Relationship Between Fine-Particle Pollution and the Urban Heat Island in Beijing,China: Observational Evidence

Urbanization has led to a significant urban heat island (UHI) effect in Beijing in recent years. At the same time, air pollution caused by a large number of fine particles significantly influences the atmospheric environment, urban climate, and human health. The distribution of fine particulate matter (PM_2.5) concentration and its relationship with the UHI effect in the Beijing area are analyzed based on station-observed hourly data from 2012 to 2016. We conclude that, (1) in the last five years, the surface concentrations of PM_2.5 averaged for urban and rural sites in and around Beijing are 63.2 and 40.7 µg m^?3, respectively, with significant differences between urban and rural sites (ΔPM_2.5) at the seasonal, monthly and daily scales observed; (2) there is a large correlation between ΔPM_2.5 and the UHI intensity defined as the differences in the mean (ΔT_ave), minimum (ΔT_min), and maximum (ΔT_max) temperatures between urban and rural sites. The correlation between ΔPM_2.5 and ΔT_min (ΔT_max) is the highest (lowest); (3) a Granger causality analysis further shows that ΔPM_2.5 and ΔT_min are most correlated for a lag of 1–2 days, while the correlation between ΔPM_2.5 and ΔT_ave is lower; there is no causal relationship between ΔPM_2.5 and ΔT_max; (4) a case analysis shows that downwards shortwave radiation at the surface decreases with an increase in PM_2.5 concentration, leading to a weaker UHI intensity during the daytime. During the night, the outgoing longwave radiation from the surface decreases due to the presence of daytime pollutants, the net effect of which is a slower cooling rate during the night in cities than in the suburbs, leading to a larger ΔT_min.     

全球、中国及云南近百年气温变化的层次结构和突变特征

用文献［１］建立的自适应多分辨数据波滤器进行了全球、中国及云南近百年气温变化的层次结构和突变特征分析。结果表明：（１）全球近百年来的气温变化对于较大时间尺度的演化来说主要特征是变暖,并为３个层次：即１９１９年以前的偏冷期;１９２０－１９７８年偏暖期和１９７９年以后的更暖期。对应于这种较大时间尺度的层次演变,全球的气温变化表现出十分明显的突变特征,两上最明显增暖的突变点分别发生在１９２０年和１９７９     

中国淡水资源现状及农业滴灌水分入渗的研究

中国人均占有水资源量2200m3,仅为世界平均人均占有量的31%,被列为世界13个人均水资源贫乏的国家之一。中国农业是用水大户,灌溉方式比较落后,浪费现象十分严重。如何合理高效地利用有限的水资源,在农业灌水方式、灌溉制度上进行大的变革,此项研究意义深远。本文进行了探索性的实验,提出了新的灌水模式,以期用较少的水取得较高的产出效益。     

Variability in upper-ocean salinity stratification in the tropical Pacific Ocean

Using a gridded array for real-time geostrophic oceanography(Argo) program float dataset, the features of upperocean salinity stratification in the tropical Pacific Ocean are studied. The salinity component of the squared Brunt-V?is?l? frequency N²( N_S²) is used to represent salinity stratification. Layer-max N_S²(LMN), defined as the N_S² maximum over the upper 300 m depth, and halocline depth(HD), defined as the depth w...     

昭通大山包天文气象条件统计分析

采用云南省昭通市昭阳区气象局1960年到1988年间在大山包实地采集的气象数据资料,并根据优良太阳观测台址所要求的各项参数指标,对大山包29年来的气象资料进行了系统的统计分析,发现该候选址点在干季(10月到次年4月)具有年日照时间增长、云量减少、相对湿度降低、风速较小且风向稳定、气候变化具有明显的周期性等特征。考虑到交通条件便利,初步判定它是一个具有潜力的优良太阳观测候选址点。     

