Lidar Observations of the Typhoon Boundary Layer Within the Outer Rainbands

• Published in: Boundary-layer meteorology Vol. 171; no. 2; pp. 237 - 255
• Main Authors: Tsai, Yuan-Shiang, Miau, Jiun-Jih, Yu, Chao-Ming, Chang, Wan-Ting
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.05.2019; Springer; Springer Nature B.V
• Subjects: Agreements; Analysis; Atmospheric boundary layer; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Boundary layers; Computer simulation; Coriolis force; Coriolis parameters; Doppler lidar; Doppler sonar; Earth and Environmental Science; Earth Sciences; Empirical analysis; Energy industry; Friction; Ground-based observation; Hurricanes; Intervals; Laboratories; Lidar; Meteorology; Mixed layer; Musical groups; Optical radar; Parameters; Power law; Profiles; Rain; Rainbands; Remote sensing; Research Article; Scaling; Surface boundary layer; Surface layers; Turbines; Typhoons; Velocity; Wind; Wind speed; Typhoon boundary layer; Mixing-length theory; Wind-speed profiles; Lidar measurement; Surface layer
• ISSN: 0006-8314; 1573-1472
• DOI: 10.1007/s10546-019-00427-6

The typhoon boundary layer within the two super typhoons Dujuan and Soudelor is observed using ground-based Doppler lidar up to a height of 240 m, and primarily in the outer rain-bands. The mean wind-speed profiles are analyzed over 1-h intervals and two longer intervals, representing the stages of the typhoons’ approach and departure, respectively. In agreement with surface-layer parametrizations related to finite mixing-length theory, the hourly mean wind-speed profiles demonstrate that the scaling parameter u ∗ o / f c , where u ∗ o denotes the surface friction velocity, and f c denotes the Coriolis parameter, determines the depth the surface layer, and governs the boundary-layer formation in the mixed layer. With large values of u ∗ o / f c , the dominance of surface friction extends the logarithmic layer to the uppermost level of the present observations. In contrast, with small u ∗ o / f c values, the effect of the Coriolis parameter increases the wind speed with respect to the logarithmic profile above the surface layer. That the averaged wind-speed profiles may be described by finite mixing-length theory, the empirical Deaves and Harris model, as well as the power-law profile, suggest these approaches are appropriate for simulations of the typhoon boundary layer.