Data‐driven modelling of shortwave radiation transfer to snow through boreal birch and conifer canopies          下载免费PDF全文

T. D. Reid  R. L. H. Essery  N. Rutter  M. King 《水文研究》2014,28(6):2987-3007

Hydrological and land surface models require simple but accurate methods to predict the solar radiation transmitted through vegetation to snow, backed up by direct comparisons to data. Twenty shortwave pyranometers were deployed in forest plots of varying canopy structures and densities in sparse birch forest near Abisko, Sweden, in spring 2011 and mixed conifer forest near Sodankylä, Finland, in spring 2012. Above‐canopy global and diffuse shortwave irradiances were also measured. These data were used to test a model that uses hemispherical photographs to explicitly estimate both diffuse radiation and direct beam transmission, as well as two models that apply bulk canopy parameters and versions of Beers Law. All three models predict canopy shortwave transmission similarly well for leafless birch forest, but for conifers, the bulk methods perform poorly. In addition, an existing model of multiple reflections between canopy and snow was found to be suitable for birch, but not conifers. A new bulk approach based on empirical relationships with hemisphere‐averaged sky view fraction showed improved performance for both sites; this suggests benefits of avoiding the use of plant area index calculated from optical methods, which can introduce errors. Furthermore, tests using common empirical diffuse radiation models were shown to underestimate shortwave transmission by up to 7% relative to using the data, suggesting that new diffuse models are required for high latitudes. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

'Green' enclosure of ocean space--déjà vu?     

Sand PH 《Marine pollution bulletin》2007,54(4):374-376

The first wave of unilaterally declared environmental protection zones (starting with Canada's Arctic Waters Pollution Prevention Act of 1970) may have been halted by the 1982 UN Convention on the Law of the Sea. Yet, a second wave now seems to be gaining momentum: the French 'ecological protection zone in the Mediterranean' of April 2003 (promptly emulated by Croatia, Slovenia, and Italy), the British 'environment (protection and preservation) zone' around the Chagos Archipelago of September 2003, and the US 'marine national monument' around the Northwestern Hawaiian Islands of June 2006, all claiming new environmental regulatory powers in sea areas way beyond territorial waters. This viewpoint article questions the unilateral legitimation of those claims, and postulates a trusteeship ethos and fiduciary accountability for ocean governance in these areas.  相似文献   

Maximum magnitudes in aftershock sequences in Taiwan     

《Journal of Asian Earth Sciences》2013

In this work, Båth’s Law, the b-value in Gutenberg–Richter Law (G–R Law) in the form of the 1/β relationship, and both the a- and b-values in the G–R Law were introduced in order to estimate maximum aftershock magnitudes of earthquake sequences in the Taiwan region. The averaged difference of magnitude between the mainshock and the maximum aftershock is 1.20, and is consistent with Båth’s Law, however, with a large uncertainty. The large uncertainty implies that the difference may result from a variable controlled by other factors, such as the aftershocks number of an earthquake sequence and magnitude threshold for mainshock. With 1/β, since 86% of the earthquake sequences with a M ⩾ 6.0 mainshock follow this relationship, the upper bound of the maximum magnitude can be estimated for an earthquake sequence with a large mainshock. The a- and b-values in the G–R Law was also considered by evaluating maximum aftershock magnitudes. As there are low residuals between the model and the observations, the results suggest that the G–R Law is a good index for maximum aftershock magnitude determinations. In order to evaluate the temporal decays of maximum aftershock magnitudes, modified Omori’s Law was introduced. Using the approaches mentioned above, the maximum magnitudes and the temporal evolution of an earthquake sequence could be modeled. Among them, the model of the G–R Law has the best fit with observations for most of earthquake sequences. It shows its feasibility. The results of this work may benefit seismic hazards mitigation in the form of rapid re-evaluations for short-term seismic hazards immediately following devastating earthquakes.  相似文献   

XXIII INTERNATIONAL GEOGRAPHICAL CONGRESS,U.S.S.R.     

