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  • 1
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    International activities in HF sky-wave field-strength estimation (period 1956-1991) (2006)
    Details
    Publication Date: 2019-11-04
    Description: Methods for the determination of the strengths of radio signals reflected from the ionosphere and propagated to distant locations are required for service planning and circuit operation. Efforts are described following World War II to arrive at agreed procedures and some of the features of the various empirical prediction methods that have been formulated over the years are discussed. The problems are highlighted of determining a "best" method from among those available. Measurement data collected for this purpose are reviewed and attention is drawn to their limitations of accuracy and coverage. Even comparison of predicted and measured values is not straightforward, and the techniques that have been developed to do this are considered.
    Description: JCR Journal
    Description: open
    Keywords: Ionosphere ; radio waves ; high frequency ; field strength ; prediction ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 6207301 bytes
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  • 2
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    Status of available N(h) model profiles (2006)
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    Publication Date: 2019-11-04
    Description: This paper attempts to highlight progress in the ionospheric electron-density height profile modelling made during the last few years. It consists of a brief review of some major aspects associated with available theoretical, parameterised and empirical N(h) models. Emphasis is placed on pointing out the key issues in the areas that are relevant for the COST 238 PRIME project.
    Description: JCR Journal
    Description: open
    Keywords: Ionosphere ; electron density models ; height profiles ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    The impact of space weather on communication (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: As a preliminary to the studies conducted by the individual Working Groups, a review has been undertaken of topics which are relevant to the space-weather phenomena that can occur. The ways in general that these can influence the state of the ionosphere are discussed. The various changes in propagation parameters that arise on Earth-space and terrestrial radio paths via the ionosphere are listed. International procedures for frequency allocation and assignment are explained and the extent to which these are influenced by propagation factors is addressed. The role of mitigation techniques to improve radio-system performance is also identified.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
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    Proposed terminology for the classification and parameters for the quantification of variability in ionosphere morphology (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Much uncertainty currently exists in the use by different workers of the term variability in describing the results of statistical analyses applied to ionospheric measurement data sets and in their relationships with various existing or new ionospheric models. Often it is not clear whether data for different time periods or different geographical areas, and if so which, are being used to formulate results. Terms are presented in the Annex which it is suggested should be used, at least once in every publication addressing this topic, to describe unambiguously what is talked about. The background to the proposed terminology is discussed. Options for variability parameters are also addressed.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosphere ; ionospheroc terminology ; space and time variation ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
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    Extreme values in ionospheric radio propagation (2006)
    INGV
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    Publication Date: 2019-11-04
    Description: Proposals are made for Earth-space and space-space paths to apply the term propagation degradation probability, analogous to basic circuit reliability adopted within the Radiocommunication Sector of the International Telecommunication Union (ITU-R) to quantify the performance of HF terrestrial ionospheric radio circuits. The principal elements characterising propagation impairments are described and formulae and a table given by the ITU-R are reproduced relating many of these effects to the path total electron content. Expressions are provided enabling estimates of the probabilities of occurrence of user-specified extreme values to be estimated in terms of their median quantities and day-to-day variabilities. The need is stressed for additional data collection and analyses both to refine the median values and to derive the required reference variability factors.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: ionosphere ; ionospheric propagation ; 01. Atmosphere::01.02. Ionosphere::01.02.05. Wave propagation
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
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    Further study of fOF2 and M(3000)F2 in different solar cycles (2006)
    Details
    Publication Date: 2019-11-04
    Description: Measured monthly median fOF2 and M(3000)F2 for Slough over six solar cycles from 1932 onwards are examined for a selection of hours and months. Data are shown as a function of twelve-monthly smoothed sunspot number. Comparisons are made for the different solar cycles and for the rising and falling halves of each cycle. Measurements for individual cycles are compared with best-fit parabolic regression lines over all cycles to investigate possible systematic long-term effects.
