‘Splendid rains have fallen’: links between El Niño and rainfall variability in the Kalahari, 1840–1900     

David J. Nash  Georgina H. Endfield 《Climatic change》2008,86(3-4):257-290

This study uses a range of published and unpublished historical documentary sources to explore the nature of rainfall variability in the Kalahari Desert and adjacent hardveld regions of central southern Africa during the seventeen Pacific El Niño–Southern Oscillation (ENSO) episodes that occurred between 1840 and 1900. Documentary data are used in two ways. First, maps of relative annual rainfall levels are presented for each of the 12 single-year and five protracted ENSO episodes during the period, in order to identify the associated inter-annual rainfall variations. These suggest that the relationship between ENSO episodes and rainfall variability identified for the twentieth century, whereby warm events are frequently preceded by wetter conditions during the austral summer prior to the event year and succeeded by drought in the following summer, has broadly held for much of the last 160 years. This is despite the long-term fluctuations in precipitation and temperature which are known to have occurred over this period. Droughts are identified following at least thirteen of the 17 single-year and protracted ENSO episodes. Pre-ENSO wetter periods are less common, with only nine of the ENSO episodes preceded by above-normal rainfall. Second, the documentary data are analyzed in detail in order to reveal any evidence for high resolution intra-annual variations in the seasonal distribution of rainfall during ENSO events. Seasonal sequences of rainfall/drought appear to have closely followed contemporary patterns, with heavy rainfall commonly occurring late in the pre-ENSO year or early in the ENSO year(s), and drought at the start of the post-ENSO year. This relationship can be seen to hold most strongly for single-year ENSO warm events and for the first year of protracted events, but rainfall conditions were more variable during the later years of protracted events.  相似文献   

An application of the annual egg production method to estimate the spawning biomass of cod (Gadus morhua L.), plaice (Pleuronectes platessa L.) and sole (Solea solea L.) in the Irish Sea   总被引：1，自引：0，他引：1  

Armstrong  M. J.; Connolly  P.; Nash  R. D. M.; Pawson  M. G.; Alesworth  E.; Coulahan  P. J.; Dickey-Collas  M.; Milligan  S. P.; O'Neill  M. F.; Witthames  P. R.; Woolner  L. 《ICES Journal of Marine Science》2001,58(1):183-203

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The Diel Behaviour of Small Demersal Fish on Soft Sediments on the West Coast of Scotland using a Variety of Techniques: with Special Reference to Lesueurigobius friesii (Pisces; Gobiidae)     

R. D. M. Nash 《Marine Ecology》1982,3(2):161-178

Abstract. The diel behaviour of communities of small demersal fishes was studied in situ on the west coast of Scotland using trawling, diving, underwater television and underwater time-lapse photography techniques. Lumpenus lampretaeformis and Pomatoschistus norvegicus were shown to have crepuscular behaviour patterns. Lesueurigobius friesii was a day active fish, spending the night close to or within its burrow and feeding through the day. Disruptions to this behaviour pattern occurred at high abundances of gadoids and during the spawning season. The fish community as a whole showed a crepuscular periodicity. The various observational methods are discussed. There did not appear to be any close association between Lesueurigobius friesii and the decapod Nephrops norvegicus.  相似文献   

“Future studies” and the geo-bio-sciences     

Dr. Peter H. J. Nash Sr. 《GeoJournal》1977,1(6):13-16

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Drought, desiccation and discourse: missionary correspondence and nineteenth-century climate change in central southern Africa   总被引：1，自引：0，他引：1  

Endfield GH  Nash DJ 《The Geographical journal》2002,168(1):33-47

This paper examines the role that representatives of the London Missionary Society in central southern Africa during the nineteenth century may have played in the development of geographical debates concerning the long-term desiccation of the African continent. Observations on climate included within missionary documents are used to reconstruct a chronology of intra-decadal climatic variability for the period 1815–1900. This reveals six drought periods and seven wet phases that affected large areas of the region, but identifies no evidence for progressive desiccation. The chronology is then used as a framework within which to view missionary perspectives on drought and desiccation. Major influences upon the development of desiccationist theory appear to include the prevalence of contemporary moral economic explanations of climatic variability, as well as the uptake and acceptance of indigenous understanding of climate change. Significantly, many of the key observations by eminent missionaries used as supporting evidence for progressive desiccation are identified as having been made during periods of severe drought. This is used to suggest that the most widely propagated evidence for desiccation may, therefore, simply be the end-product of periods of short-term drought rather than long-term climatic deterioration.  相似文献   

