Xingxu Zhou

The seasonal variation of the sea‐land breeze (SLB) circulation is investigated in a typical coastal city Qingdao, China, using continuous 2‐year observation data from Doppler LiDAR. The frequency of SLB varies seasonally, peaking in July and bottoming in January. The establishment time of the sea breeze is primarily concentrated between 08:00 LST and 12:00 LST, with its onset occurring approximately 1 hr earlier in spring and summer compared to autumn and winter. The top of the land‐breeze circulation is lower than that of the sea‐breeze circulation in all seasons and shows a decreasing trend over time. The top height of the sea‐breeze circulation, apart from a gradual decline in spring, exhibits complex curvilinear changes in other seasons. It should be noted that a negative sea‐land temperature difference (SLTD) is not a necessary condition for the formation of SLB in this study. Instead, the inversion layer structure is commonly found during the nocturnal hours of SLB days, resulting in a significant reduction in the atmospheric boundary layer height (ABLH) compared to the average, with a decrease of about 50% in winter and 10%–30% in other seasons. This stable ABL structure suppresses turbulent activity and enhances the wind speed difference between the lower and upper layers during the day, as well as the momentum transfer, which can be used to explain the development mechanism of the SLB circulation.

Inverse energy cascade (IEC), where energy moves from small to large eddies, has been debated, with limited observational evidence. This study used 19 months of Doppler Lidar data from Qingdao, China, to examine IEC associated with gusts. We found IECs occurred 15% of the time at 50 m height. When near‐surface wind speeds exceeded 11 m·s⁻¹, IEC frequency and intensity increased, indicating that strong winds are a critical driver of IEC. This study suggests that the reduction in the drag coefficient under high wind conditions may generate IEC and gusts, consequently influencing energy transfer throughout the boundary layer and lower troposphere. Analysis using the four‐quadrant model revealed IECs are linked to changes in momentum from ejections and inward interactions, even in weak background fields. The study supports that IECs are more prevalent and highlights their role in the lower atmosphere, contributing to an improved understanding of land‐atmosphere coupling.

Concurrence of temperature inversion (TI) and humidity inversion (HI) is a particular configuration of the atmospheric boundary layer with important implications for early warning of fog formation. With a microwave radiometer device deployed in a 2‐month winter campaign at a coastal island in Qingdao, China, we here examine the relationship between TI and HI, and investigate the underneath mechanisms. Cases of temperature inversion are further divided into surface‐based temperature inversion (SBTI) and elevated temperature inversion (ETI), which show different relationship with HI. SBTI typically occurs at night with its strength significantly and positively correlated with HI. ETI also shows a high degree of temporal overlap with HI, but its strength has no obvious relationship with HI. The main explanation for this phenomenon is that ETI may block the vertical diffusion of water vapor, resulting in the formation of HI.

Wind gusts are sudden, brief increases in wind speed that have important implications for wind power generation, building design, aviation and marine safety. However, wind gusts in the Plateau and coastal plain are very different. In this paper, the gust characteristics are explored and compared at two sites in the same latitude—Xining, a city in the eastern Tibetan Plateau, and Qingdao, a city in the coast in China—using Doppler lidar data. The results indicate that the wind gusts in Xining are more intense and occur at a higher height than those in Qingdao. Though mean winds and turbulence significantly influence gusts, the turbulence intensity is responsible for the differences in gust, and high turbulence in the eastern part of the Tibetan Plateau is inferred. These results provide observational evidence for wind gusts over the complex terrain of the Tibetan Plateau and are useful for studying their impact on important aspects, such as flight safety.

Wind gusts are common small‐scale weather phenomena characterized by a rapid increase in wind speed over a short period of time. Wind gusts affect a wide range of interests, including aviation safety, wind energy and professional skiing, while strong gusts can also cause severe weather events and limit visibility. However, the characteristics of gusts in the lower troposphere are not yet well understood, especially at the top of the boundary layer. In this paper, the gust parameters in the lower atmosphere at different heights and their diurnal variation characteristics are examined based on Doppler lidar data from the gentle coastal topography of Shandong Province, China. The results show that all the gust parameters have distinct stratification characteristics, with significantly different diurnal variations below 400 m, between 400 and 1,200 m, and above 1,200 m (above the ground, same below). Wind gusts are considered to be the result of turbulent disturbances superimposed on the background airflow, and strong turbulence could cause the instantaneous winds to significantly deviate from the mean airflow. The magnitude of the peak gust is mainly controlled by the mean flow, but the gust factor, which is the ratio of the peak gust to the mean flow, is almost independent of the mean flow and has a strong positive correlation with the turbulence intensity. These results imply that gusts of different properties occur at varying altitudes, with differences depending on turbulence intensity and mean airflow, and provide an observational basis for studies of gust structure.