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Two series of novel o-(biphenyl-3-ylmethoxy)nitrophenyl compounds (A1-31 and B1-17) were designed as programmed cell death protein 1 (PD-1)/PD-ligand 1 (PD-L1) inhibitors. All compounds showed significant inhibitory activity with IC50 values ranging from 2.7 to 87.4 nM except compound A17, and compound B2 displayed the best activity. Further experiments showed that B2 bound to the PD-L1 protein without obvious toxicity in Lewis lung carcinoma (LLC) cells. Furthermore, B2 significantly promoted interferon-gamma secretion in a dose-dependent manner in vitro and in vivo. Especially, B2 exhibited potent in vivo anticancer efficacy in an LLC-bearing allograft mouse model at a low dose of 5 mg/kg, which was more active than BMS-1018 (tumor growth inhibition rate: 48.5% vs 17.8%). A panel of immunohistochemistry and flow cytometry assays demonstrated that B2 effectively counteracted PD-1-induced immunosuppression in the tumor microenvironment, thereby triggering antitumor immunity. These results indicate that B2 is a promising PD-1/PD-L1 inhibitor worthy of further development.

The northwest vortex (NWV) is a type of mesoscale vortex that appears with a relatively high frequency in Northwest China. To further the understanding of the NWV's evolution, in this study, the moisture and circulation budgets of a long-lived NWV (∼132 h) that appeared in early August 2019 were calculated. This vortex induced a series of torrential rainfall events in Northwest China and Mongolia, which caused severe transmission line faults and urban waterlogging. Synoptic analyses indicate that the NWV was generated in a favorable background environment characterized by notable upper-level divergence and strong mid-level warm advection. The moisture budget shows that the East China Sea and Bohai Sea acted as the main moisture sources for the NWV-associated precipitation, and the water vapor was transported into the rainfall regions mainly by easterly and southeasterly winds. The circulation budget indicates that, during the developing stage, convergence-related vertical stretching was a dominant factor for the NWV's development; whereas, the vortex's displacement from regions with stronger cyclonic vorticity to those with weaker cyclonic vorticity mainly decelerated its development. In the decaying stage, divergence-related vertical shrinking and the net export of cyclonic vorticity due to the eddy flow's transport resulted in the NWV's dissipation. 摘要 西北涡是我国西北地区一类发生频率较高的中尺度涡旋, 其所引发灾害的强度与西南低涡, 高原涡相当, 但相关研究却远远少于前两种涡旋.为了深化对西北涡的认识, 本文利用水汽与环流收支对一次长生命史西北涡 (其在西北地区引发了一系列暴雨过程, 导致了严重的输电线路故障与城市内涝) 进行了研究, 发现, 东海与渤海是此西北涡引发暴雨的主要水汽来源, 东风与东南风则是主要的输送气流. 辐合所引起的垂直伸展是西北涡发展的主导因子, 而涡旋由较强背景涡度区向较弱背景涡度区的移动则一定程度上延缓了涡旋的发展.

Based on hourly precipitation from national surface stations, persistent heavy rainfall events (PHREs) over the Sichuan Basin (SCB) are explored during the warm season (May to September) from 2000 to 2015 to compare synoptic circulations and maintenance mechanisms between different PHRE types. There are two main types of PHREs: one is characterized by a rain belt west of 106°E over the SCB (WSB-PHREs), and the other features a rain belt east of 106°E over the SCB (ESB-PHREs). In total, there are 18 ESB-PHREs and 10 WSB-PHREs during the study period. Overall, the rain belts of WSB-PHREs are along the terrain distribution east of the Tibetan Plateau, while the precipitation intensity of ESB-PHREs is stronger. For the two types of PHREs, the shortwave trough over the SCB and the western Pacific subtropical high act as their favorable background environments, particularly for ESB-PHREs. The water vapor of WSB-PHREs is mainly transported from the South China Sea, whereas for ESB-PHREs the South China Sea and Bay of Bengal are their main moisture sources. The composite vorticity budgets of southwest vortices during their mature stage indicate that the convergence effect is a dominant factor for maintaining the two types of PHREs, and the strong vertical vorticity advection is also favorable, but the relative contribution of vertical advection is larger for WSB-PHREs. 摘要 本文筛选出四川盆地西部 (盆西型) 和盆地东部 (盆东型) 持续性暴雨个例, 深入对比两类持续性暴雨的大气环流特征和直接造成持续性暴雨的西南低涡维持的机理. 四川盆地的短波槽和西太平洋副热带高压的配置有利于持续性暴雨的维持, 盆东型的降水强度较盆西型个例强, 高空急流位置偏南, 南亚高压的强度更强, 高层辐散更强, 对流层中层副热带高压偏东偏南. 盆西型的水汽输送主要来自南海, 而盆东型的水汽输送主要来自南海和孟加拉湾. 合成涡度收支的结果表明散度项是两类持续暴雨中西南涡维持的主要原因, 但盆西型中, 垂直平流的作用更强.

