Preface     

Ian Campbell  Malcolm McCulloch 《Lithos》1993,30(3-4):191

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The “susceptibility factor” in the atmospheric response to periodic forcing     

William H. Campbell  Reid A. Bryson 《Journal of Earth System Science》1993,102(1):157-173

Evidence is presented of a periodic component in the inter-annual variability of precipitation and pressure data for India during June, the month of the onset of the Indian southwest monsoon. Two frequencies that explain a statistically significant percent of the variance in these data sets are the same as the two that explain most of the variance of the average monthly lunar tidal potential for June. Not only are the frequencies the same but they are also in phase which strongly suggests that lunar tides in the atmosphere do, in fact, produce an element of climatic variability. The amplitude of the atmospheric response to this periodic forcing was not constant in time but was found to be related to the long term change in northern hemispheric surface temperature. This susceptibility of the atmosphere to an external forcing results in a nonlinear relationship between forcing and response. As a result, nonlinear regression had to be used in order to adequately define the magnitude of the response at a given frequency. The ramifications of this nonlinear response are discussed. The nonlinear interaction of the northern hemisphere temperature and the 18.6 year lunar nodal cycle results in a modulation of the frequency which appears in a linear spectral analysis near 22 years. Thus, the 22-year cycle often found in meteorological data sets may instead be the result of the modulated nodal cycle.  相似文献   

Origin of the 3500-3300 Ma calc-alkaline rocks in the Pilbara Archaean: isotopic and geochemical constraints from the Shaw Batholith   总被引：1，自引：0，他引：1  

M.J. Bickle  L.F. Bettenay  H.J. Chapman  D.I. Groves  N.J. McNaughton  I.H. Campbell  J.R. de Laeter 《Precambrian Research》1993,60(1-4)

Calc-alkaline plutonic rocks, intruded at 3450Ma, comprise a major component of the Shaw Batholith in the Archaean east Pilbara Block, Western Australia. New whole-rock Pb isotopic geochronology confirms the extent of these rocks, but a minor plutonic phase is dated at 3338±52 Ma and represents a second plutonic event of the same age as much of the nearby Mt Edgar Batholith. The Sm----Nd isotopic systematics of the 3450Ma rocks imply their derivation from a heterogeneous source, which probably included a slightly older crustal component as well as a depleted mantle component. The 3338±52 Ma pluton includes components derived from crustal sources older than 3600 Ma. The geochemistry and Sm---Nd isotopic systematics of these rocks are consistent with crustal growth in the early Archaean from upper mantle sources as depleted as the modern upper mantle. The Shaw Batholith calc-alkaline suites exhibit very similar chemical trends on variation diagrams to modern calc-alkaline plutonic rocks which can be modelled by a combination of mixing and fractionation. A suite collected from outcrops displaying prominent igneous layering shows distinct geochemical trends which can be modelled by differentiation into a component enriched in ferromagnesian minerals, principally hornblende, and possibly sphene, magnetite and epidote, and into a leucocratic component containing quartz, plagioclase and K-feld-par. These Archaean calc-alkaline plutonic rocks, in common with rocks from many other Archaean calc-alkaline provinces, exhibit very fractionated REE patterns with depleted HREE contents, a feature considered to result from equilibrium with garnet at depth in lower crustal regions. The geochemistry of the Pilbara Archaean calc-alkaline rocks is identical to the subset of modern continental-margin calc-alkaline plutonic rocks with fractionated REE patterns, such as those from the central and eastern Peninsular Ranges Batholith, western USA. The tectonic setting in which the Archaean calc-alkaline rocks formed is still not known. This reflects both uncertainty associated with the petrogenesis and environments of modern calc-alkaline rocks, as well as the limited knowledge of the precise timing and relationships of plutonic, depositional and tectonic events in the Pilbara Archaean.  相似文献   

Manganese dioxide causes spurious gold values in flame atomic-absorption readings from HBr-Br₂ digestions     

W.L. Campbell 《Journal of Geochemical Exploration》1981,15(1-3)

False readings, apparently caused by the presence of high concentrations of manganese dioxide, have been observed in our current flame atomic-absorption procedure for the determination of gold. After a hydrobromic acid (HBr)-bromine (Br₂) leach, simply heating the sample to boiling to remove excess Br₂ prior to extraction with methyl-isobutyl-ketone (MIBK) eliminates these false readings.  相似文献   

Baseline levels of heavy metals in the waters and sediments of Baffin Bay     

J.A. Campbell  D.H. Loring 《Marine pollution bulletin》1980,11(9):257-261

Baseline levels of a number of trace metals have been determined in samples of water and sediment from Baffin Bay. Concentrations of Cr, Mn, Fe, Ni, Cu and Cd in the waters of Baffin Bay are generally lower than those observed in eastern Canadian coastal waters, levels being close to reported open ocean concentrations. Nearshore sediment samples, analysed for Cr, V, Mn, Ni, Co, Cu, Zn, Hg and Pb, display comparable concentrations to unpolluted muds in eastern Canadian coastal regions. Concentrations of these elements in the deep sediments of central Baffin Bay closely resemble levels in Atlantic Ocean deep-sea clays.  相似文献   

