Reconstruction of New Zealand Temperatures Back to AD 1720 Using Libocedrus bidwillii Tree-Rings     

Limin Xiong  Jonathan G. Palmer 《Climatic change》2000,45(2):339-359

The longest chronology from New Zealand so faris from Libocedrus bidwillii Hook. f. (i.e.,from AD 1992 back to AD 1140, a span of 853 years). A subset of 11 chronologies was selected from anetwork of 23 sites to reconstruct past temperaturesbased on the similarity of significant responsefunctions. A comparison of climate data overdifferent seasons with these 11 chronologies wascarried out using a bootstrap transfer function. Average late-summer (February–March) temperature wasselected for reconstruction based on independentverification results. The reconstructed temperaturewas then presented for the period back to AD 1720. The chronologies reconstructed years experiencing hotsummers better than cold summers. The power spectrumof the reconstructed temperatures showed periodicitiessimilar to those of the observed temperatures. Reconstructed temperatures were significantlycorrelated with other proxy climate reconstructionsderived from tree rings in New Zealand. However,unlike the other tree ring-based reconstructions, theLibocedrus bidwillii series reconstructed boththe 1950s and 1970s warming periods. The resultsalso compared very favourably with other palaeoclimateevidence.  相似文献   

An analytical description of three-dimensional heliocentric solar sail orbits     

Brian Stewart  Phil Palmer  Mark Roberts 《Celestial Mechanics and Dynamical Astronomy》2017,128(1):61-74

  相似文献   

Speleothem stable isotope records interpreted within a multi-proxy framework and implications for New Zealand palaeoclimate reconstruction   总被引：1，自引：0，他引：1  

Andrew Lorrey  Paul Williams  Jim Salinger  Tim Martin  Jonathan Palmer  Anthony Fowler  Jian-xin Zhao  Helen Neil 《Quaternary International》2008,187(1):52

A primary step in the interpretation of speleothem stable isotope records (¹⁸O/¹⁶O and ¹³C/¹²C) is to conduct a comparison with other local palaeoclimate proxies. Here, two new master speleothem δ¹⁸O and δ¹³C records (one from eastern North Island, and the other from western/southern South Island, New Zealand) are evaluated against independent precipitation and temperature proxy information to assess their palaeoclimate reconstruction potential. This comparison also resulted in a serendipitous opportunity to reconstruct past circulation using climate regime classification [Lorrey, A.M., Fowler, A.M., Salinger, J., 2007a. Regional climate regime classification as a qualitative tool for interpreting multi-proxy palaeoclimate data spatial patterns: a New Zealand case study. Palaeo-3, in press], specifically because these two regional climate districts are hyper-sensitive to westerly circulation changes, and in many cases, exhibit contrasting climate character in response to circulation anomalies.For both the western South Island and the eastern North Island master speleothem δ¹³C records, variations tracked changes in relative regional precipitation. The δ¹⁸O master speleothem record for both regions varied with temperature change. Both records contain strong regional climate signals that suggest they have good value for palaeoclimate reconstruction. The ensuing attempt at a multi-proxy reconstruction of regional climate regimes from the compiled proxies indicates past circulation in the New Zealand sector has varied considerably during the past four millennia. Centennial-scale circulation changes for the past 4000 years are evident, and are analogous to modern Blocking, Zonal and Trough regime types [Kidson J. W., 2000. An analysis of New Zealand synoptic types and their use in defining weather regimes. International Journal of Climatology 20, 299–316] that characterise changes in present-day (prevailing) westerly circulation. This palaeoclimate reconstruction indicates modern regional climate regime classification can be extended at least as far back as the temporal coverage of the records presented here, and it can likely be improved on with better dating control and the addition of new records with higher resolution. It is also anticipated that future work will expand to include more proxy data from across New Zealand to improve the clarity of past climate regime occurrence for the Late Holocene.  相似文献   

Phase transitions in leucite: Order parameter behaviour and the Landau potential deduced from Raman spectroscopy and birefringence studies     

David C. Palmer  Ulrich Bismayer  Ekhard K. H. Salje 《Physics and Chemistry of Minerals》1990,17(3):259-265

Hard mode Raman Spectroscopy and optical birefringence studies have been used to evaluate the temperature behaviour of order parameters for the cubictetragonal phase transition in leucite. There is a strong temperature-dependence of Raman line frequencies near 498 cm^–1 and 529 cm^–1, and the optical birefringence decreases towards zero on heating. Above the transition temperature leucite still shows slight birefringence, which correlates with the persistence of the 200 X-ray reflexion at these temperatures, and is not compatible with the ideal cubic symmetry. Quantitative observations of the temperature evolution of Raman line-frequencies and the birefringence are consistent with an order parameter showing T _1g symmetry, and a nearly-tricritical phase transition behaviour. The results of earlier X-ray and DSC studies imply the operation of an additional order parameter, with E _g symmetry; this is observed, but its influence on the transition behaviour is significant only at temperatures close to T _c. The two order parameters are related via linear-quadratic or biquadratic coupling. We develop the form of the Landau Potential for leucite — including both order parameters and their couplings — to discuss the present observations and previous structural data.  相似文献   

STEREOSCOPY AND PHOTOGRAMMETRY     

D. A. Palmer 《The Photogrammetric Record》1964,4(23):391-394

  相似文献   

Dilute-acid trace-metal fraction in northeastern Gulf of Mexico sediments     

Peter H. Feldhausen  Harold D. Palmer  David Johnson 《Geo-Marine Letters》1982,2(1-2):95-100

