Method of Modeling Atmospheric Optical Turbulence

The intensity and distribution of optical turbulence are important parameters to evaluate an observing station. A modeling method to obtain n atmospheric optical turbulence parameters, including the C2_n pro?le, coherent length, coherent time, seeing, isoplanatic angle, and scintillation index by using meteorological parameters are presented. The accomplishment of this method, the con?guration of the WRF model (Weather Research and Forecasting Model), and the veri?cation of calculated results are introduced. The reliability of the method is con?rmed preliminarily by comparing the calculated results with the DIMM (Differential Image Motion Monitor) measurements.     

Positive and negative spillover of pro-environmental behavior: An integrative review and theoretical framework

A recent surge of research has investigated the potential of pro-environmental behavior interventions to affect other pro-environmental behaviors not initially targeted by the intervention. The evidence evaluating these spillover effects has been mixed, with some studies finding evidence for positive spillover (i.e., one pro-environmental behavior increases the likelihood of performing additional pro-environmental behaviors) and others finding negative spillover (i.e., one pro-environmental behavior decreases the likelihood of additional pro-environmental behaviors). Different academic disciplines have investigated this question, employing different methodologies and arriving at divergent findings. This paper provides a unifying theoretical framework and uses the framework to review the existing research on pro-environmental behavior spillover. Our framework identifies different decision modes as competing mechanisms that drive adoption of initial pro-environmental behaviors, with different consequences for subsequent pro-environmental behaviors, leading to positive, negative, or no spillover. Attribution of the initial pro-environmental behavior to either an external motivator (e.g., a price signal) or internal motivator (e.g., self-identity) also matters. In addition, the characteristics of and similarity between initial and subsequent pro-environmental behaviors can be expected to moderate predicted spillover effects. We explore the implications of our model for policymakers and practitioners, and suggest key areas where future research on the topic would be most beneficial.     

海草床沉积物有机碳研究综述

海草床具有重要的生态系统服务功能,可以为海洋生物提供栖息地和食物来源,同时还具有重要的碳储存功能,海草床“蓝碳”功能日益受到学术界的重视,据研究全球每年海草床的碳埋藏量高达(2.7~4.4)×10⁷ MgC。近年来,由于人类活动的影响,世界范围内海草床衰退严重,导致海草床沉积物有机碳储量降低。本文综述了全球海草床沉积物有机碳的来源、组分、储量以及指示作用;从物理、化学和生物三方面讨论了影响海草床碳储量的环境因素。最后提出了未来主要研究方向,主要包括加强海草床碳通量普查,分析全球气候变化背景下海草床沉积物有机碳的变化机制,明确海草床碳储量流失速率,研究海岸带工程对海草床沉积物有机碳的影响。评估海草床沉积物有机碳储量及变化机制可以为全球海洋蓝碳研究提供科学依据。     

Effects of Compost Addition on Pyrene Removal from Soil Cultivated with Three Selected Plant Species

A greenhouse pot experiment was conducted to investigate the effect of compost addition on the phytoremediation ability of Medicago sativa, Brassica napus, and Lolium perenne in soils contaminated with pyrene. Pyrene concentrations were evaluated after 90 days in contaminated uncultivated amended‐soil, cultivated amended‐soils, and shoots and roots of the three plant species. The addition of compost enhances significantly pyrene dissipation from 16 to 26% in uncultivated soil, whereas in cultivated soils it appears not to have any significant effect on pyrene dissipation, neither pyrene was detectable in shoots and roots of the three species examined. The high partition coefficient of pyrene to compost dissolved organic matter (DOM) and the molar absorptivity values at 280 nm (ε₂₈₀) indicate a high affinity of pyrene to compost DOM molecules, likely due to their aromatic character. These results suggest that compost improves pyrene removal from soil, possibly by promoting its adsorption onto compost DOM. This property is very important in indicating that compost can be used, besides for its amendment capacity, also as a potential tool for remediation of contaminated soils.     

Identifying determinants of urban growth from a multi-scale perspective: A case study of the urban agglomeration around Hangzhou Bay,China

Analyzing the spatial determinants of urban growth is helpful for urban planning and management. In a case study of urban agglomeration around Hangzhou Bay (China), four landscape metrics (total area, total edge, landscape shape index and aggregation index) were used to describe the landscape characteristics of the urban growth at two block scales (4 km and 7 km) during two temporal intervals (1994–2003 and 2003–2009). Spatial autocorrelation regression was employed to identify the geographic determinants of the urban landscape changes. The results indicated that the urban landscapes became more dominant, unstable, irregular and compact, especially in the centers of cities. These changes exhibited notable spatial variations and spatial autocorrelation at the two block scales. The distances to national and provincial roads influenced the urban pattern changes. The impacts of the urban centers on urban expansion gradually declined with the urbanization progress. The slope factor was the most influential determinant of urban growth. Our study emphasized the importance of considering the autocorrelation and scale effects when analyzing the determinants of urban growth. These findings may help land planners create policies and strategies for future urban development.     

