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51.
52.
Digital technologies, including participatory Internet mapping, social media and smartphones, provide new avenues for research in outdoor recreation and tourism. The potential to reach a greater audience and collect visitation data on a broader scale, with less costs than traditional paper surveys, are key advantages that have increased the use of these novel technologies. Using of mobile apps for data collection is still at the experimental stage. We evaluate previous attempts to use apps for monitoring recreation and tourism in protected areas, as an alternative to other in situ or online methods. We present a pilot study implemented in Jotunheimen National Park (Norway), where we developed a mobile app for visitor monitoring and real-time mapping of values and experiences. We present the lessons learned, give suggestions on how and for what apps can be used, and discuss the advantages and limitations of using smartphones for visitor monitoring in protected areas. 相似文献
53.
Elimination of the water-layer response from multi-component source and receiver marine electromagnetic data 总被引:1,自引:0,他引:1
Janniche Iren Nordskag Lasse Amundsen Lars Løseth Egil Holvik 《Geophysical Prospecting》2009,57(5):897-918
This paper presents the theory to eliminate from the recorded multi‐component source, multi‐component receiver marine electromagnetic measurements the effect of the physical source radiation pattern and the scattering response of the water‐layer. The multi‐component sources are assumed to be orthogonally aligned above the receivers at the seabottom. Other than the position of the sources, no source characteristics are required. The integral equation method, which for short is denoted by Lorentz water‐layer elimination, follows from Lorentz' reciprocity theorem. It requires information only of the electromagnetic parameters at the receiver level to decompose the electromagnetic measurements into upgoing and downgoing constituents. Lorentz water‐layer elimination replaces the water layer with a homogeneous half‐space with properties equal to those of the sea‐bed. The source is redatumed to the receiver depth. When the subsurface is arbitrary anisotropic but horizontally layered, the Lorentz water‐layer elimination scheme greatly simplifies and can be implemented as deterministic multi‐component source, multi‐component receiver multidimensional deconvolution of common source gathers. The Lorentz deconvolved data can be further decomposed into scattering responses that would be recorded from idealized transverse electric and transverse magnetic mode sources and receivers. This combined electromagnetic field decomposition on the source and receiver side gives data equivalent to data from a hypothetical survey with the water‐layer absent, with idealized single component transverse electric and transverse magnetic mode sources and idealized single component transverse electric and transverse magnetic mode receivers. When the subsurface is isotropic or transverse isotropic and horizontally layered, the Lorentz deconvolution decouples into pure transverse electric and transverse magnetic mode data processing problems, where a scalar field formulation of the multidimensional Lorentz deconvolution is sufficient. In this case single‐component source data are sufficient to eliminate the water‐layer effect. We demonstrate the Lorentz deconvolution by using numerically modeled data over a simple isotropic layered model illustrating controlled‐source electromagnetic hydrocarbon exploration. In shallow water there is a decrease in controlled‐source electromagnetic sensitivity to thin resistors at depth. The Lorentz deconvolution scheme is designed to overcome this effect by eliminating the water‐layer scattering, including the field's interaction with air. 相似文献
54.
Anders Ruus Norman W. Green Carl Einar Amundsen Jens Skei 《Marine pollution bulletin》2010,60(10):1856-1861
The Sørfjord has a long history of agriculture and industry, and environmental monitoring has been conducted for decades, comprising analyses of contaminants in mussel, fish and sediments. DDT was used as an insecticide in orchards surrounding the fjord between World War II and 1970. Since the early 1990s, elevated concentrations of DDT were found in mussels and fish. Unexpectedly, DDT-concentrations increased towards present day, despite the discontinuation of use. The highest concentrations in mussels (in 2006) corresponded to about two orders of magnitude higher than background. Analyses of sediment core sections also indicated increased input towards present day. Shifts in climatic parameters, as well as increased amounts of soil dissolved organic carbon following a decline in atmospheric sulphate deposition may have contributed to this phenomenon. We warrant the need for increased knowledge of the effects of alterations in variables acting regionally and globally on the disposition of contaminants in ecosystems. 相似文献
55.
Jens Wittsten Fredrik Andersson Johan Robertsson Lasse Amundsen 《Geophysical Prospecting》2019,67(6):1486-1497
A major focus of research in the seismic industry of the past two decades has been the acquisition and subsequent separation of seismic data using multiple sources fired simultaneously. The recently introduced method of signal apparition provides a new take on the problem by replacing the random time-shifts usually employed to encode the different sources by fully deterministic periodic time-shifts. In this paper, we give a mathematical proof showing that the signal apparition method results in optimally large regions in the frequency–wavenumber space where exact separation of sources is achieved. These regions are diamond shaped and we prove that using any other method of source encoding results in strictly smaller regions of exact separation. The results are valid for arbitrary number of sources. Numerical examples for different number of sources (three, respectively, four sources) demonstrate the exact recovery of these diamond-shaped regions. The implementation of the theoretical proofs in the field is illustrated by the results of a conducted field test. 相似文献
56.