Wind forecast is an essential part of both weather and renewable energy predictions. This study investigated the performances of the weather research and forecasting (WRF) model real-time four-dimensional data assimilation (RTFDDA) and forecasting system for surface wind forecast over China. The system has been running operationally since 2016 with an analysis/forecast cycle every 3 h. The surface wind forecasting skill of the system was evaluated on the 3 km output with the evaluation period of one year from June 2017 to May 2018. The model outputs were validated against observations from the stations over China objectively. The statistics of the system performance was calculated for both station-by-station and the domain average, which include bias, root mean square errors, mean absolute errors, and the correlation between observation and model outputs. The error statistics show that the high-resolution model has advantages in forecasting the detailed structures of weather features and adding values with rapidly refreshing forecast cycles. The verification results demonstrate that WRF tends to forecast surface winds with positive bias for weak wind regimes and negative for high wind regimes. On the other hand, it tends to produce positive bias for lower topography regions and negative for high topography areas. This feature does not change with seasons although the magnitude of wind bias varies with different seasons. The wind forecast bias has the largest diurnal changes in summer, with positive bias close to the coastal areas and the downstream of Yangtze river.

Influenced by strong winds associated with a southeastward-moving Mongolian cyclone, a severe transmission line galloping occurred in Baiyin City, Gansu Province, on 14 April 2020. This caused a tripping incident of the transmission line in this region. Based on the hourly, 0.5° × 0.5°, ECMWF ERA5 reanalysis data, this study investigated the formation mechanisms of the Mongolian cyclone and its associated strong winds. Results from the vorticity budget indicate that the convergence-related vertical stretching and the upward transport of cyclonic vorticity governed formation of the Mongolian cyclone in this event; whereas, tilting and export of cyclonic vorticity from the central region of the cyclone mainly decelerated the cyclone's formation. The kinetic energy (KE) budget shows that the wind associated with the Mongolian cyclone was mainly enhanced by the positive work of the pressure gradient force. Unlike some typical strong wind events in Northwest China, during this event, no significant downward momentum transportation from the upper troposphere was found. The vertical transport of KE exerted a slightly favorable effect on the KE increase around the location where the transmission line galloping trip appeared. In contrast, the horizontal transport mainly caused an export of KE from this region, which applied an overall negative effect on the wind enhancement associated with the Mongolian cyclone. 摘要 受一次向东南方向移动蒙古气旋强风的影响, 2020年4月18日甘肃省白银市的高压输电线路出现了严重的舞动, 这造成了该地区的输电线路跳闸事故.基于0.5度逐小时分辨率的ERA5再分析数据, 本文研究了这次蒙古气旋及其强风的形成机理.涡度收支的结果表明, 辐合相关的垂直伸展以及垂直运动向上的正涡度输送是本次蒙古气旋形成的主因, 而倾斜项的负涡度制造以及从气旋中心区域向外的正涡度输送在一定程度上不利于蒙古气旋的形成.动能收支的结果表明, 蒙古气旋所伴随的风场主要由于气压梯度力的做功而迅速增强.与我国西北部其它的典型强风事件不同的是在本次事件中, 未发现显著的来自于对流层高层的动量下传现象, 垂直的动能输送在本次事件中仅对强风的形成有些许的促进作用.此外, 水平风场对动能的输送作用使得蒙古气旋大风区的动能存在向外的净输出, 这对蒙古气旋强风的生成有一定的延缓作用.

A wall function suitable for the computational fluid dynamics (CFD) simulation of the Atmospheric Boundary Layer (ABL) is developed. This wall function is an improvement of the standard log law but has a unified formula spanning the whole turbulent boundary layer. By modifying a compressible heat transfer wall function, the ability of this wall function is extended to the ABL problems. Hence the ground effects such as heat transfer, pressure gradient can be included in the wall function. The method of introducing the roughness into this king of wall function is also discussed. Several cases including not only the typical turbulent flat plate but also some practically complex ones have been computed as verification of the wall function. The results show that the wall function produces modification to the turbulence values near the boundary, leading to an upgrade of the accuracy especially when the atmospheric boundary effects exist. The impact of these effects on the boundary layer indicates that they are unelectable for complex ABL flow. Besides, this wall function has good efficiency and strong robustness thus it can be applied as a boundary condition into the wind farm simulation for wind energy.

This paper reports an application of Numerical Weather Prediction (NWP) in the heat load forecasting field. The NWP is applied to obtain the correlated weather parameters of the heat load, and then the properly structured Artificial Neural Network (ANN) model is designed to perform the prediction. Satisfactory experimental results are obtained by using actual heat load data in the north of China. The experimental result shows that the proposed NWP based method can predict the heat load precisely. Comparing with the traditional weather forecast based-method, the proposed method can effectively improve the forecasting accuracy.

The performance of the weather research and forecasting (WRF) model relies on the accuracy of the initial field provided by data assimilation. The initial field usually contains large uncertainties, especially for regions where observations are sparse or lacking. Assimilating additional observations is an efficient way to reduce this uncertainty. The moderate resolution imaging spectroradiometer (MODIS) is one of the most critical data sources of various indirect assimilating applications due to its wide swath and remarkable quality. Therefore, assimilating MODIS data into WRF data assimilation (WRFDA) system is meaningful to improve the accuracy of weather forecasts. This study developed a module to directly assimilate the MODIS radiances into the WRFDA based on the 3-D variational data assimilation method and community radiative transfer model. An assimilation experiment was carried out on August 2014, from which the background field has been relatively improved. Specifically, the improvement of the temperature, humidity, and wind speed at the near surface layer is about 0.2°C, 1.2%, and 0.2 m / s , respectively. Additional capabilities and increased potential of MODIS data assimilation based on WRFDA need to be further investigated and tested under various conditions and applications.