北半球秋季欧亚遥相关与华西秋雨的关系

利用EOF、相关分析、合成分析等常规统计方法研究华西秋雨与秋季欧亚遥相关(EUa)的关系。结果表明:北半球秋季欧亚遥相关(EUa)指数与华西秋雨呈显著的负相关,两者具有一致的阶段性特征。以1986年为界,20世纪80年代中期之前华西秋雨与EUa指数相关系数波动较大,均在-0.4以上,显著相关区主要集中于四川盆地西南部、贵州大部;20世纪80年代中期之后两者相关系数呈显著增加趋势,且显著相关区域向北偏移,主要集中于四川东北部、重庆大部以及陕西南部地区。EUa异常与华西秋雨的多寡关系显著。EUa正异常年,中高纬度环流形势与水汽特征有利于华西秋雨北部地区降水发生,华西秋雨南部地区缺乏水汽,动力条件不足,不利于秋雨偏多。EUa负异常年,华西秋雨东部地区,表现为有利于降水偏多,而西部地区则特征相反。     

有效的正压原始方程拟能守恒保真（拟）谱模式

本工作遵循保真计算原理与方法,对正压原始方程气象传统全球（拟）谱模式方案进行改造,构造了正压原始方程拟能完全守恒（拟）谱模式新型保真计算方案,解决了正压原始方程的（非线性）计算稳定性问题和拟能守恒整体性质保持问题,改进了相应正压原始方程气象传统全球（拟）谱模式方案的计算效能。新型保真方案的数值实验表明,计算实践中,新方案在解决拟能守恒问题的同时,可解决（非线性）计算稳定问题,并在一定条件下可解决非线性计算收敛性问题。进一步的比较数值实验还表明,计算实践中,新型保真计算方案在提高相应气象传统方案的计算精度、     

ON THE RELATIONSHIP BETWEEN PLANETARY AND SURFACE ALBEDO:MODEL''''S COMPARISON AND VALIDATION

The simple linear relationship between clear-sky planetary and surface albedo can be adopted forcertain accuracy.There are different parameterization schemes of atmospheric correction for differentretrieval models.In this paper,several representative retrieval models are compared and tested withobservational data from HEIhe basin Field Experiment (HEIFE) in western China.Some evaluationsand suggestions on improvement are proposed for models which would be more applicable to plateauand arid areas.     

塔里木河中下游地区气象灾害情况及气象对策

分析了近30年塔里木河中下游地区主要灾害性天气的情况，及对农业、生态和给人们甚至环境带来的严重影响，通过成因分析，提出了一些长期的气象对策和建议。     

Relative contributions of boundary-layer meteorological factors to the explosive growth of PM<Subscript>2.5</Subscript> during the red-alert heavy pollution episodes in Beijing in December 2016

Based on observations of urban mass concentration of fine particulate matter smaller than 2.5 μm in diameter (PM_2.5), ground meteorological data, vertical measurements of winds, temperature, and relative humidity (RH), and ECMWF reanalysis data, the major changes in the vertical structures of meteorological factors in the boundary layer (BL) during the heavy aerosol pollution episodes (HPEs) that occurred in winter 2016 in the urban Beijing area were analyzed. The HPEs are divided into two stages: the transport of pollutants under prevailing southerly winds, known as the transport stage (TS), and the PM_2.5 explosive growth and pollution accumulation period characterized by a temperature inversion with low winds and high RH in the lower BL, known as the cumulative stage (CS). During the TS, a surface high lies south of Beijing, and pollutants are transported northwards. During the CS, a stable BL forms and is characterized by weak winds, temperature inversion, and moisture accumulation. Stable atmospheric stratification featured with light/calm winds and accumulated moisture (RH > 80%) below 250 m at the beginning of the CS is closely associated with the inversion, which is strengthened by the considerable decrease in near-surface air temperature due to the interaction between aerosols and radiation after the aerosol pollution occurs. A significant increase in the PLAM (Parameter Linking Aerosol Pollution and Meteorological Elements) index is found, which is linearly related to PM mass change. During the first 10 h of the CS, the more stable BL contributes approximately 84% of the explosive growth of PM_2.5 mass. Additional accumulated near-surface moisture caused by the ground temperature decrease, weak turbulent diffusion, low BL height, and inhibited vertical mixing of water vapor is conducive to the secondary aerosol formation through chemical reactions, including liquid phase and heterogeneous reactions, which further increases the PM_2.5 concentration levels. The contribution of these reaction mechanisms to the explosive growth of PM_2.5 mass during the early CS and subsequent pollution accumulation requires further investigation.     

