Dual‐Doppler lidar observation of horizontal convective rolls and near‐surface streaks

Dual‐Doppler lidar and heliborne sensors were used to investigate the three‐dimensional (3D) structure of the wind field over Sendai Airport in June 2007. The 3D structures of several‐hundred‐meter‐scale horizontal convective rolls (HCRs) in the sea‐breeze layer were observed by the dual‐Doppler lidar. The scale of the HCRs determined by the heliborne sensors roughly agreed with that determined by the dual‐Doppler lidar. Analysis of the dual‐Doppler lidar data showed that the region of upward flow in the HCRs originated in near‐surface low‐speed streaks. This structure is consistent with the results of large‐eddy simulations of the atmospheric boundary layer. The aspect ratios of the HCRs were close to those predicted by linear theories.