Hans‐Eike Gäbler Frank Melcher Torsten Graupner Andreas Bahr Maria A. Sitnikova Friedhelm Henjes‐Kunst Thomas Oberthür Helene Brätz Axel Gerdes 《Geostandards and Geoanalytical Research》2011,35(4):431-448
Coltan (the African trade name for columbite‐tantalite, a tantalum ore) is one of several raw materials that finance the civil wars in the eastern provinces of the Democratic Republic of the Congo. To improve the transparency along the tantalum trade chain, a ‘certificate of origin’ for so‐called ‘conflict minerals’ has been recommended by the United Nations. Accordingly, the German Federal Institute for Geosciences and Natural Resources (BGR) has developed an analytical fingerprint procedure for coltan. Mineral formation age, modal mineralogy and chemical composition are important fingerprint parameters. The original workflow to obtain these parameters was streamlined and is now based on mineral liberation analysis and LA‐ICP‐MS. The use of an ICP‐MS instrument with a detector system covering an extended linear dynamic range and the application of an internal standard‐independent calibration strategy allowed data for major and trace element determination and mineral formation age estimates to be obtained simultaneously. The analytical results of this new approach were compared with analytical techniques of the original workflow and showed excellent agreement in terms of mineralogical and chemical characterisation and mineral formation age of coltan samples. Within a test, samples of different origin were allocated correctly and simple, binary mixtures were also identified successfully. 相似文献
57.
Ingrid Marie Hasle Amundsen Maria Blinova Berit Oline Hjelstuen Rolf Mjelde Haflidi Haflidason 《Marine Geophysical Researches》2011,32(4):441-453
The northeastern high-latitude North Atlantic is characterised by the Bellsund and Isfjorden fans on the continental slope
off west Svalbard, the asymmetrical ultraslow Knipovich spreading ridge and a 1,000 m deep rift valley. Recently collected
multichannel seismic profiles and bathymetric records now provide a more complete picture of sedimentary processes and depositional
environments within this region. Both downslope and alongslope sedimentary processes are identified in the study area. Turbidity
currents and deposition of glacigenic debris flows are the dominating downslope processes, whereas mass failures, which are
a common process on glaciated margins, appear to have been less significant. The slide debrite observed on the Bellsund Fan
is most likely related to a 2.5–1.7 Ma old failure on the northwestern Barents Sea margin. The seismic records further reveal
that alongslope current processes played a major role in shaping the sediment packages in the study area. Within the Knipovich
rift valley and at the western rift flank accumulations as thick as 950–1,000 m are deposited. We note that oceanic basement
is locally exposed within the rift valley, and that seismostratigraphic relationships indicate that fault activity along the
eastern rift flank lasted until at least as recently as 1.5 Ma. A purely hemipelagic origin of the sediments in the rift valley
and on the western rift flank is unlikely. We suggest that these sediments, partly, have been sourced from the western Svalbard—northwestern
Barents Sea margin and into the Knipovich Ridge rift valley before continuous spreading and tectonic activity caused the sediments
to be transported out of the valley and westward. 相似文献
58.
59.
Kristen Weiss Mark Hamann Michael Kinney Helene Marsh 《Global Environmental Change》2012,22(1):178-188
Few case studies have considered the impact of network structure on the resilience of complex resource management systems that operate over large spatial scales. To help fill this knowledge gap our study examined two types of relational ties—knowledge exchange and policy influence—within a marine wildlife co-management network in Northern Australia. We conducted interviews and follow-up surveys with key-informant stakeholders in dugong and marine turtle management and used these data to perform social network analysis for the dugong and turtle co-management network. The network structure of this marine governance system supports extensive cross-scale information flow, but with a disproportionate amount of top-down policy influence compared with knowledge accumulation, an arrangement that may hinder evidence-based decision making. We developed a typological ‘map’ of stakeholder roles in the network to characterize each stakeholder's contribution of knowledge and ability to influence policy, helping to identify gaps or overlaps in network linkages. Improving communication links between knowledge producers and policy makers is important for evidence based decision making throughout the management network, while addressing overlapping management roles and functions should help decrease conflict in the system. These improvements would increase social-ecological resilience in the management network by providing better protection for marine species while meeting the needs of diverse stakeholders. 相似文献
60.
This paper aims at characterizing how different key cloud properties (cloud fraction, cloud vertical distribution, cloud reflectance, a surrogate of the cloud optical depth) vary as a function of the others over the tropical oceans. The correlations between the different cloud properties are built from 2?years of collocated A-train observations (CALIPSO-GOCCP and MODIS) at a scale close to cloud processes; it results in a characterization of the physical processes in tropical clouds, that can be used to better understand cloud behaviors, and constitute a powerful tool to develop and evaluate cloud parameterizations in climate models. First, we examine a case study of shallow cumulus cloud observed simultaneously by the two sensors (CALIPSO, MODIS), and develop a methodology that allows to build global scale statistics by keeping the separation between clear and cloudy areas at the pixel level (250, 330?m). Then we build statistical instantaneous relationships between the cloud cover, the cloud vertical distribution and the cloud reflectance. The vertical cloud distribution indicates that the optically thin clouds (optical thickness <1.5) dominate the boundary layer over the trade wind regions. Optically thick clouds (optical thickness >3.4) are composed of high and mid-level clouds associated with deep convection along the ITCZ and SPCZ and over the warm pool, and by stratocumulus low level clouds located along the East coast of tropical oceans. The cloud properties are analyzed as a function of the large scale circulation regime. Optically thick high clouds are dominant in convective regions (CF?>?80?%), while low level clouds with low optical thickness (<3.5) are present in regimes of subsidence but in convective regimes as well, associated principally to low cloud fractions (CF?<?50?%). A focus on low-level clouds allows us to quantify how the cloud optical depth increases with cloud top altitude and with cloud fraction. 相似文献