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51.
Georg Wohlfahrt Lukas Hrtnagl Albin Hammerle Martin Graus Armin Hansel 《Atmospheric environment (Oxford, England : 1994)》2009,43(30):4570-4576
Ozone (O3) fluxes above a temperate mountain grassland were measured by means of the eddy covariance (EC) method using a slow-response O3 analyser. The resultant flux loss was corrected for by a series of transfer functions which model the various sources of high- and, in particular, low-pass filtering. The resulting correction factors varied on average between 1.7 and 3.5 during night and daytime, respectively. A cospectral analysis confirmed the accuracy of this approach. O3 fluxes were characterised by a comparatively large random uncertainty, which during daytime typically amounted to 60%. EC O3 fluxes were compared against O3 flux measurements made concurrently with the flux-gradient (FG) method. The two methods generally agreed well, except for a period between sunrise and early afternoon, when the FG method was suspected of being affected by the presence of photochemical sources/sinks. O3 flux magnitudes and deposition velocities determined with the EC method compared nicely with the available literature from grassland studies. We conclude that our understanding of the causes and consequences of various sources of flux loss (associated with any EC system) has sufficiently matured so that also less-than-ideal instrumentation may be used in EC flux applications, albeit at the cost of relatively large empirical corrections. 相似文献
52.
Joshua K. Abbott James E. Wilen 《Journal of Environmental Economics and Management》2011,62(3):386-401
Much of the discussion of the tragedy of the commons focuses on aggregate impacts, often in data-poor developing country settings. Few non-experimental empirical studies shed light on contextual circumstances driving the extent of rent dissipation and overexploitation. We utilize a high-resolution data set to estimate a behavioral model of fishermen's spatial choices. A unique policy setting allows us to measure the degree to which individual fishermen's choices appear aimed at mitigating the tragedy of the commons in a small numbers setting. We find evidence of partial mitigation in excess of what we would expect under pure self-interest but short of what would occur under group-maximizing behavior. We also examine how contextual factors in the fishery shape the degree of cooperation within the fishing season and find evidence that competition for the common pool resource distorts fishermen's implicit cost of distance—creating a form of “common property inertia”. 相似文献
53.
Eric Bahel 《Journal of Environmental Economics and Management》2011,61(3):267-280
This paper studies the stockpiling issue for an oil importing country that is likely to suffer embargoes, the occurrence and duration of which are uncertain. I show the existence of a decreasing reserves path that the country wants to attain in order to hedge against these disruptions. Allowing the importing country to invest in R&D in order to free itself from the embargo threat, I determine the optimal effort that should be engaged in research. The incentive to develop a backstop is shown to increase with the depletion of the reserves. 相似文献
54.
《环境科学学报(英文版)》2023,35(4):506-516
Deterioration of surface ozone (O3) pollution in Northern China over the past few years received much attention. For many cities, it is still under debate whether the trend of surface O3 variation is driven by meteorology or the change in precursors emissions. In this work, a time series decomposition method (Seasonal-Trend decomposition procedure based on Loess (STL)) and random forest (RF) algorithm were utilized to quantify the meteorological impacts on the recorded O3 trend and identify the key meteorological factors affecting O3 pollution in Tianjin, the biggest coastal port city in Northern China. After “removing” the meteorological fluctuations from the observed O3 time series, we found that variation of O3 in Tianjin was largely driven by the changes in precursors emissions. The meteorology was unfavorable for O3 pollution in period of 2015-2016, and turned out to be favorable during 2017-2021. Specifically, meteorology contributed 9.3 µg/m3 O3 (13%) in 2019, together with the increase in precursors emissions, making 2019 to be the worst year of O3 pollution since 2015. Since then, the favorable effects of meteorology on O3 pollution tended to be weaker. Temperature was the most important factor affecting O3 level, followed by air humidity in O3 pollution season. In the midday of summer days, O3 pollution frequently exceeded the standard level (>160 µg/m3) at a combined condition with relative humidity in 40%-50% and temperature > 31°C. Both the temperature and the dryness of the atmosphere need to be subtly considered for summer O3 forecasting. 相似文献
55.