    Description: JCR Journal
    Description: open
    Keywords: Ionosphere ; solar-cycle dependence ; long-term mapping ; 01. Atmosphere::01.02. Ionosphere::01.02.99. General or miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
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    Further tests of the IRI and DGR model ionospheres (2006)
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    Publication Date: 2019-11-04
    Description: The present study discusses and compares the IRI and DGR ionospheric models using N(h) profiles obtained during a high solar activity period at South Uist ionosonde station. After inversion, N(h) profiles obtained from ionograms at South Uist have been compared with those derived from the IRI-90 and DGR ionospheric models. A small data set has been selected such that both geomagnetically quiet and disturbed conditions are represented. The importance of further comparisons with additional sets of N(h) profiles under different solar-geophysical conditions and at more stations has been recognized.
    Description: JCR Journal
    Description: open
    Keywords: Ionosphere ; electron density models ; height profiles ; testing ; model comparison ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
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    The ionospheric storm studies: further development of the mapping technique (2006)
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    Publication Date: 2019-11-04
    Description: The technique of using instantaneous maps for ionospheric storm studies is further developed. Integral parameters are introduced characterizing the main features of each map. These parameters are the net volumes of Δf0F2, ΔM(3000)F2and their gradients. The magnetic storm 1-2 March, 1982 was considered and it was found that before the storm commencement and in recovery phase the Net Gradient (NG) is directed steadily to the East, while in the main phase it turns southward. NG shows where the changes of the F-layer come from. The net volume of Δf0F2 (NF) correlates well with Dst and AE indices.
    Description: JCR Journal
    Description: open
    Keywords: Ionospheric storms ; instantaneous maps ; ionospheric plasma parameters ; 01. Atmosphere::01.02. Ionosphere::01.02.06. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Wetland resource evaluation and the NRA's role in its conservation. 1. Resource assessment (2021)
    National Rivers Authority | Bristol, UK
    In:  dis@fba.org.uk | http://aquaticcommons.org/id/eprint/11036 | 1256 | 2013-03-26 13:41:04 | 11036 | Environment Agency, UK (Freshwater Biological Association)
    Details
    Publication Date: 2021-06-26
    Description: This is the Wetland resource evaluation and the NRA's role in its conservation: Resource assessment report produced by the National Rivers Authority in 1995. This R&D document provides a strategy for the assessment of the wetland resource of England and Wales. As a first step the report defines wetlands in their UK context. The following working definition is suggested: Wetland is land that has (or had until modified) a water level predominantly at, near, or up to 1.5 m above the ground surface for sufficient time during the year to allow hydrological processes to be a major influence on the soils and biota. These processes may be expressed in certain features, such as characteristic soils and vegetation. The report also summarises a hydrotopographical classification of wetlands. The report then develops a strategy for the establishment of a wetland resource Inventory based on a geographical information system (GIS) as a means of storing and manipulating site data from across England and Wales.
    Description: Environment Agency Archives North West
    Keywords: Fisheries ; Limnology ; Management ; UK ; England ; Wales ; Inland waters ; Wetland ; GIS ; Resource ; Survey ; Classification ; Inventory ; Definition ; Hydrotopography
    Repository Name: AquaDocs
    Type: monograph
    Format: application/pdf
    Format: application/pdf
    Format: 76
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  • 10
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    Measurement errors in body size of sea scallops (Placopecten magellanicus) and their effect on stock assessment models (2021)
    In:  http://aquaticcommons.org/id/eprint/8761 | 403 | 2012-06-11 18:32:12 | 8761 | United States National Marine Fisheries Service
    Details
    Publication Date: 2021-06-26
    Description: Body-size measurement errors are usually ignored in stockassessments, but may be important when body-size data (e.g., from visual sur veys) are imprecise. We usedexperiments and models to quantify measurement errors and their effects on assessment models for sea scallops(Placopecten magellanicus). Errors in size data obscured modes from strong year classes and increased frequencyand size of the largest and smallest sizes, potentially biasing growth, mortality, and biomass estimates. Modelingtechniques for errors in age data proved useful for errors in size data. In terms of a goodness of model fit to the assessment data, it was more important to accommodate variance than bias. Models that accommodated size errors fitted size data substantially better. We recommend experimental quantification of errors along with a modeling approach that accommodates measurement errors because a direct algebraic approach was not robust and because error parameters were diff icult to estimate in our assessment model. The importance of measurement errors depends onmany factors and should be evaluated on a case by case basis.
    Keywords: Biology ; Ecology ; Fisheries
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 233-247
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