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81.
Temporal variability of diverse mountain permafrost slope movements derived from multi-year daily GPS data,Mattertal, Switzerland 总被引：1，自引：0，他引：1
In this study, high resolution surface measurements of diverse slope movements are compared to environmental factors such as ground surface temperature (GST) and snow cover, in order to reveal and compare velocity fluctuations caused by changing environmental conditions. The data cover 2 years (2011–2013) of Global Positioning System (GPS) and GST measurements at 18 locations on various slope movement types within an alpine study site in permafrost (Mattertal, Switzerland). Velocities have been estimated based on accurate daily GPS solutions. The mean annual velocities (MAV) observed at all GPS stations varied between 0.006 and 6.3 ma?1. MAV were higher in the period 2013 compared to 2012 at all stations. The acceleration in 2013 was accompanied by a longer duration of the snow cover and zero curtain and slightly lower GST. The amplitude (0–600 %) and the timing of the intra-annual variability were generally similar in both periods. At most stations, an annual cycle in the movement signal was observed, with a phase lag of 1–4 months to GST. Maximum velocity typically occurred in late summer and autumn, and minimum velocity in late winter and beginning of spring. The onset of acceleration always started in spring during the snowmelt period. At two stations located on steep rock glacier tongues, overprinted on the annual cycle, short-term peaks of velocity increase, occurred during the snowmelt period, indicating a strong influence of meltwater. 相似文献
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84.
William Gladstone Nicole Hacking Vanessa Owen 《Estuarine, Coastal and Shelf Science》2006,67(4):708-720
Intermittently opening estuaries are artificially opened to manage flood risk, water quality, recreational amenity, and fisheries; however, the ecological impacts of this management technique are incompletely understood. During 2001 and 2004, this study assessed the impacts of artificial openings on the macroinvertebrates of entrance barriers of intermittently opening estuaries in New South Wales (Australia). In 2001 macroinvertebrates were sampled once before artificial opening and 9 and 25 d after re-formation of the entrance barrier. A multiple before–after-control-impact analysis found that, although entrance barriers were destroyed by the artificial openings and then re-formed naturally by wave action, significant interactions for taxonomic richness, density of the amphipod Paracalliope australis (Gammaridae) and density of the gastropod mollusc Aschoris victoriae (Hydrobiidae) meant that the effects of this disturbance could not be distinguished from the natural variations that occurred in unopened estuaries. Multivariate analyses found that assemblages at both opened and unopened estuaries changed from before to after the openings, and the magnitude of the dissimilarity between times varied between estuaries. In 2004, macroinvertebrates were sampled on three randomly selected days within each of three periods (before, 3 d and 42 d after) at one opened and three unopened estuaries. Asymmetrical analysis of this modified before–after-control-impact study found that the change in taxonomic richness at the opened estuary from before to after opening did not differ from temporal changes that occurred in unopened estuaries. Short-term variation (i.e. between days) in total density of macroinvertebrates and density of P. australis in the re-formed entrance barrier of the opened estuary also did not differ from the variation in the control estuaries. Additionally, assemblage structure was not significantly changed by the opening and assemblages at two control estuaries were also unchanged over the same time. Individual taxa and assemblages of macroinvertebrates in entrance barriers of these intermittently open estuarine systems appear to be resilient to the habitat disturbance caused by artificial openings. 相似文献
85.
Climate policy across the world is proceeding at a highly variable pace, with some places very committed to decarbonizing their economies and others just beginning. Emerging nations are generally just starting along this journey. However, among the few nation states that have pledged to achieve carbon neutrality, is Bhutan, a least developed country. Carbon neutrality is an ambitious climate policy that is increasingly being recognized as necessary in order to stabilize global temperature rise at 1.5°C. However, Bhutan is likely to face significant challenges in maintaining this status as the country balances its desire to grow in economic opportunities (GDP) and in human happiness (GNH). Little research has been conducted inside the policy processes to better understand how Bhutan will maintain carbon neutrality. Through open-ended, semi-structured interviews with key stakeholders, this study provides an inside view on the current situation and future challenges that Bhutan may face, along with the complexities associated with implementing and maintaining an ambitious carbon neutral policy. The paper highlights Bhutan's story and how it could be useful for policy learning and knowledge sharing, especially in the context of emerging nations’ climate governance. 相似文献
86.
