643 research outputs found

    Integrated planning framework for successful river restoration projects: upscaling lessons learnt from European case studies

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    Despite considerable investment in river restoration projects, there is still limited information on the efficacy and success of river restoration activities. One of the main reasons is poor or improper project design, resulting in common problems such as: not addressing the root cause of habitat degradation; not establishing reference conditions, benchmarks and not defining endpoints against which to measure success; inappropriate uses of common restoration techniques because of lack of pre-planning; and inadequate monitoring or appraisal of restoration projects. In this paper peer-reviewed and grey literature and a large database of existing case studies were reviewed to identify the prevailing challenges river managers face when planning and developing river restoration projects. To overcome these current challe nges an integrated project planning framework has been developed that incorporates adaptive management and project management techniques. It encapsulates key concepts and decision support tools to advance the existing sequence of project identification, project formulation, project implementation and post-project monitoring to incorporate multidisciplinary decision making to meet specific environmental and socio-economic objectives. The proposed river restoration project planning framework is adaptable and can therefore be applied to any project development scenario locally, regionally or internationally

    First Observations of a Foreshock Bubble at Earth: Implications for Magnetospheric Activity and Energetic Particle Acceleration

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    Earth?s foreshock, which is the quasi-parallel region upstream of the bow shock, is a unique plasma region capable of generating several kinds of large-scale phenomena, each of which can impact the magnetosphere resulting in global effects. Interestingly, such phenomena have also been observed at planetary foreshocks throughout our solar system. Recently, a new type of foreshock phenomena has been predicted: foreshock bubbles, which are large-scale disruptions of both the foreshock and incident solar wind plasmas that can result in global magnetospheric disturbances. Here we present unprecedented, multi-point observations of foreshock bubbles at Earth using a combination of spacecraft and ground observations primarily from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission, and we include detailed analysis of the events? global effects on the magnetosphere and the energetic ions and electrons accelerated by them, potentially by a combination of first and second order Fermi and shock drift acceleration processes. This new phenomena should play a role in energetic particle acceleration at collisionless, quasi-parallel shocks throughout the Universe

    Structure, classifcation, and conformal symmetry, of elementary particles over non-archimedean space-time

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    It is known that no length or time measurements are possible in sub-Planckian regions of spacetime. The Volovich hypothesis postulates that the micro-geometry of spacetime may therefore be assumed to be non-archimedean. In this letter, the consequences of this hypothesis for the structure, classification, and conformal symmetry of elementary particles, when spacetime is a flat space over a non-archimedean field such as the pp-adic numbers, is explored. Both the Poincar\'e and Galilean groups are treated. The results are based on a new variant of the Mackey machine for projective unitary representations of semidirect product groups which are locally compact and second countable. Conformal spacetime is constructed over pp-adic fields and the impossibility of conformal symmetry of massive and eventually massive particles is proved

    The space physics environment data analysis system (SPEDAS)

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    With the advent of the Heliophysics/Geospace System Observatory (H/GSO), a complement of multi-spacecraft missions and ground-based observatories to study the space environment, data retrieval, analysis, and visualization of space physics data can be daunting. The Space Physics Environment Data Analysis System (SPEDAS), a grass-roots software development platform (www.spedas.org), is now officially supported by NASA Heliophysics as part of its data environment infrastructure. It serves more than a dozen space missions and ground observatories and can integrate the full complement of past and upcoming space physics missions with minimal resources, following clear, simple, and well-proven guidelines. Free, modular and configurable to the needs of individual missions, it works in both command-line (ideal for experienced users) and Graphical User Interface (GUI) mode (reducing the learning curve for first-time users). Both options have “crib-sheets,” user-command sequences in ASCII format that can facilitate record-and-repeat actions, especially for complex operations and plotting. Crib-sheets enhance scientific interactions, as users can move rapidly and accurately from exchanges of technical information on data processing to efficient discussions regarding data interpretation and science. SPEDAS can readily query and ingest all International Solar Terrestrial Physics (ISTP)-compatible products from the Space Physics Data Facility (SPDF), enabling access to a vast collection of historic and current mission data. The planned incorporation of Heliophysics Application Programmer’s Interface (HAPI) standards will facilitate data ingestion from distributed datasets that adhere to these standards. Although SPEDAS is currently Interactive Data Language (IDL)-based (and interfaces to Java-based tools such as Autoplot), efforts are under-way to expand it further to work with python (first as an interface tool and potentially even receiving an under-the-hood replacement). We review the SPEDAS development history, goals, and current implementation. We explain its “modes of use” with examples geared for users and outline its technical implementation and requirements with software developers in mind. We also describe SPEDAS personnel and software management, interfaces with other organizations, resources and support structure available to the community, and future development plans.Published versio

