The dynamic, thermal and material structures of sea-land breeze circulation at the coastal of Ningbo, East China Sea

The high-resolution dynamic, thermal and material structures of sea-land breeze circulation (SLB) were observed at the coastal of Ningbo, East China Sea from November 2019 to May 2020, with wind profile lidar, microwave radiometer and particulate matter lidar. The results show that SLB occurs more frequently in spring (22 days) than in winter (18 days). The horizontal wind speed is generally less than 8 m·s−1, and the vertical wind speed is less than 0.17 m·s−1. The maximum U wind component is 3.2 m·s−1 and 2.4 m·s−1 in spring and winter, respectively. The U wind component and its gradient show that the circulation heights of sea breeze in winter and spring are 1.3 km and 1.8 km, respectively. The heights of land breeze (LB) in winter and spring are 0.65 km and 1.1 km, respectively. The horizontal wind speed shows that the prevailing heights of sea breeze (SB) in winter and spring are 0.9 km and 1.3 km, respectively. The prevailing heights of LB in winter and spring are 0.4 km and 0.7 km, respectively. The boundary layer height during SB is about 1.1 km, and the residual layer height during LB is about 0.6 km at night. The development of SLB in winter is obviously different from that in spring, the transition process is about 2 h shorter than that in spring. With the rapid change of wind speed and direction, the turbulent kinetic energy reaches 3.5m2·s−2 on about 1.0–1.2 km in the circulation. The maximum of TKE in spring is higher than that in winter. The changes of temperature and absolute humidity are similar in winter and spring. Particulate matter was confined within the boundary layer of SLB, much lower than the circulation height. When the SB speed increases, the PM10 concentration decreases. PM10 has a zonal distribution at 400 m in spring.