Windspeed dependence of heat and mass transfer through coats and clothing     

G. S. Campbell  A. J. McArthur  J. L. Monteith 《Boundary-Layer Meteorology》1980,18(4):485-493

Penetration of a layer of fibre by wind reduces its effectiveness as a barrier to heat flow. In the literature, the dependence of coat or clothing insulation I(u) on windspeed u is usually described by a relation of the form I(u) = I(0) – au ^1/2, where a is a constant. Re-analysis reveals that it is more appropriate to treat coat conductance (proportional to 1/I) as a linear function of windspeed. Vapour conductance can also be treated as a linear function of windspeed.On leave from Washington State University, Department of Agronomy and Soils.  相似文献   

Arctic sea-ice variations from time-lapse passive microwave imagery     

W. J. Campbell  R. O. Ramseier  H. J. Zwally  P. Gloersen 《Boundary-Layer Meteorology》1980,18(1):99-106

This paper presents: (1) a short historical review of the passive microwave research on sea ice which established the observational and theoretical base permitting the interpretation of the first passive microwave images of Earth obtained by the Nimbus-5 ESMR; (2) the construction of a time-lapse motion picture film of a 16-month set of serial ESMR images to aid in the formidable data analysis task; and (3) a few of the most significant findings resulting from an early analysis of these data, using selected ESMR images to illustrate these findings.  相似文献   

A re-evaluation of the olivine-spinel geothermometer   总被引：1，自引：0，他引：1  

Peter L. Roeder  Ian H. Campbell  Heather E. Jamieson 《Contributions to Mineralogy and Petrology》1979,68(3):325-334

The Irvine olivine-spinel geothermometer, as formulated by Jackson (1969), appears to yield magmatic temperatures when applied to plutonic rocks such as the Stillwater Complex but Evans and Wright (1972) have demonstrated that it gives temperatures in excess of 2,000 ° C when applied to volcanic assemblages. A re-evaluation of the geothermometer has shown that more realistic temperatures can be obtained for volcanic rocks by using a different free energy value of FeCr₂O₄ in the formulation. The revised geothermometer gives temperatures in the range 1,100–1,300 ° C for samples from Kilauea and 500–800 ° C for basic plutonic rocks from layered intrusions, indicating that Mg and Fe²⁺ have re-equilibrated at subsolidus temperatures in these intrusions as suggested by Irvine (1965). This theory was tested by heating uncrushed natural samples from layered intrusions to magmatic temperatures for periods ranging from two days to four weeks. The result was a marked increase in the Mg/Fe²⁺ ratio in the spinels and a decrease in the Mg/Fe²⁺ ratio in the olivines, confirming that considerable subsolidus re-equilibration had taken place in the unheated samples.  相似文献   

Firth of Forth oil pollution incident, February 1978     

L. H. Campbell  K. T. Standring  C. J. Cadbury 《Marine pollution bulletin》1978,9(12):335-339

Where seaducks and other waterfowl are highly concentrated, even small quantities of oil can be a major hazard. A pollution incident on the Firth of Forth in February 1978 was notable in that it affected 241 Great Crested Grebes Podiceps cristatus (a high proportion of those present at the time) as well as 700 diving ducks. Evidence is provided indicating that the slick passed close to the main wildfowl feeding area at night, oiling nocturnal-feeding Scaup Aythya marila and Pochard A. ferina and a raft of roosting grebes, while Eider Somateria mollissima and Goldeneye Bucephala clangula, which had moved elsewhere to roost, largely escaped. The behaviour of freshly oiled birds is described. Heavily oiled Pochard flew 7 km inland to a loch before they were incapacitated. This is the sixth oil pollution incident to affect a large number of birds on the Forth since January 1970.  相似文献   

Some problems with the cumulus theory   总被引：17，自引：0，他引：17  

I. H. Campbell 《Lithos》1978,11(4):311-323

There are a number of features in layered intrusions which do not appear to be consistent with the cumulus theory. The most important of these are: (1) Rhythmic layering in plagioclase-pyroxene cumulates from some intrusions (e.g. Jimberlana and Stillwater) may be inverted with the light plagioclase-rich cumulates at the base of the layer and heavy pyroxene-rich cumulates at the top. (2) Hydraulic sorting in rhythmically layered cumulates is often poor, suggesting that chemical and not mechanical processes control the distribution of minerals in this type of layered sequence. (3) The textures of cumulates from the steeply dipping marginal zone of Jimberlana, which cannot have formed by gravity settling, are indistinguishable from those found in the flatly dipping central layers of the intrusion. Similarly, it is difficult to explain the cumulate textures in the ‘overturned’ marginal layered series of Jimberlana. (4) Igneous layering, including cross-bedding, graded bedding and trough banding, has been described in layered sequences with near-vertical primary dips. (5) Calculations and experiments with a centrifuge furnace suggest that plagioclase cannot sink in Fe-rich tholeiitic liquids. (6) The settling of crystals as individual grains assumes that nucleation is homogeneous. This is unlikely.

It is probable that heterogeneous and self-nucleation are the dominant nucleation mechanisms during the formation of cumulates. This gives rise to two possibilities. Firstly, that most grains nucleate against pre-existing settling crystals to form composite grains which gravitate to the floor of the chamber. Secondly, that the cumulus grains nucleate in situ at the temporary floor of the magma chamber.  相似文献