One of the most significant impacts of the United Nations Framework Convention on Climate Change (UNFCCC) has been the establishment of a participatory process for Reducing Emissions from Deforestation and Forest Degradation (REDD+). We analyse the case of Brazil, the country whose land-use emissions from deforestation and forest degradation have declined the most. Through semi-structured interviews with 29 country policy experts – analysed in full text around 7 categories of activities that existing literature identifies as central elements of an effective governance system – we find weak links between the international REDD+ system and what actually happens on the ground inside Brazil. The greatest weaknesses are rooted in the absence of any formal learning system, which prevents higher-level efforts from obtaining useful feedback from lower-level entities responsible for implementation. Analytically our approach is rooted in the idea of ‘experimentalist governance’ in which local policy experiments map the space of what is possible and effective with transformative land policy. These experiments provide information to broader international initiatives on how local implementation shapes the ability and strategy to reach global goals. The Brazilian experience suggests that even when international funding is substantial, local implementation remains a weak link. REDD+ reforms should focus less on the total amount of money being spent and much more on how those funds are used to generate useful local policy experiments and learning.
Key policy insights
A nascent system of experimentalist governance to implement REDD+ is taking shape in Brazil. However, the potential for experimentalism to improve policy reforms within Brazil is far from realized;
Experimentalist problem-solving approaches could have a big impact on REDD+ with stronger incentives to promote experimentation and learning from experience;
Reforms to REDD+ incentive schemes should focus less on the total amount of money being spent and more on whether those funds are actually generating experimental learning and policy improvement – in Brazil and in other countries struggling with similar challenges.
87.
Ocean Dynamics - Understanding the processes that lead to seasonal changes in grain size on muddy macro-tidal flat and channel complexes will assist efforts to predict future changes caused by... 相似文献
88.
Drumond David Alvarenga Amarante Flávio Azevedo Neves Koppe Vanessa Cerqueira Costa João Felipe Coimbra Leite 《Natural Resources Research》2020,29(1):551-560
Natural Resources Research - Resources of mineral deposits are commonly estimated using data extracted from rock cores obtained by drilling. Information of good quality and quantity is essential to... 相似文献
89.
Vanessa Lamb 《Singapore journal of tropical geography》2019,40(2):338-341
90.
Francisco Barros Vanessa Hatje Maria Betnia Figueiredo Wagner Ferreira Magalhes Haroldo Silveira Drea Elissandro Soares Emídio 《Estuarine, Coastal and Shelf Science》2008,78(4):753-762
The structure of the benthic macrofaunal assemblages of the estuarine portion of Paraguaçu River, NE, Brazil, and its relationship with surface sediment characteristics (trace metals, PAHs, nutrients and grain size) and physical variables were investigated at ten stations on two contrasting occasions, summer (dry season) and winter (rainy season). A total of 1258 individuals (632 in winter and 626 in summer) and 62 taxa representing polychaetes, crustaceans, bivalves, echinoderms, bryozoans, sponges, cnidarians and cephalochordates were collected. Benthic assemblages in the upper estuary were unlike those in the lower estuary and a clear substitution of benthic taxa along the estuary was observed. Macrofaunal invertebrates in the low salinity region, composed of coarse sediments, were dominated by tellinids, venerids (bivalves), cirolanids (isopods), cyclopoids (copepods), and nereidids (polychaetes). While the high salinity region, composed of fine sediments, were dominated by nuculids (bivalves), cirratulids (polychaetes), and by amphiurids (ophiuroids). The Paraguaçu estuarine system is not severely affected by anthropogenic activities. In the great majority of the study sites, concentrations of trace metals and PAHs in the sediments were near background values. Nutrients values were also low. We formulated new models of taxon distribution and suggested detailed studies on the effects of salinity variation and studies using functional approaches to better understand the processes causing the spatial patterns in tropical estuarine benthic assemblages. 相似文献