模式垂直分辨率对梅雨锋暴雨数值模拟的影响

利用中尺度数值模式MM5(V3),对2003年7月7日~8日发生在武汉地区的一次梅雨锋暴雨过程进行了数值模拟。采用经过简化处理的基于矢量模的双参数最优化处理方法,对模式大气进行了垂直分层。在水平分辨率不变的情况下,数值模式的垂直分层分别采用25层和36层进行了对比模拟试验。模拟结果表明,水平分辨率达到较高的精度后,粗的垂直分辨率会放大模式中地形的作用,造成数值模拟雨带落区的偏差;要得到比较好的模拟结果,需要相应的提高数值模式的垂直分辨率。水平分辨率与垂直分辨率的不协调,会在水平方向上产生虚假的重力波,影响数值模式的模拟结果。     

广西2012年前汛期3次暴雨过程环流和中尺度特征

利用地面和高空常规观测资料、广西自动站降雨资料和雷达资料,对广西2012年前汛期3次暴雨过程环流形势和中尺度特征进行分析,结果表明:3次暴雨过程均有多次高空槽引导冷空气影响广西,并有低涡配合,同时存在中尺度系统的3类触发机制,即500hPa存在干线;850hPa有温度脊配合;广西区域垂直高度上具有:200h Pa有分流区存在,地面辐合线长时间维持少动的上层辐散下层辐合的特征.     

Strain and kinematic vorticity analysis: An indicator for sinistral transpressional strain-partitioning along the Lancangjiang shear zone,western Yunnan,China

This work deals with the preliminary relationship between strain path and strain partitioning pattern in a sinistral transpressional zone,Lancangjiang shear zone,located to the southeast of Tibet.Various ductile rocks provide an opportunity to investigate quantitative finite strain(Rs),kinematic vorticity values(Wm),and proportions of simple and pure shear components.The mean kinematic vorticity values(Wm) were evaluated based on three methods,such as Rs-θ,prophyroclast hyperbolic distribution method(PHD),a...     

Slowness–azimuth corrections of teleseismic events for IMS primary arrays in China

The seismic arrays at Hailar (HILR) and at Lanzhou (LZDM) in China are both primary stations of the International Monitoring System for verifying compliance with the Comprehensive Nuclear Test Ban Treaty. These two stations became operational in 2002 and have since then provided continuous data. In this study, the so-called slowness–azimuth station corrections (SASC) were derived and used to improve the location accuracy of the two arrays. The SASC are found by comparing the back-azimuth and slownesses obtained from array processing to the theoretical values calculated from the reported event locations and the corresponding seismic velocity model. Events reported by the National Earthquake International Center in the time period 2002 to 2006 were used as reference events, and the IASP91 was used as the theoretical velocity model. Small correction vectors with random orientation were found for HILR. Larger correction vectors with systematic vector biases were found for LZDM. The LZDM correction vectors seem to point to the same direction in a large part of the slowness space and may be attributed to local structure. After introducing the SASC for HILR, the standard deviations of back-azimuth and slowness residuals drop from 7.1° to 4.6° and from 1.0 to 0.6 s/°, respectively. For LZDM, these values drop from 22.3° to 10.2° and from 2.9 to 1.1 s/°, respectively. The variations of back-azimuth and slowness residuals were reduced by 32% and 30.2%, respectively, for HILR after SASC and the reductions were 21% and 40.2% for LZDM. The improvements were 77% in back-azimuth and 67% in slowness location for HILR and were 79% and 81% for LZDM after SASC. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.