### Observation of Stable Marine Boundary Layer by Shipborne Coherent Doppler Lidar and Radiosonde over Yellow Sea

Xiaochun ZHAI1,2(),Songhua WU1,3(),Bingyi LIU1,3,Jiaping YIN4,Hongwei ZHANG1

1. 1. Ocean Remote Sensing Institute, Ocean University of China, Qingdao 266100, China
2. Deutsches Zentrum für Luft-und Raumfahrt e.V. (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen 82234, Germany
3. Laboratory for Regional Oceanography and Numerical Modeling, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, China
4. Qingdao Leice Transient Technology Ltd., Qingdao 266100, China
• Received:2020-10-11 Accepted:2020-11-20 Online:2020-12-20 Published:2021-01-15
• Contact: Songhua WU E-mail:zhaixiaochun@163.com;wush@ouc.edu.cn
• About author:Xiaochun ZHAI (1992—), female, majors in atmospheric dynamics and turbulence.E-mail: zhaixiaochun@163.com
• Supported by:
National High Technology R&D Program of China(2014AA09A511);National Natural Science Foundation of China(41471309);National Natural Science Foundation of China(41375016);National Natural Science Foundation of China(61975191);National Key R&D Program of China(2016YFC1400904)

Abstract:

Shipborne observations obtained with the coherent Doppler lidar (CDL) and radiosonde during 2014 campaign were used to study the structure of marine boundary layer in the Yellow Sea. Vertical wind profiles corrected for ship motion was used to derive higher-order statistics, showing that motion correction is required and significant for turbulence analysis. During a day with weak mesoscale activity, a complexed three-layer structure system was observed. The lowest layer showed a typical stable boundary layer structure feature. An aerosol layer with abrupt variation in wind speed and relative humidity always appeared at the middle layer, the formation of which may be due to Kelvin-Helmholz instability. The top layer encountered a dramatic change in wind direction, which may result from the warm advection from the Eurasian continent on the basis of backward trajectory analysis. Furthermore, the MABL height in stable regime was derived from potential temperature, CDL signal-to-noise ratio (SNR) and CDL vertical velocity variance, respectively. The stable boundary layer (SBL) height in SBL can be derived from the inversion layer of potential temperature profile, and the mixing height in SBL can be retrieved from the vertical velocity variance gradient method. Neither the SBL height nor the mixing height is in agreement with the height retrieved from CDL SNR gradient method because of different definition and criterion. One of the limitations of SNR gradient method for MABL retrieval is that it is easier to be affected by the lofted decoupled aerosol layer, where the retrieved result is less suitable. Finally, the higher-order vertical velocity statistics within the marine stable boundary layer were investigated and compared with the previous studies, and different turbulence mechanisms have an important effect on the statistics deviation.