Kenneth A. Baerenklau Bill Provencher 《Journal of Environmental Economics and Management》2005,50(3):617-636
This paper examines the consequences of using a static model of recreation trip-taking behavior when the underlying decision problem is dynamic. Specifically we examine the implications for trip forecasting and welfare estimation using a panel dataset of Lake Michigan salmon anglers for the 1996 and 1997 fishing seasons. We derive and estimate both a structural dynamic model using Bellman's equation, and a reduced-form static model with trip probability expressions mimicking those of the dynamic model. We illustrate an inherent identification problem in the reduced-form model that creates biased welfare estimates, and we discuss the general implications of this for the interpretation of preference parameters in static models. We then use both models to simulate trip taking behavior and show that although their in-sample trip forecasts are similar, their welfare estimates and out-of-sample forecasts are quite different. 相似文献
56.
Introduction: Random Breath Testing (RBT) remains a primary method to both deter and apprehend drink drivers, yet a large proportion of road fatalities continue to be caused by the offense. Outstanding questions remain regarding how much exposure to RBT operations is needed to influence deterrence-based perceptions and subsequent offending. Method: Given this, licensed motorists (N = 961) in Queensland were recruited to complete a questionnaire either in the community (N = 741) or on the side of the road after just being breath tested (N = 243). Survey items measured different types of exposure to RBT operations (e.g., “seen” vs. “being tested”) and subsequent perceptions of apprehension as well as self-reported drink driving behaviors. Results: The key findings that emerged were: motorists were regularly exposed to RBT operations (both viewing and being tested), such exposure was not significantly correlated with perceptions of apprehension certainty, and a sizable proportion reported engaging in drink driving behaviors (e.g., approx. 25%), although roadside participants naturally reported a lower percentage of offending behaviors. Importantly, it was revealed that current “observations” of RBT was sufficient, but not actual levels of active testing (which needed to be doubled). Nevertheless, higher levels of exposure to RBT operations was found to be predictive of a lack of intention to drink and drive again in the future. Conclusions: This paper suggests that mere exposure to enforcement may not create the intended rule compliance, and that the frequency of exposure is also essential for the roadside. 相似文献
57.
58.
Quantifying dispersal is crucial both for understanding ecological population dynamics, and for gaining insight into factors that affect the genetic structure of populations. The role of dispersal becomes pronounced in highly fragmented landscapes inhabited by spatially structured populations. We consider a landscape consisting of a set of habitat patches surrounded by unsuitable matrix, and model dispersal by assuming that the individuals follow a random walk with parameters that may be specific to the habitat type. We allow for spatial variation in patch quality, and account for edge-mediated behavior, the latter meaning that the individuals bias their movement towards the patches when close to an edge between a patch and the matrix. We employ a diffusion approximation of the random walk model to derive analytical expressions for various characteristics of the dispersal process. For example, we derive formulae for the time that an individual is expected to spend in its current patch i, and for the time that it will spend in the matrix, both conditional on the individual hitting next a given patch j before hitting any of the other patches or dying. The analytical formulae are based on the assumptions that the landscape is infinitely large, that the patches are circularly shaped, and that the patches are small compared to interpatch distances. We evaluate the effect of these assumptions by comparing the analytical results to numerical results in a real patch network that violates all of the three assumptions. We then consider a landscape that fulfills the assumptions, and show that in this case the analytical results are in a very good agreement with the numerical results. The results obtained here allow the construction of computationally efficient dispersal models that can be used as components of metapopulation models. 相似文献
59.
B. Gail Ivanoff 《Environmental and Ecological Statistics》2009,16(2):153-171
The concept of the renewal property is extended to processes indexed by a multidimensional time parameter. The definition
given includes not only partial sum processes, but also Poisson processes and many other point processes whose jump points
are not totally ordered. Various properties of renewal processes are discussed. Renewal processes are proposed as a basis
for modelling the spread of a forest fire under a prevailing wind.
相似文献
B. Gail IvanoffEmail: |
60.
本文简述运输环境和试验条件的制订对模拟运输试验的各种方法作了简单评述,尤其是对利用电子--液压振动台对大型整体产品在悬臂梁状态的试验作了介绍。最后说明一种能模拟带有高峰值随机振动的试验技术,以改进现有数控设备的不足。 相似文献