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ABSTRACTThe sinking of the MV Rena on Astrolabe Reef (Otaiti) in the Bay of Plenty, New Zealand, resulted in the release of oil and ship debris, including dangerous goods carried as cargo. Two key questions of concern to the public and environmental managers were posed immediately: what was the impact of the Rena oil spill and how long would it take for the marine environment to recover? The research that began immediately after the ship grounded provided answers, as documented in this special issue. 相似文献
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DR. M. ERDÉLYI 《水文科学杂志》2013,58(1):44-52
SUMMARY Many hydrological systems exhibit long periods of quiescent behaviour, broken only occasionally by short periods of comparatively intense activity. Clear examples arise in stream run-off measurements and in ground water table observations. The number of measurements recorded can then be considerably reduced by reducing the frequency of recording over the quiescent periods. The paper describes an algorithm whereby this reduction is attained in an optimum manner. When recordings can be accepted directly by a computer, the algorithm simply provides a translation programme Whereby the quality of data may be very considerably reduced. Other applications are, however, discussed. The problems of Optimum representations is first presented, and choices of norm indicated. Using a particular norm, it is shown that the optimum representation is characterised, under certain limiting conditions, by the property that the second moments of the second derivatives are constant over all optimum intervals. This characterisation is used to construct an iterative difference scheme, whereby a certain truncation error is accepted. Sufficient conditions for stability of the scheme are determined and these incorporated into a computer programme. The programme has been tested on a variety of data with satisfactory results. In conclusion, a further development of the method is indicated. 相似文献
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In an earlier paper the latitudinal and longitudinal structure of ionospheric current flow during a sequence of magnetospheric substorms was presented (McDiarmid and Harris, 1976). In the present paper the relationships between the electrojets, the radio aurora observed at 48 MHz and the all-sky camera-recorded visual aurora are presented for the same substorm sequence. The previously described morphology of radio aurora during substorms is confirmed and the observed relationships can be explained. 相似文献
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D.R. McDiarmid 《Planetary and Space Science》1979,27(8):1123-1125
It is shown that the combined spatial and temporal oscillation of the auroral electrojet proposed by Rostoker and Lam (1978) gives rise to a second harmonic in the ground recorded pulsation record. An alternate spatial and temporal variation which does not inherently produce higher harmonics is proposed. It is suggested that both proposals require further theoretical and/or experimental investigation. 相似文献
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The structure of a sequence of four spatially and temporally connected magnetospheric substorms has been determined through the use of a set of mid-latitude magnetometer station data, an auroral zone magnetometer line data set, and the ATS-5 magnetometer record. In two of the substorms, two parallel westward electrojets were observed to develop during the initial part of the expansion phase. In another, the expansion phase consisted of the development of a westward electrojet westward and equatorward of the pre-existing current system. 相似文献
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In the weeks following the 2011 Rena oil spill, a series of surveys was initiated on eight rocky intertidal reefs to describe the distribution of oil and to assess the impacts of oil on ecological communities. Consistent but relatively low cover of oil occurred at two sites (Mt Maunganui and Moturiki). The area covered by oil had decreased by c. 90% after 5 months due to natural weathering processes. There were immediate effects of oil fouling on the mussel Limnoperna pulex and its associated fauna, with reductions in the number of mussels and infaunal taxonomic richness. However, no ecological effects on any of the communities were detectable after 1 month. Overall, the ecological effects of the Rena oil spill on rocky shore intertidal communities were small and not long-lasting, but we stress that this does not consider potential sublethal effects and their consequences on organisms. 相似文献