江西省“中国天然氧吧”气候资源与创建条件分析

利用江西省1974—2016年气象资料和2016年空气负氧离子、环境空气质量、断面出境水质等监测资料,重点分析了全省旅游气候要素、大气质量、水质状况的时空分布特征,采用天然氧吧评价指标(T/CMSA0002—2017),对江西省"中国天然氧吧"创建条件进行了评估。结果表明,江西北部、中部、东部和南部区域空气负(氧)离子浓度等级均在6—7级,环境空气质量达标率在92%以上,空气质量、出境水质均达到国家Ⅱ类以上标准,旅游资源丰富,交通便利、设施配套完善,综合指标评分高,符合天然氧吧的评价标准。     

青藏高原冬春积雪影响亚洲夏季风的研究进展

青藏高原积雪作为亚洲夏季降水异常的一个预测因子已有很长历史。统计分析表明,青藏高原冬春积雪与印度夏季降水反相关,与我国长江中下游夏季降水多为正相关,不同作者对此现象给出了一些可能的解释,如地表反照率效应和积雪一水文效应。但积雪的这种跨季节滞后影响的具体物理过程仍有争议。另一方面,青藏高原冬春积雪资料存在不确定性,这对相关物理机制的理解造成了很大困难。通过回顾和梳理前人在该领域的研究成果,提出了高原积雪影响亚洲季风的未来研究方向。     

Measuring similarity of mobile phone user trajectories– a Spatio-temporal Edit Distance method

The rapid development of information and communication technologies (ICTs) has provided rich data sources for analyzing, modeling, and interpreting human mobility patterns. This paper contributes to this research area by developing the Spatio-temporal Edit Distance measure, an extended algorithm to determine the similarity between user trajectories based on call detailed records (CDRs). We improve the traditional Edit Distance algorithm by incorporating both spatial and temporal information into the cost functions. The extended algorithm can preserve both space and time information from string-formatted CDR data. The novel method is applied to a large data set from Northeast China in order to test its effectiveness. Three types of analyses are presented for scenarios with and without the effect of time: (1) Edit Distance with spatial information; (2) Edit Distance with time as a factor in the cost function; and (3) Edit Distance with time as a constraint in partitioning trajectories. The outcomes of this research contribute to both methodological and empirical perspectives. The extended algorithm performs well for measuring low-resolution tracking information in CDRs, as well as facilitating the interpretation of user mobility patterns in the age of instant access.     

江西及其临近区域同化系统中不同季节背景误差协方差特征及其对降水预报影响

在不同季节背景下,对比分析多元变量相关的背景误差协方差特征,了解其在天气过程中的作用,可以改进同化系统性能,提高降水数值预报水平。对比分析汛期和非汛期江西及其临近区域多元变量相关的背景误差协方差特征,分别选取2019年汛期和非汛期的2次降水过程,设计2组循环同化试验,探讨多元变量相关的背景误差协方差对江西降水预报效果的影响。结果表明,相较于非汛期,汛期分析变量对风场、温度场和水汽场的贡献值整体上要更大,且汛期各个控制变量的背景场误差更为显著。多元变量试验的降水预报评估效果整体上更好,其汛期预报效果改善更显著。汛期与非汛期的多元变量试验降水预报结果更接近实况,且相对非汛期降水而言,汛期多元变量试验模拟效果更好,模拟的降水分布及强度与实况更为接近。     

2012年12月20-23日巴州寒潮降雪天气的特征分析

利用常规观测资料、自动站、T639客观分析资料,结合天气学原理和天气动力学诊断分析方法,对2012年12月20-23日巴音郭楞蒙古自治州（以下简称巴州）的寒潮天气过程的成因和降雪天气特征进行分析,并给出巴州降雪天气概念模型。结果表明：这次寒潮降雪过程是北欧阻塞高压向东南衰退,导致脊前横槽转成竖槽东南移,高空冷空气南压至40°N附近,造成巴州强降温、强降雪等寒潮天气,降雪阶段关键影响系统是700 hPa上的冷暖切变和风场辐合,水汽主要源自中低层西北方的经向和低层东南方的纬向输送;后续的冷凝降雪和阴雪阶段天气局地特征明显,水汽源自850 hPa至近地层局地的垂直输送。     

Ontogenetic development in the morphology and behavior of loach （Misgurnus anguillicaudatus） during early life stages

Loach （Misgurnus anguillicaudatus） is a commercially important fish in China and an ideal aquaculture species. However, culturists experience high larval and juvenile mortality during mass production. To provide insight into ways to improve larviculture techniques, we describe the morphological characteristics and behavior of loach during the larval and early juvenile stages. Yolksae larvae ranged from 2.8 to 4.0 mm body length （BL） between days 0 to 4; preflexion larvae ranged from 3.6 to 5.5 mm BL between days 4 to 6; flexion larvae ranged from 4.8 to 8.1 mm BL between days 5 and 14; and post-flexion larvae ranged from 7. l to 15.7 mm BL between days 11 to 27; the minimum length and age of juveniles was 14.1 mm BL and 23 d, respectively. Loach are demersal from hatch through to the early juvenile stages. A suite of morphological characteristics （e.g., external gill filament and ventral mouth opening） and behavioral traits have developed to adapt to demersal living. We observed positive allometric growth in eye diameter, head length, head height, and pectoral fin length during the early larval stages, reflecting the priorities in the development of the organs essential for survival. Our results provide a basis for developing techniques to improve the survival of larval and juvenile loach during mass production.     