    Survey of the ULF wave Poynting vector near the Earth's magnetic equatorial plane

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/101878/1/pdfexplain.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/101878/2/jgra50591.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/101878/3/pdfexplain.tx

    On the cause and extent of outer radiation belt losses during the 30 September 2012 dropout event

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    Abstract On 30 September 2012, a flux dropout occurred throughout Earth\u27s outer electron radiation belt during the main phase of a strong geomagnetic storm. Using eight spacecraft from NASA\u27s Time History of Events and Macroscale Interactions during Substorms (THEMIS) and Van Allen Probes missions and NOAA\u27s Geostationary Operational Environmental Satellites constellation, we examined the full extent and timescales of the dropout based on particle energy, equatorial pitch angle, radial distance, and species. We calculated phase space densities of relativistic electrons, in adiabatic invariant coordinates, which revealed that loss processes during the dropout were \u3e 90% effective throughout the majority of the outer belt and the plasmapause played a key role in limiting the spatial extent of the dropout. THEMIS and the Van Allen Probes observed telltale signatures of loss due to magnetopause shadowing and subsequent outward radial transport, including similar loss of energetic ring current ions. However, Van Allen Probes observations suggest that another loss process played a role for multi-MeV electrons at lower L shells (L\u3c ∼4). Key Points Dropout events can encompass the entire outer radiation belt Dropouts can result in \u3e90% losses and be a hard reset on the system Loss at L \u3e ∼4 is dominated by MP shadowing and outward transport

    Global properties of magnetotail current sheet flapping: THEMIS perspectives

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    A sequence of magnetic field oscillations with an amplitude of up to 30 nT and a time scale of 30 min was detected by four of the five THEMIS spacecraft in the magnetotail plasma sheet. The probes P1 and P2 were at <I>X</I>=−15.2 and −12.7 <I>R<sub>E</sub></I> and P3 and P4 were at <I>X</I>=−7.9 <I>R<sub>E</sub></I>. All four probes were at −6.5><I>Y</I>>−7.5 <I>R<sub>E</sub></I> (major conjunction). Multi-point timing analysis of the magnetic field variations shows that fronts of the oscillations propagated flankward (dawnward and Earthward) nearly perpendicular to the direction of the magnetic maximum variation (<I>B</I><sub>1</sub>) at velocities of 20–30 km/s. These are typical characteristics of current sheet flapping motion. The observed anti-correlation between ∂<I>B</I><sub>1</sub>/∂<I>t</I> and the Z-component of the bulk velocity make it possible to estimate a flapping amplitude of 1 to 3 <I>R<sub>E</sub></I>. The cross-tail scale wave-length was found to be about 5 <I>R<sub>E</sub></I>. Thus the flapping waves are steep tail-aligned structures with a lengthwise scale of >10 <I>R<sub>E</sub></I>. The intermittent plasma motion with the cross-tail velocity component changing its sign, observed during flapping, indicates that the flapping waves were propagating through the ambient plasma. Simultaneous observations of the magnetic field variations by THEMIS ground-based magnetometers show that the flapping oscillations were observed during the growth phase of a substorm
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