“They want to live in the Tremé, but they want it for their ways of living”: gentrification and neighborhood practice in Tremé, New Orleans

In this study, I deploy an ethnographic approach to analyze the detrimental effects of gentrification on longstanding residents in New Orleans’ Tremé neighborhood. I focus on conflicts between long-established residents and gentrifiers over the use of neighborhood space on a day-to-day basis as a means for examining the consequent changes in neighborhood life. As their neighborhood gentrifies, long-term residents of Tremé must contend with greater policing, the erosion of place-based knowledge, practices, and cultural traditions, the loss of social networks, and the closure of vital neighborhood institutions. These changes in neighborhood life provide a starting point from which to begin to understand the broader effects (beyond displacement) that longstanding residents experience as a result of gentrification.     

国外大型事件申办热潮:政治视角的解读

对大型事件影响力共识的缺乏与其申办热情成为悖论,一方面其影响效应尚模糊不清,并引起学界的质疑和争议;另一方面城市的申办和举办热情有增无减,因而隐藏在经济目标之下的非经济动机值得关注。文章从已有文献中厘清国外大型事件的申办动机、申办过程及事件后所表征的政治效应,从政治视角解释当前国外大型事件的申办热潮。主要结论如下:1)超越"事件"本身来看,大型事件作为政府政策工具的角色突显;2)大型事件的时效性使得城市得以完成正常情况下难以在短时间内实施的城市空间改造、城市建设,以及将一些重要的政策尽早提上日程,城市采纳事件战略具有复杂的政治动机;3)大型事件的推动者往往是城市商业和政治精英结成的联盟,一方面他们共同致力于推动举办地的经济发展;另一方面他们也借此谋求政治及商业领域的社会资本;4)大型事件被用来作为合法化工具:是展示国家认同的合法化途径;获得公众支持的合法性;获得上一级政府支持,特别是资金支持的合法性;5)发展中国家,特别是非洲国家的申办更体现出其改善国际不平等关系及成为"非洲门户"的意愿。     

大功率高频X波欠密加热电离层的理论与数值模拟

基于电离层中电子的加热物理机制,构建了左旋圆极化(X波)欠密加热理论仿真模型,通过对已知实验的模拟验证了模型的正确性.并利用此模型分析和研究了不同加热参数和背景参数对X波欠密加热效果的影响,结果表明,在X波欠密加热中,加热效果随加热功率增加而增强,随加热频率增加而减弱,在相当的加热条件下,背景电子温度越低、电子密度越小,加热效果越强.最后简单分析了X波欠密加热的一些应用.     

Amplification of disturbances on a channel flow

Abstract

The stability of a rotating, stationary flow of zero potential vorticity in a slowly varying channel is examined using the method of multiple scales. This technique can be applied when the variations of the basic flow occur on a length scale which is much larger than the one associated with the perturbation. To lowest order the disturbance is described by a propagating part multiplied by a slowly changing amplitude. It is shown that when the phase speed of a disturbance approaches zero, the growth of the amplitude becomes unbounded. This happens when a perturbation superimposed upon a flow which is slightly sub/supercritical, or which alters from a super- to a subcritical state, propagates over a shoaling bottom. If, however, the change of the basic flow is from a sub- to a supercritical state, the phase speed is quite large and the amplitude of the perturbation will just show minor variations along the channel. The same holds true if the steady flow is only moderately affected by the changing topography. The problem has also been analyzed using wave-action formalism, and the outcome of this alternative approach to the stability problem proved to conform to the previously obtained results. Finally, an interpretation of the calculated growth rates is undertaken in terms of “convective” amplification and “absolute” instability.     

Coupling the 4M crop model with national geo-databases for assessing the effects of climate change on agro-ecological characteristics of Hungary

The 4M crop model was used to investigate the prospective effects of climate change on the agro-ecological characteristics of Hungary. The model was coupled with a detailed meteorological database and spatial soil information systems covering the whole territory of Hungary. Plant-specific model parameters were determined by inverse modeling. Future meteorological data were produced from the present meteorological data by combining a climate change scenario and a stochastic weather generator. Using the available and the generated data, the present and the prospective agro-ecological characteristics of Hungary were determined. According to the simulation results, average yields will decrease considerably (~30%) due to climate change. The rate of nitrate leaching will prospectively decrease as well. The fluctuations of both the yields and the annual nitrate leaching rates will most likely increase approaching the end of the twenty-first century. On the basis of the simulation results, the role of autumn crops is likely to become more significant in Hungary. The achieved results can be generalized for more extended regions based on the concept of spatial (geographical) analogy.