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Circulation type classification (CTC) is an important method in atmospheric sciences, which reveals the relationship between atmospheric circulation and regional weather and climate. Accurate circulation classification helps to improve weather forecasting accuracy and supports climate change research. China has complex topography and significant spatiotemporal variability in its circulation patterns, making the study of circulation type classification in this region highly significant. This study aims to evaluate the applicability of several mainstream objective CTC methods in the China region. We applied methods including T-mode principal component analysis (PCT), Ward linkage, K-means, and Self-Organizing Maps (SOM) to classify the sea-level pressure daily mean fields from 1993 to 2023 in the study area, and compared the classification results in terms of internal metrics, continuity, seasonal variation, separability of related meteorological variables (e.g., temperature, precipitation), and stability to spatiotemporal resolution. The results show that each method has its advantages in different contexts, with the K-means method showing the best overall performance. Additionally, an optimized approach combining PCT and K-means is proposed.

Persistent cold air pools (CAPs) trap pollutants in valleys for extended periods, leading to reduced visibility and increased air pollution within these valleys. The structure of the persistent cold air pool that occurred in the Lanzhou Valley in December 2016 was simulated using different Planetary Boundary Layer (PBL) scenarios of the Weather Research and Forecasting (WRF) model, and the simulation of the persistent cold air pool was further optimized in these PBL scenarios. The simulation results indicated that weather‐scale dry subsidence and nighttime ground radiation cooling were significant factors contributing to the accumulation of persistent CAPs and pollutants in the Lanzhou Valley. In contrast, convective lifting from the ground led to the dissipation of persistent CAPs and a reduction in pollution within the valley. During persistent CAPs, the PM2.5 concentration and valley heat deficit (Q) were 66.7% and 62% higher, respectively, than during non‐CAP. In the original MYNN scheme, the average PBL height, double turbulent kinetic energy (QKE), and turbulence length scale during persistent CAPs decreased by 30.79%, 50.5%, and 34.4%, respectively, compared to non‐CAP. Compared with the original MYNN scheme, the optimized MYNN scheme shows a significant improvement in the turbulence simulation during the sustained CAPs, resulting in a more stable atmosphere. The PBL height during the sustained CAPs is reduced by 28 m, the diurnal turbulence length scale is reduced by 31.62%, the stability parameter is reduced by 39%, the diurnal mean QKE is reduced by 27.45%, and the QKE impact height is reduced by 100–400 m. During the persistent cold air pools (CAPs) in the Lanzhou Valley, the generation and dissipation reasons of the persistent CAPs in the Lanzhou Valley were discussed using numerical simulations. The impacts of modifying the turbulent length scale parameter and stability constant of the MYNN scheme on the simulation of persistent CAPs in the Lanzhou Valley were also explored. The WRF model was able to simulate three instances of persistent CAPs occurring in the Lanzhou Valley during the study period, although there was some overestimation of nighttime temperatures. During the persistent CAPs, the high‐level airflow ahead of the upper‐level ridge could descend to around 1000 m above the valley, causing warming and increased atmospheric stability in the valley. The turbulence activity on the following day was unable to break this stable atmospheric structure, leading to the formation of persistent CAPs. While the dissipation of the first persistent CAP was due to the downward advection from the upper atmosphere and the uplift of surface airflow, the dissipation of the second and third instances was caused by strong winds blowing from the northeast of the valley, combined with uplift from the terrain. By modifying the turbulent length scale parameter and stability constant of the MYNN scheme, it could identify small‐scale turbulent operations rather than simplifying them into grid movements. This adjustment also enabled the simulation of the decrease in turbulent kinetic energy during persistent CAPs in the Lanzhou Valley, making the simulated events more reasonable.

Xinjiang is located in an arid and semi-arid climate region in China, but Xinjiang Ili river valley is more humid, with higher precipitation intensity and precipitation, which is closely related to the role of the Tianshan Mountains. In this paper, through the NCRP 1° × 1° reanalysis data and the conventional observation data of the Ili River Valley in Xinjiang, the terrain sensitivity experiment conducted by the WRF model is used to analyze the short-term extreme precipitation event of the Ili River Valley from 18–19 of May 2017, to reveal the influence of Tianshan Mountains on the extreme precipitation event of the Ili River Valley. The results show that: (1) The reduction or removal of the terrain will cause a wide range of wind field changes, weaken the vertical upward movement of the windward slope, and the accumulation of water vapor before the windward slope will also be reduced; a large-scale change of the terrain will also affect the direction of water vapor transportation. These effects together lead to a decrease or increase in regional precipitation. (2) “Fuzzy” (smooth) terrain will affect the precipitation simulated by changing the local vertical movement and water vapor transport, which shows that the WRF model’s accurate description of the terrain structure characteristics of mountainous areas is beneficial to accurately simulate the precipitation process on the windward slope area.

