To obtain high precision wind profile and turbulence products and fully understand the application potential of wind lidar, quality control of Doppler wind lidar with five-beam swing (DBS5) mode is investigated in this work using radial velocity and signal-to-noise ratio (SNR). Three-dimensional wind and turbulence measurements by the DBS5 mode of wind lidar are systematically evaluated based on measurements of a three-dimensional ultrasonic anemometer mounted on a tower. The results show that the wind lidar exhibits excellent observational accuracy with root mean square errors (RMSEs) as low as 0.4 m/s, 0.1 m/s, 0.1 m/s, 0.1 m/s, and 0.5 m²/s² for horizontal wind speed (WS), vertical velocity (w), standard deviation of vertical velocity (σ_w), friction velocity (u_*), and turbulent kinetic energy (TKE), respectively at the height of 140 m. Moreover, the impacts of time scale, elevation angle, and spatial scale on observational accuracy of wind lidar are investigated. The results indicate that variations in time scale have little impact on observational accuracy, while elevation angle may affect the accuracy of TKE. Additionally, the RMSEs of WS and TKE gradually increase with increasing spatial scale, while the accuracy of w, σ_w, and u_* remain relatively stable. Further investigation of profiles of turbulence and vertical velocity under clear-sky conditions in Beijing indicates that the power spectra of vertical velocity is consistent with the classical −5/3 scaling law at different periods and heights, whereas white noise appears in the high-frequency region and intensifies with increasing height, especially above the boundary layer. Finally, the vertical turbulence of low-level jets (LLJs) observed by Doppler wind lidar is stronger below the jet height and weaker in and above the jet height.

The similarities and differences in environmental conditions between daytime and nighttime torrential precipitation processes in North China have not been fully clarified. Based on precipitation data collected at 981 surface meteorological stations and ERA5 reanalysis data, the spatial and temporal distribution characteristics and environmental conditions of daytime and nighttime types of torrential precipitation processes in North China during the period from May to September of 2013—2023 are comprehensively analyzed. The objective classification method of the obliquely rotated T-mode principal component analysis is used to classify the circulation situations of daytime and nighttime types of torrential precipitation processes, and the characteristics of environmental physical variables of their corresponding circulation situations are then compared and analyzed. Direct comparison reveals that the environmental conditions of the nighttime heavy precipitation process in North China are different from that of the daytime heavy precipitation process, which provides an important basis for deepening our understanding of the formation mechanism of nighttime heavy rainfall in North China. The results show that the nighttime type torrential precipitation processes in North China develop more often after midnight, and have more occurrences over more concentrated regions, while the daytime processes and the first half-night precipitation of the nighttime processes have stronger convection and they mainly occur in July and August. Moisture of nighttime type is richer than that of daytime type, while CAPE of daytime type is higher than that of nighttime type. The distributions of both 850 hPa and 500 hPa temperature difference and 850 hPa vertical velocity are similar between the two types. Low-level wind speed and 0—1 km vertical wind shear are significantly higher in the nighttime type than in the daytime type. Low troughs and vortices at the edge of the subtropical high are the main synoptic systems influencing torrential precipitation processes in North China. The distribution characteristics of physical variable of the environments in different types of circulation situations are somewhat different. Moisture of deep trough circulation of daytime type and cold vortex circulation of nighttime type are the worst. 0—6 km vertical wind shear (SHR₆) and 0—3 km vertical wind shear (SHR₃) are generally not strong. SHR₆ of daytime torrential precipitation processes is slightly stronger than that of nighttime type, and SHR₃ of nighttime torrential precipitation processes is slightly stronger than that of daytime type. The above results indicate that the nighttime heavy rainfall over North China is closely related to the East Asian summer monsoon, which is characterized by abundant water vapor, high θ_se value, appropriate CAPE value and strong wind speed in the lower atmosphere. The low-level wind field and SHR₃ distribution indicate that one of the dominant factors of nighttime heavy rainfall over North China is the diurnal variations of low level jet or strong wind speed.

Retrievals of satellite-observed emissions of atmospheric pollutants and greenhouse gases provide essential information and data for understanding the sources of these key atmospheric compositions and for implementing precise emission control measures. Over the past two decades, significant progress has been made in the field of emission inversion, with Chinese researchers playing a substantial role. In celebration of the 100th anniversary of the Chinese Meteorological Society and Acta Meteorologica Sinica, this paper systematically reviews the advances in satellite-based emission inversion research by Chinese scientists during this period. (1) Several widely used inversion methodologies, including data assimilation, local mass balance, Gaussian models, two-dimensional (2D) models, and machine learning, are briefly summarized. (2) Emission inversion studies focusing on major atmospheric pollutants— such as nitrogen oxides (NO_x), ammonia (NH₃), formaldehyde (HCHO), glyoxal (CHOCHO), sulfur dioxide (SO₂), and carbon monoxide (CO)—as well as greenhouse gases like carbon dioxide (CO₂) and methane (CH₄), are systematically elaborated. (3) Finally, the historical evolution of inversion methods and target species, challenges in current satellite-based emission inversion, and future research directions are discussed to promote more accurate quantification of atmospheric pollutants and greenhouse gas emissions. It is worth noting that contributions from Chinese researchers have provided critical scientific support to environmental protection and carbon neutrality efforts in China.

