A NOVEL METHOD FOR CALCULATING VERTICAL VELOCITY：A RELATIONSHIP BETWEEN HORIZONTAL VORTICITY AND VERTICAL MOVEMENT

• Published in: Journal of Tropical Meteorology Vol. 22; no. 2; pp. 208 - 219
• Main Author: 丁治英 赵向军 高松 罗亚丽
• Format: Journal Article
• Language: English
• Published: Guangzhou Guangzhou Institute of Tropical & Marine Meteorology 01.06.2016
• Subjects: Methods; Q矢量散度; Storms; Velocity; Wind shear; 垂直运动; 垂直速度; 水平涡度; 计算运动学; 连续性方程; 逆时针旋转; 顺时针旋转
• ISSN: 1006-8775
• DOI: 10.16555/j.1006-8775.2016.02.011

The present work provides a novel method for calculating vertical velocity based on continuity equations in a pressure coordinate system.The method overcomes the disadvantage of accumulation of calculating errors of horizontal divergence in current kinematics methods during the integration for calculating vertical velocity,and consequently avoids its subsequent correction.In addition,through modifications of the continuity equations,it shows that the vorticity of the vertical shear vector（VVSV） is proportional to-ω,the vertical velocity in p coordinates.Furthermore,if the change of ω in the horizontal direction is neglected,the vorticity of the horizontal vorticity vector is proportional to-ω.When ω is under a fluctuating state in the vertical direction,the updraft occurs when the vector of horizontal vorticity rotates counterclockwise;the downdraft occurs when rotating clockwise.The validation result indicates that the present method is generally better than the vertical velocity calculated by the ω equation using the wet Q-vector divergence as a forcing term,and the vertical velocity calculated by utilizing the kinematics method is followed by the O＇Brien method for correction.The plus-minus sign of the vertical velocity obtained with this method is not correlated with the intensity of d BZ,but the absolute error increases when d BZ is 〉=40.This method demonstrates that it is a good reflection of the direction of the vertical velocity.