Application of high resolution seismic reflection techniques for fracture mapping in crystalline rocks     

W.M. Moon  J.S. Kim  Ganpat Lodha  Mulu Serzu  Nash Soonawala 《Engineering Geology》1993,34(3-4):261-280

Surface reflection seismic techniques have the capability of mapping subsurface geological features without disturbing the rock mass. They also have an added capability of penetrating to a much deeper depth than any other geophysical technique, including the ground probing radar. However, the successful application of reflection seismic techniques in crystalline rocks has in general been more difficult than in sedimentary basins, because of the irregular geometry and low acoustic impedance contrasts across geological boundaries. In this paper, we describe the imaging of fracture zones in crystalline rocks. Effective data processing, carefully modified from the conventional approaches, was applied on two high-resolution field data previously collected by different contractors. The strategy included enhancement of the signal hidden under the large-amplitude scattering noise, through pre- and post-stack processing such as shot f-k filtering, residual statics and careful muting after NMO correction. Two sets of low S/N test data from Canada and Sweden are analyzed in this research. The reflected energy in these data sets appeared to be more closely related to fracturing than to lithologic boundaries. The major fracture zones at shallow depth have been mapped with the desired resolution and can be correlated to the available well-log and seismic crosshole tomographic data. Once the surface waves were removed, shallow reflectors in the fracture zones could be identified and analyzed on the field records. Focusing analysis of the seismic image was performed in the constant-offset section to investigate the trends of major fracture zones. The complex attributes were also analyzed to determine whether they could be applied to the shallow fracture zones. Instantaneous frequency plots outline the intense fracturing zone and instantaneous phase plots identify the major and minor fractures, and other coherent events with different dip attitudes which interfere with each other.  相似文献   

Application of a novel phytotoxicity assay for the detection of herbicides in Hervey Bay and the Great Sandy Straits   总被引：1，自引：0，他引：1  

Bengtson Nash SM  McMahon K  Eaglesham G  Müller JF 《Marine pollution bulletin》2005,51(1-4):351-360

A novel phytotoxicity assay was incorporated into an environmental assessment of Hervey Bay and the Great Sandy Straits, to investigate the role of run-off associated herbicides in the deteriorated health of intertidal seagrass meadows. Dose response curves of common herbicides were performed and their toxicity equivalents elucidated to assist in analysis. The results of the assay were reproducible and corresponded strongly with results of chemical analyses. The incorporation of the assay into the assessment of surface waters added an important aspect to the study by allowing investigation of the toxicity of cumulative herbicide concentrations and yielding biologically relevant data. The highest herbicide concentration detected during the study was equivalent to 0.23 microg l(-1) diuron; a concentration known to inhibit photosynthetic efficiency of the assay biomaterial by approximately 3%.  相似文献   

Ilmenite-orthopyroxene intergrowths from the moon and the Skaergaard intrusion     

J.D. Haselton  W.P. Nash 《Earth and Planetary Science Letters》1975,26(3):287-291

Myrmekitic or eutectic-like intergrowths of ilmenite and orthopyroxene, which texturally resemble intergrowths from nodules in kimberlites have been observed in lunar breccia 60016, 92 and in Lower Zone a of the Skaergaard intrusion. The lunar sample is similar in mineral chemistry to kimberlite occurrences, while the Skaergaard sample is not as Mg-rich. In all cases, however, there is a systematic distribution of Mg between orthopyroxene and ilmenite. The similar textures were formed by different processes: the lunar intergrowth is probably a eutectic-type texture resulting from crystallization of a melt, while the Skaergaard intergrowth formed by a process of sub-solidus oxidation.  相似文献   

Soils with variable charge | B.K.G. Theng, 1980. New Zealand Society of Soil Science,Lower Hutt,xv+448 pp., $NZ 25.00, postage etc. of $NZ 3     

V.E. Nash 《Earth》1982,18(1):101-102

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Book reviews     

E. M. Yates  W. Manshard  Yrjö Vasari  Jacob O. Maos  C. A. Halstead  Dieter Steiner  Thomas Peucker  Lisbeth Seeley-Heuse  Olof Hedbom  Howard F. Gregor  K.-Seguin Maurice  Klaus-Achim Boesler  C. Koeman  G. H. T. Hart  H. Dequin  M. Richter  Peter H. Nash 《GeoJournal》1980,4(4):381-388

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