《The Professional geographer》2013,65(3):296-297

Edward Jarvis in 1850 first demonstrated that admission rates to mental hospitals decrease with increasing residential distance, a relationship known today as “Jarvis's Law.” His original data are presented, mapped, and examined by regression analysis to better understand spatial and temporal patterns of mid-19th century mental hospital utilization. Distance substantially affected admission rates to a radius of about 60 miles from the institution in Massachusetts; and there was strong distance decay in the other states examined. For all twelve states, there was a positive association between age of the hospitals and admission rates, which also decreased with increasing residential distance.  相似文献   

论渔业法之对影响渔业船舶适航行为的法律责任          下载免费PDF全文

张安琪  裴兆斌 《海洋开发与管理》2020,37(9):31-34

渔船管理是渔业产业管理的重要内容，而船舶适航性是渔船正常运行的重要保证。我国现阶段渔业产业中出现的船舶事故频发，其中很多是不适航导致的。文章从我国渔业监管现状出发，结合《渔业法》及其相关法律对影响船舶适航行为法律责任的相关规定，分析违法行为构成要件，发现依然存在处罚手段单一、处罚力度不够等问题，针对存在的原因，从完善对相关违法行为的认定，加强行政监管，丰富处罚方式，提高行政处罚标准等措施出发提出完善建议，从而减少渔业安全事故，推动我国渔业健康发展。  相似文献   

九段沙湿地自然保护区执法模式初探     

孙瑛  张泰 《湿地科学与管理》2010,6(4):38-41

湿地执法管理是湿地保护的重要手段,探讨了九段沙湿地执法管理的3种模式:单一执法、联合执法、综合执法。根据九段沙湿地现状,认为综合执法是九段沙湿地保护和管理的最佳模式,它将为上海市的国际化生态城市的建设和经济的可持续发展起到积极作用。  相似文献   

浅论促进地理信息产业健康发展的法治保障     

王保立 《地理信息世界》2013,(2)

推进测绘地理信息依法行政对于促进地理信息产业健康发展具有保驾护航的重要作用.本文概述了我国测绘地理信息市场的发展形势,分析了制约地理信息产业健康发展所面临的主要问题和挑战,提出了规范市场秩序、优化发展环境的重点任务和促进地理信息产业做大做强的保障服务措施.  相似文献   

Eliminating illegal bottom trawl fishing in the coastal waters of Korea     

Dong-Oh Cho 《Marine Policy》2012,36(2):321-326

Illegal bottom trawl fishing using nets with a small mesh size has been one of the most difficult problems to address in fisheries management in Korea. This practice has occurred for the last century, since the Japanese colonial period. The elimination of illegal bottom trawl fishing, regulated in the Fisheries Law (Law No. 10292), was extremely difficult because the number of vessel owners increased to greater than 3000, creating a strong oppositional lobby. Therefore, the Korean government carried out an ‘incentive program’ to buy-back vessels, which has been very effective in eliminating illegal bottom trawl fishing in the coastal waters of Korea.  相似文献   

金乡县土地执法监察中存在的问题及对策     

李国安 《山东国土资源》2012,28(11):68-69,72

随着经济的快速发展和城市化进程的日趋加快,金乡县用地需求不断加大,供需矛盾越来越尖锐。为保护耕地资源,保障经济发展,金乡县国土资源局以科学的发展观为指导,明确工作目标,更新执法理念,创新执法机制,强化执法手段,提高了国土资源执法监察水平,取得明显成效。  相似文献   

Variable and conflicting shear stress estimates inside a boundary layer with sediment transport          下载免费PDF全文

Zoë S. Lee  Andreas C. W. Baas 《地球表面变化过程与地形》2016,41(4):435-445

This paper presents a comparison between two methods for estimating shear stress in an atmospheric internal boundary layer over a beach surface under optimum conditions, using wind velocities measured synchronously at 13 heights over a 1.7 m vertical array using ultrasonic anemometry. The Reynolds decomposition technique determines at‐a‐point shear stresses at each measurement height, while the Law‐of‐the‐Wall yields a single boundary layer estimate based on fitting a logarithmic velocity profile through the array data. Analysis reveals significant inconsistencies between estimates derived from the two methods, on both a whole‐event basis and as time‐series. Despite a near‐perfect fit of the Law‐of‐the‐Wall, the point estimates of Reynolds shear stress vary greatly between heights, calling into question the assumed presence of a constant stress layer. A comparison with simultaneously measured sediment transport finds no relationship between transport activity and the discrepancies in shear stress estimates. Results do show, however, that Reynolds shear stress measured nearer the bed exhibits slightly better correlation with sand transport rate. The findings serve as a major cautionary message to the interpretation and application of single‐height measurements of Reynolds shear stress and their equivalence to Law‐of‐the‐Wall derived estimates, and these concerns apply widely to boundary layer flows in general. © 2015 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.  相似文献