Boundary layer development has a significant influence on dust emission and transportation. The effects of surface heat flux on distribution of dust related to BLH (boundary layer height) during a dust event in Northwest China are discussed by numerical simulation. The results show that: the dust emissions start in Dunhuang and strengthen in Minqin with large dust emission fluxes (as high as 3000 μg m−2 s−1) and surface wind speed (up to 20 m s−1). The dust at the early stage mainly concentrates below 500 m above the ground, then lifts over 3000 m above the ground at the strengthening stage, and the concentration in high value center is more than 24,000 μg m−3 at the dust source Dunhuang. The high dust concentration in Minqin maintains at about 1000 m above the ground. Weak dust emission in Minqin makes the dust concentration near the ground less than that in the upper air. The BLH in the high dust concentration center is higher than that in the surrounding area at the emission stage in Dunhuang. Sensitivity experiment with turning off surface heat flux shows obvious decrease of the dust concentration in Dunhuang, with more than four times reduction of the surface dust concentration. The BLH near the high dust concentration area reduces significantly in the sensitivity experiment. However, the gap between the two experiments reduces with the dust development. The BLH in the sensitivity experiment has small spatial differences with uniform distribution in Dunhuang. It means that the thermodynamic contribution is main reason for the distribution differences. The two experiments in Minqin also show that the height of high concentration dust has a difference of about 500 m. The dust lifts with the boundary layer development, but shows different distribution characteristics and influencing factors between Dunhuang and Minqin. Distribution characteristics of a dust related to its boundary layer height and effects of surface heat flux are discussed by numerical simulation during a dust event in Northwest China. At the source Dunhuang, the dust mainly concentrates below 500 m above the ground at the early stage, then lifts over 3000 m at the strengthening stage. At the transport point Minqin, the high dust concentration maintains at about 1000 m above the ground. The boundary layer height in the high dust concentration center is higher than that in the surrounding area at the emission stage. Sensitive experiment without the surface heat flux shows obvious decrease of the dust concentration in Dunhuang, more than four times reduction of the surface dust concentration. The boundary layer height in the sensitive experiment has small spatial differences with uniform distribution. It means that the thermodynamic contribution is a main reason for the distribution differences of the boundary layer height which has a significant influence on the dust diffusion range and vertical distribution.

Over arid regions in north-west China, the atmospheric boundary layer can be extremely high during daytime in late spring and summer. For instance, the depth of the observed convective boundary layer can exceed 3,000 m or even be up to 4,000 m at some stations. In order to characterize the atmospheric boundary-layer (ABL) conditions and to understand the mechanisms that produce such an extreme boundary-layer height, an advanced research version of the community weather research and forecasting numerical model (WRF) is employed to simulate observed extreme boundary-layer heights in May 2000. The ability of the WRF model in simulating the atmospheric boundary layer over arid areas is evaluated. Several key parameters that contribute to the extremely deep boundary layer are identified through sensitivity experiments, and it is found that the WRF model is able to capture characteristics of the observed deep atmospheric boundary layer. Results demonstrate the influence of soil moisture and surface albedo on the simulation of the extremely deep boundary layer. In addition, the choice of land-surface model and forecast lead times also plays a role in the accurate numerical simulation of the ABL height.

The spatial distribution and long-time variation of the deep-developed boundary layer are not well understood in arid and semi-arid regions of northwest China. ERA-Interim (ECMWF Reanalysis data, ECMWF: European Centre for Medium-Range Weather Forecasts) were used to study the deep-developed boundary layer in the five representative areas in summer and then the Weather Research Forecast (WRF) model was applied to simulate and verify its applicability. The results show that the boundary layer heights in the five representative areas are higher in late spring and summer (the highest is 2485~3502 m in June) and lower in autumn, winter and early spring (the lowest is 758~907 m in December). The seasonal variations of the boundary layer height are smaller at 02:00 BJT and 08:00 BJT, while the variations are relatively larger at 14:00 BJT and 20:00 BJT. The atmospheric boundary layer, with heights over 4000 m, generally exists in late spring and summer. The boundary layer heights are higher in the arid region than in the semi-arid region and the deep-developed boundary layer lasts longer in the arid region. The boundary layer heights present reductions from the northwest to the southeast, except for Minqin in the middle north. The numerical simulation results show that there is a significant difference between different combinations of parameterization schemes to simulate the deep-developed boundary layer in these areas. The combination Goddard+SLAB+ACM2 performs better in the extreme arid area, Dunhuang, and the arid areas, Jiuquan and Minqin, whereas the simulation effect of the combination Dudhia+Noah+ACM2 is better in the semi-arid areas, Yuzhong and Lanzhou. The difference between the schemes is related to the determination of the boundary layer height.