In 2023, the central part of the Hexi Corridor experienced an extreme high temperature and drought that would occur once every 60 years, which adversely affected local agricultural production and ecological environment, causing serious economic losses. This study uses various observational datasets to discuss the characteristics and effects of the high-temperature and drought in the central Hexi Corridor in 2023 from perspectives of meteorology, hydrology, ecology and agriculture. We further examine the responses of summer precipitation in the central Hexi Corridor to anomalous atmospheric circulation and sea surface temperature (SST). The datasets used in this study include monthly precipitation and temperature data during 1951—2023 from six national basic stations in the central Hexi Corridor, the Heihe river runoff data from Yingluoxia hydrological station in the upper reaches of the Heihe river, the FY-3D/MERSI satellite data, the GF-1 satellite data, and the NCEP/NCAR monthly mean reanalysis data, and 88 atmospheric circulation indexes and 26 SST indexes provided by National Climate Centre. The results show that precipitation and average temperature in the central part of the Hexi Corridor from May to September 2023 both exceeded historical extremes, with precipitation reached a new historical low and temperature reached a new historical high. The combined effect of high temperature and low precipitation significantly exacerbated the intensity of drought. In the middle Qilian mountains, the average snow cover area decreased by 45.8%, the annual runoff decreased by 15%, the main reservoir area decreased by 25.8%—66.0%. The characteristics of drought spread are meteorological drought—hydrological drought—ecological and agricultural drought. We find that precipitation in the central Hexi Corridor from May to September had significant multi-scale oscillations in 5, 11, 17 and 32 a, and multiple time scales showed that 2023 was in a period of less oscillation. When the drought in the central Hexi Corridor was observed, the atmospheric circulation anomalies included a southward shifted ridge line of the western Pacific subtropical high, an eastward shifted ridge point of the western extension, a westward shifted ridge point of the South Asian high pressure, a weaker than normal Indian low, a smaller polar vortex area in the northern hemisphere and Asia, a stronger blocking high in the middle and high latitudes of Asia, and increased longitudinal coverage of the westerly circulation in Eurasia. Meanwhile, positive SST anomalies occurred in the Nino3 area and the west wind drift region, while negative SST anomalies occurred in the Kuroshio region.

Significant progress has been made in numerical forecasting of typhoon tracks and intensity, yet meeting the needs of operational forecasting remains challenging. Based on the high-resolution Weather Research and Forecasting (WRF) model, eight sets of combination experiments are conducted with different model initial conditions, initialization times, and microphysical parameterization schemes. The results indicate that the model initial condition exhibits the highest sensitivity in forecasting the track of typhoon Lekima (1909). Representative experiments are selected based on track errors, and sensitivity experiments are conducted to further explore the mechanisms responsible for significant differences in typhoon track forecasts arising from different model initial conditions. The results indicate that accurate forecasting of the strength and extent of the western Pacific subtropical high (WPSH) plays a crucial role in determining the quality of typhoon track predictions. An overestimation of the WPSH in the initial field leads to a subsequent overestimation of WPSH, which blocks the typhoon that moves westward and northward along the WPSH and its moving speed is slowed. This results in significant errors in the typhoon track forecasting. Additionally, forecast errors of the typhoon inner core structure at different stages are related to the predicted typhoon track. Vertical wind shear in the large-scale circulation field may be a significant factor contributing to this error. Moreover, an overestimation of the WPSH extent and intensity leads to a deeper asymmetric distribution of horizontal wind speed near the typhoon, which contributes to the occurrence and development of deep convection. This is an important reason for the slower moving speed of the typhoon.

Hong Kong is a coastal city in southern China. In the nineteenth century, Hong Kong's shipping industry had been well developed, serving as an important entrepot in the region. The Hong Kong Observatory (HKO) was established in 1883. Early operations of the HKO were all related to the shipping industry at the time, including meteorological observations and tropical cyclone warning service. The HKO has been conducting meteorological measurements at its Headquarters in Tsimshatsui since 1884. The long-term weather observations document the variations of climate in Hong Kong caused by global climate change and local urbanization. In 2017, the HKO Headquarters received the World Meteorological Organization's recognition as one of the first batches of centennial observing stations in the world. In more than a century, the HKO's services have evolved in pace with the increasing expectations and requirements of the modern society. During the period, the HKO made use of advanced technologies from time to time in tandem with its operational developments. Looking ahead, the HKO will further strengthen the cooperation with meteorological authorities in mainland China and the Greater Bay Area, playing the role of connecting the world to promote close meteorological cooperations regionally and internationally, and improving the ability to prevent natural disasters and respond to emergencies.