硫化物Rb-Sr同位素定年研究进展

针对金属矿床成矿年代确定混乱的问题,国内外许多矿床学家和同位素地球化学家对金属矿物常规同位素定年方法进行了有益的探索研究,尤其是对于矿石矿物以闪锌矿、方铅矿和黄铁矿为主的铅锌矿床,硫化物矿物Rb-Sr同位素定年方法显示出了其独特的优势。结合近几年开展的工作,总结国内外硫化物Rb-Sr同位素定年研究取得的成果、闪锌矿中Rb、Sr的赋存状态与定年机理以及定年适应性问题。采用闪锌矿Rb-Sr同位素组成数据拟合成等时线源自热液流体与闪锌矿之间Rb和Sr的不同分异作用,但并不是所有的闪锌矿均适合该定年技术。要成功获得年龄,需结合野外地质特征采集代表性的矿石样品,并在镜下鉴定基础上挑选合适的单矿物;在分析测试过程中,需尽可能去除次生包裹体和粘土矿物。     

Verification of a 3-D LiDAR Viewer for Discontinuity Orientations

Light detection and ranging (LiDAR) scanners are increasingly being used to measure discontinuity orientations on rock cuts to eliminate the bias and hazards of manual measurements which are also time consuming and somewhat subjective. Typically LiDAR data sets (point clouds) are analyzed by sophisticated algorithms that break down when conditions are not ideal, for example when some of the discontinuities are obscured by vegetation, or when significant portions of the rock face are composed of fractured facets, weathering generated surfaces, or anything that should not be identified as a discontinuity for the purposes of slope stability analysis. This paper presents a simple LiDAR point cloud viewer that allows the user to view the point cloud, identify discontinuities, pick three points on the surface (plane) of each discontinuity, and generate discontinuity orientations using the three-point method. Additionally, a test of our 3-D LiDAR viewer for discontinuity orientations on rock cuts in the United States of America and Canada is presented.     

The role of nonlinearities associated with air-sea coupling processes in El Nino’s peak-phase locking

We use conditional nonlinear optimal perturbation(CNOP)to investigate the optimal precursory disturbances in the ZebiakCane El Nino-Southern Oscillation(ENSO)model.The conditions of the CNOP-type precursors are highly likely to evolve into El Nino events in the Zebiak-Cane model.By exploring the dynamic behaviors of these nonlinear El Nino events caused by the CNOP-type precursors,we find that they,as expected,tend to phase-lock to the annual cycles in the Zebiak-Cane model,with the SSTA peak at the end of a calendar year.However,El Nino events with CNOPs as initial anomalies in the linearized Zebiak-Cane model are inclined to phase-lock earlier than nonlinear El Nino events despite the existence of annual cycles in the model.It is clear that nonlinearities play an important role in El Nino’s phase-locking.In particular,nonlinear temperature advection increases anomalous zonal SST differences and anomalous westerlies,which weakens anomalous upwelling and acts on the increasing anomalous vertical temperature difference and,as a result,enhances El Nino and then delays the peak SSTA.Finally,we demonstrate that nonlinear temperature advection,together with the effect of the annual cycle,causes El Nino events to peak at the end of the calendar year.     

An event-based spatiotemporal data model (ESTDM) for temporal analysis of geographical data

Abstract

Representations historically used within GIS assume a world that exists only in the present. Information contained within a spatial database may be added-to or modified over time, but a sense of change or dynamics through time is not maintained. This limitation of current GIS capabilities has recently received substantial attention, given the increasingly urgent need to better understand geographical processes and the cause-and-effect interrelationships between human activities and the environment. Models proposed so-far for the representation of spatiotemporal data are extensions of traditional raster and vector representations that can be seen as location- or feature-based, respectively, and are therefore best organized for performing either location-based or feature-based queries. Neither form is as well-suited for analysing overall temporal relationships of events and patterns of events throughout a geographical area as a temporally-based representation.

In the current paper, a new spatio-temporal data model is proposed that is based on time as its organizational basis, and is thereby intended to facilitate analysis of temporal relationships and patterns of change through time. This model is named the Event-based Spatio Temporal Data Model (ESTDM). It is shown that temporally-based queries relating to locations can be implemented in an efficient and conceptually straightforward manner using ESTDM by describing algorithms for three fundamental temporally-based retrieval tasks based on this model: (1) retrieving location(s) that changed to a given value at a given time, (2) retrieving location(s) that changed to a given value over a given temporal interval, and (3) calculation of the total area that has changed to a given value over a given temporal interval. An empirical comparison of the space efficiency of ESTDM and compressed and uncompressed forms of the ‘snapshot’ model is also given, showing that ESTDM is also a compact representation of spatio-temporal information.