Lanzhou is a typical mountainous city with severe air pollution in northwestern China. This study uses hourly observational data of air pollutants at five air quality monitoring sites in Lanzhou from July to December 2015 to discuss data quality control and the representativeness of the monitoring sites (four urban sites and one suburban site). A fuzzy matrix is applied to study primary air pollutants. The results show that of the six routinely monitored pollutants, the primary pollutant is PM10 during the study period. Based on lag correlation analysis and one-way analysis of variance, it is concluded that there are redundant observations at the four urban sites for the timely diffusion and transport of air pollutants from the same general area. The coefficient of divergence (COD) method is then used to evaluate the spatial distribution differences, and the primary air pollutant PM10 shows differences at each site. COD can be used as a positive indicator to describe site representativeness. To evaluate the overall air pollution in the valley, correlation analysis is performed between the PM10 concentration retrieved from aerosol optical depth satellite data and the concentration from the four urban monitoring sites. Among these, the correlation between the workers’ hospital site data and the retrieval data is the highest, passing the 90% confidence level. A new representative evaluation model for air quality monitoring sites, RS = 0.77COD + 0.23Rretrieval, is established by using COD and correlation coefficients between routine observations and satellite retrieval products. From this model, it can be concluded that the biological products institute site in Lanzhou is the most representative site for the evaluation of air pollution out of the four urban air quality monitoring sites from July to December 2015.

Extremely high atmospheric boundary layer is observed over the arid area in Northwest China during late spring and early summer in 2000. By using the community mesoscale weather research and forecasting/Atmospheric Chemistry model (WRF-Chem), numerical simulation is performed to study chemistry tracer diffusion in the extremely high atmospheric boundary layer. Results show that the extremely high atmospheric boundary layer has great influence on the chemistry tracer transportation. The influence is more effective than that driven by wind which is limited by the local terrain. The tracer is controlled in low-level concentration during the daytime but increases rapidly during the nighttime. Sensitive experiments are performed by disturbing soil moisture and albedo to further investigate surface forcing on the atmospheric boundary layer height and the chemistry tracer concentration. It shows that soil moisture or albedo is disturbed as increasing makes the tracer concentration increase in low layer for response of ABL height decrease.

To summarize the cytokine/chemokine levels of anti-N-methyl-Daspartate receptor encephalitis (NMDAR-E) and explore the potential role of these molecules and immune cells in the pathogenic mechanism. The PubMed, Cochrane Library, Embase, and Web of Science databases were searched for various articles that assessed the concentrations of cytokines/chemokines in the unstimulated cerebrospinal fluid (CSF) or serum of patients with NMDAR-E in this systematic review and meta-analysis. The standardized mean difference (SMD) and 95% confidence interval (CI) were calculated by Stata17.0. A total of 19 articles were included in the systematic review from 260 candidate papers, and cytokine/chemokine levels reported in the CSF/serum were examined in each article. This meta-analysis included 17 eligible studies comprising 579 patients with NMDAR-E, 367 patients with noninflammatory neurological disorders, and 42 healthy controls from China, Spain, South Korea, Australia, Czechia, and Sweden. The results indicated that the levels of different cytokines interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-10, IL-13, IL-1β, IL-12, and IL-17 and chemokine C-X-C motif ligand (CXCL)10 in the CSF were significantly higher in NMDAR-E patients with a large effect size. In addition, B cell activating factor (BAFF), CXCL13, and interferon (IFN)-γ levels in the CSF were higher in NMDAR-E patients with a middle effect size. In contrast, levels of IL-2 and IL-4 in the CSF and CXCL13 and BAFF in the serum did not show a significant difference between cases and controls. These analyses showed that the central immune response in NMDAR-E is a process that involves multiple immune cell interactions mediated by cytokines/chemokines, and T cells play an important role in the pathogenesis of immunity. https://www.crd.york.ac.uk/PROSPERO/, identifier (CRD42022342485).

Infectious diseases are considered as a pressing challenge to global public health. Accurate and rapid diagnostics tools for early recognition of the pathogen, as well as individualized precision therapy are essential for controlling the spread of infectious diseases. Aptamers, which were screened by systematic evolution of ligands by exponential enrichment (SELEX), can bind to targets with high affinity and specificity so that have exciting potential in both diagnosis and treatment of infectious diseases. In this review, we provide a comprehensive overview of the latest development of SELEX technology and focus on the applications of aptamer-based technologies in infectious diseases, such as targeted drug-delivery, treatments and biosensors for diagnosing. The challenges and the future development in this field of clinical application will also be discussed.