the tangential base flow is allowed for,then the expression is found for phase speed of VRW of second kind (baroclinic VRW) in a typhoon,whose physical cause consists of a second-order vertical shear of wind speed in the tangential base flow or the zaxis inhomogeneity of mean vorticity in the radial r,i. e. ,effects of β.. The second kind of VRW propagates unidirectionally with respect to tangential base flow. When ζt increases (decreases) in the z direction, it travels clockwise (counterclockwise) with respect to V0. When mean wind speed V in the tangential base flow undergoes a second-order radial horizontal shear or vertical shear, the wave in the typhoon is the mixed VRW and gravity waves. If windspeed V of the tangential base flow experiences linear shear alone, with no second order shear happening,then no VRW occurs at all,implying the wave in a typhoon is solely internal inertia gravity wave.