Green functions with pulsating sources in a two-layer fluid of finite depth

The derivation of Green function in a two-layer fluid model has been treated in different ways.In a two-layer fluid with the upper layer having a free surface,there exist two modes of waves propagating due to the free surface and the interface.This paper is concerned with the derivation of Green functions in the three dimensional case of a stationary source oscillating.The source point is located either in the upper or lower part of a two-layer fluid of finite depth.The derivation is carried out by the method of singularities.This method has an advantage in that it involves representing the potential as a sum of singularities or multipoles placed within any structures being present.Furthermore,experience shows that the systems of equations resulted from using a singularity method possess excellent convergence characteristics and only a few equations are needed to obtain accurate numerical results.Validation is done by showing that the derived two-layer Green function can be reduced to that of a single layer of finite depth or that the upper Green function coincides with that of the lower,for each case.The effect of the density on the internal waves is demonstrated.Also,it is shown how the surface and internal wave amplitudes are compared for both the wave modes.The fluid in this case is considered to be inviscid and incompressible and the flow is irrotational.     

Anomalous atmospheric events leading to Kyushu’s flash floods,July 11–14, 2012

During July 11–14, 2012, deadly floods and landslides triggered by a series of unprecedented heavy rains hit Kyushu, Japan, causing at least 32 deaths and around 400,000 evacuations. We focus on synoptic anomalies identified after inspecting rainfall patterns and documenting the conditions associated with this tragic event using data combined from the Global Rainfall Map in Near Real Time data, the NCEP/NCAR Reanalysis dataset, and the global forecast system. Rainfall maps indicated that there were many heavy rains in Kyushu in these days and this disaster was associated with the pattern of forecasts and standardized anomalies. A weather trough with positive height anomalies appeared, the center of which moved to the north of Japan over this period, which might cause wind anomalies and whereby lots of water vapor were transported to Kyushu area with up to 90 m s^?1, and high values of precipitable water formed with up to 60 mm. These results suggest that a larger-scale pattern is conducive for heavy rainfall and the anomalies put the pattern in context as to the potential for an extreme rainfall event, which can provide insights and methods for predicting extreme events’ or something similar.     

Zircon U–Pb Age and Deformation Characteristics of the Jiama Porphyry Copper Deposit,Tibet: Implications for Relationships between Mineralization,Structure and Alteration

The Jiama copper deposit is one of the largest deposits recently found in Tibet and is composed of three types of mineralization including skarn, hornfels and porphyry. To investigate the relationship between mineralization, structure and alteration, we report new zircon U–Pb age and present field observations on the deformation characteritics associated with the copper mineralization in Jiama. Two main periods of deformation were identified, represented by D₁ and D₂ in Jiama. The first deformation (D₁) occurred around 50 Ma, whereas the second deformation (D₂) that was closely related to mineralization occurred later. Previous zircon U–Pb and molybnite Re–Os dating results indicate that the mineralizatoin occurred at ～15 Ma and thus the D₁ regional deformation significantly occurred before the mineralization time, although the D₁ deformation probably provided important space for the development of significant copper deposition. Our new mapping and observations on the D₂ deformation demonstrate that the mineralization was closely coeval with or slightly later than the time of D₂ deformation. The new U–Pb zircon age further indicates that the aplite formed in ～17.0 Ma and thus the D₂ deformation happened later than this time because the D₂ deformation cut across the aplite, which is proposed to be the key control for copper mineralization. Altered laminated hornfels including three types of alteration (A‐, K‐ and S‐type) were found spatially associated with the D₂ deformation. The type‐A is mainly silicification, with fine sericite or chlorite, as well as abundant disseminated sulphides on fracture surfaces; the type‐S is mainly fine‐grained silicification with patches of chlorite, epidote and common sulphides; the type‐K (potassic alteration) appears to be fine‐grained biotite. Such types of alteration indicate the presence of skarns at depth where ore shoots are located. Taken together, the multiple structural‐magmatic‐mineralization events contributed to the formation of the supergiant Jiama porphyry copper deposit in Tibet. The results have general implication for regional exploration.     

基于STA/LTA和分形维算法的微震事件初至自动拾取方法

精确拾取微地震事件初至是微震定位的关键技术之一。根据STA/LTA和分形维数两种微地震初至拾取方法的原理,采用理论模型数据对两种初至拾取方法进行了测试,并选取不同信噪比的实际数据从初至拾取精度、算法效率两个方面进行了对比。结果表明,对于高信噪比微震事件,两种方法都能获得精度较高的初至,但对于低信噪比微震事件,分形维数与STA/LTA比较其拾取精度相对要高。鉴此,运用STA/LTA和分形维两种算法相结合的微震事件初至拾取方法,对实际数据进行了处理,实现了微震事件初至较为准确的自动拾取。