Variations in dilute-acid (partial digest) metal concentrations in bottom sediments from 49 stations on the Mississippi, Alabama and Florida continental margin are investigated with the aid of ordination and other multivariate statistical techniques. Total iron, carbonate content, clay fraction and water depth correlate well with the overall leachable sediment metal values for pooled station replicates over four sampling periods. Individual metal concentrations also are correlated with these and other environmental parameters using stepwise multiple linear regression techniques. A weak positive association between Ba, Cu, Cr, Ni, Pb, and V burdens in the demersal fishSyacium papillosum and the dilute-acid leachable sediment metal TOC and carbonate concentrations is demonstrated.  相似文献   

Structure of the Cobar Basin,New South Wales,based on seismic reflection profiling     

R. A. Glen  B. J. Drummond  B. R. Goleby  D. Palmer  K. D. Wake‐Dyster 《Australian Journal of Earth Sciences》2013,60(4):341-352

The Cobar Basin in central western New South Wales is a mineral‐rich Early Devonian basin typical of those that characterize the Siluro‐Devonian history of the Lachlan Orogen of southeastern Australia. One hundred and seventy kilometres of seismic profiling in three lines across the basin have shown it to be asymmetrical in shape with an east‐dipping western margin that is steeper than the moderately west‐dipping eastern margin. Maximum basin thickness is around 6 km, but there are significant thickness changes, especially from south to north, which reflect the effect of synsedimentary faulting. Seismic profiling suggests that the basin deformed by thin‐skinned tectonics; postulated strike‐slip effects were not visible on the sections. The seismic profiling has, for the first time, imaged the western synrift basin margin which is generally not exposed. Strain variations during deformation along this edge were taken up by the formation of a major jog ('dog‐leg') which has propagated into the basin as a tear fault. Intrabasinal tears, as well as thrusts, which link into one or more detachments, provide potential pathways for mineralizing fluids during basin inversion.  相似文献   

Blast Damage and Blast Dilution Control: The Application of Bulk Emulsion Systems at the WMC St Ives Junction Mine     

T. M. Law  J. May  A. T. Spathis  A.T. Du Plessis  A. M. Palmer 《Fragblast: International Journal for Blasting and Fragmentation》2001,5(1):1-20

The application of modern bulk emulsion explosive systems at an underground gold mine resulted in a 57% improvement in gold dilution. While this improvement is impressive and could be expected to be achieved at other sites, the work required to assess and demonstrate the benefits is painstaking. Forty-eight rings involving a total of approximately 50 000 tonnes of ore were monitored using various modern surveying instruments over a 6-month period. The geometric data included blasthole locations and deviation, and the cavity monitoring of stopes. Implementation of a bulk emulsion system not only provided logistical benefits but it also has the desirable explosive properties associated with reducing the effects of blast damage and blast dilution.  相似文献   

Ion migration in nepheline: a dielectric spectroscopy and computer modelling study     

A. Jones  D. Palmer  M. S. Islam  M. Mortimer 《Physics and Chemistry of Minerals》2001,28(1):28-34

 Using a combination of dielectric spectroscopy and atomistic computer simulation techniques, the dynamical behaviour of the loosely bound (Na⁺ and K⁺) channel ions in nepheline has been investigated. The low-frequency dielectric properties of a natural Bancroft nepheline have been studied from room temperature to 1100 K. At each temperature, the dielectric constant, conductivity and dielectric loss were determined over a range of frequencies from 100 Hz to 10 MHz. At high temperatures a distinct Debye-type relaxation in the dielectric loss spectrum was observed; the activation energy for this process was determined to be 1.38 ± 0.02 eV. Atomistic simulation techniques were used to elucidate the mechanism and energetics of cation migration. A mechanism involving the hopping of Na⁺ ions between oval sites and partially occupied hexagonal (K⁺) sites, via a bottleneck consisting of a distorted sixfold ring of (Al,Si)O₄ tetrahedra, was found to give a calculated energy barrier in very good agreement with the experimentally determined activation energy. These results confirm the nature of the process responsible for the observed dielectric behaviour. Overall, this study demonstrates the intrinsic, microscopic control of cation diffusion processes in rock-forming minerals. Identifying specific energy barriers and preferred diffusion pathways is fundamental to the prediction of diffusion energetics. Received: 8 May 2000 / Accepted: 21 July 2000  相似文献   

The association of polar mesosphere summer echo layers with tial modes     

P. J. S. Williams  G. O. L. Jones  J. R. Palmer  H. Rishbeth 《Annales Geophysicae》1995,13(4):454-457

The occurrence of PMSEs with time of day shows a semi-diurnal variation with minima at 8 and 20 h LT. PMSE layers observed for more than 30 min show an average rate of descent of 2 km h⁻¹. These characteristics suggest the influence of tidal winds. When the observed steady wind and diurnal and semi-diurnal tides at EISCAT are added, the overall magnitude shows a time-variation which matches the occurrence of PMSEs, and the observed rate of descent, approximately 2 km h⁻¹. Atmospheric gravity waves also contribute to the velocity of the neutral wind. When the wave reinforces the background wind, the PMSEs are stronger and descend more rapidly, but when the wave-related velocity opposes the background wind the PMSE is weaker and it descends more slowly.  相似文献