Erratum to: Predicting June Mean Rainfall in the Middle/Lower Yangtze River Basin     

Gill M. MARTIN  Nick J. DUNSTONE  Adam A. SCAIFE  Philip E. BETT 《大气科学进展》2020,37(9):1032-1032

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Sunset on Heimdall's Stones. A View from Archaeology and Archaeoastronomy of the Ravlunda 169 Iron Age Cemetery     

ALUN SALT  MARTIN RUNDKVIST 《Geografiska Annaler: Series A, Physical Geography》2011,93(3):193-196

Salt, A. and Rundkvist, M., 2011. Letter to the editor: Sunset on Heimdall's stones. A view from archaeology and archaeoastronomy of the Ravlunda 169 Iron Age cemetery. Geografiska Annaler: Series A, Physical Geography, 93, 193–196. DOI: 10.1111/j.1468‐0459.2011.00428.x  相似文献   

A Holocene seabird record from Raffles Sø sediments, East Greenland, in response to climatic and oceanic changes     

BERND WAGNER  MARTIN MELLES 《Boreas: An International Journal of Quaternary Research》2001,30(3):228-239

A 3.5-m-long sediment sequence from a lake on Raffles Ø, off Liverpool Land, East Greenland, was investigated for chronology, lithology, palynology and biogeochemistry. Radiocarbon-dating of plant remains and the lithology of the sediment succession indicate continuous sedimentation since deglaciation of the area prior to 10000 cal. yr BP. The postglacial palynological record shows little variation and evidence of a wind-transported pollen supply, both resulting from the geographical characteristics of Raffles Ø. Significant variations in the biogeochemical data reflect changes in aquatic bioproduction. These changes depend to some extent on climatic changes; however, they are mainly due to variations in seabird breeding colonies in the catchment which influence nutrient and cadmium supply to the lake. Large seabird breeding colonies were present between 7500 and 1900, from 1000 to 500, and since c. 100 cal. yr BP. Their absence prior to 7500 cal. yr BP may be the result of unsuitable feeding conditions close to Raffles Ø caused by a too dense or too open sea-ice cover. In contrast, between 1900 and 1000 and from 500 to 100 cal. yr BP, the seabird settlement was probably restricted by an insufficiently long breeding season due to cold climate conditions in East Greenland.  相似文献   

Late Neanderthal occupation in North‐West Europe: rediscovery,investigation and dating of a last glacial sediment sequence at the site of La Cotte de Saint Brelade,Jersey     

MARTIN BATES  MATTHEW POPE  ANDREW SHAW  BECCY SCOTT  JEAN‐LUC SCHWENNINGER 《第四纪科学杂志》2013,28(7):647-652

In 2011, a programme of field research was undertaken to effect the stabilization of an unstable section in the West Ravine at the key Neanderthal occupation site of La Cotte de St Brelade on the Channel Island of Jersey. As part of this essential remedial work the threatened section was analysed to characterize its archaeological and palaeoenvironmental potential as well provide optically stimulated luminescence (OSL) dates. The work determined, through two concordant OSL dating programmes, that the section formed part of an extensive sequence of sedimentation spanning >105 to <48 ka. Furthermore, reanalysis of the archive determined that the sediment sequence examined contained the stratigraphic equivalent of deposits lying below those that have previously produced Neanderthal fossils. Through our work, we can now constrain these younger sediments to being younger than 48 ka. The combined results suggest that this sequence now represents the recovery of an extensive dataset, thought lost to science through complete excavation, which holds the potential to throw light on the disappearance of Neanderthal populations from the Atlantic‐edge outpost on the north‐west frontier of their world.  相似文献   

Depolarization ratio profiling at several wavelengths in pure Saharan dust during SAMUM 2006   总被引：1，自引：0，他引：1  

By VOLKER FREUDENTHALER  MICHAEL ESSELBORN  MATTHIAS WIEGNER  BIRGIT HEESE  MATTHIAS TESCHE  ALBERT ANSMANN  DETLEF MÜLLER  DIETRICH ALTHAUSEN  MARTIN WIRTH  REAS FIX  GERHARD EHRET  PETER KNIPPERTZ  CARLOS TOLEDANO  JOSEF GASTEIGER  MARKUS GARHAMMER  MEINHARD SEEFELDNER 《Tellus. Series B, Chemical and physical meteorology》2009,61(1):165-179

Vertical profiles of the linear particle depolarization ratio of pure dust clouds were measured during the Saharan Mineral Dust Experiment (SAMUM) at Ouarzazate, Morocco (30.9°N, –6.9°E), close to source regions in May–June 2006, with four lidar systems at four wavelengths (355, 532, 710 and 1064 nm). The intercomparison of the lidar systems is accompanied by a discussion of the different calibration methods, including a new, advanced method, and a detailed error analysis. Over the whole SAMUM periode pure dust layers show a mean linear particle depolarization ratio at 532 nm of 0.31, in the range between 0.27 and 0.35, with a mean Ångström exponent (AE, 440–870 nm) of 0.18 (range 0.04–0.34) and still high mean linear particle depolarization ratio between 0.21 and 0.25 during periods with aerosol optical thickness less than 0.1, with a mean AE of 0.76 (range 0.65–1.00), which represents a negative correlation of the linear particle depolarization ratio with the AE. A slight decrease of the linear particle depolarization ratio with wavelength was found between 532 and 1064 nm from 0.31 ± 0.03 to 0.27 ± 0.04.  相似文献   

ABLATION OF ICE‐CORED MORAINE IN A HUMID,MARITIME CLIMATE: FOX GLACIER,NEW ZEALAND     

MARTIN S. BROOK  SHERYL PAINE 《Geografiska Annaler: Series A, Physical Geography》2012,94(3):339-349

Depending on thickness, debris‐cover can enhance or reduce ablation, compared to bare‐ice conditions. In the geological record, hummocky moraines often represent the final product of the melt‐out of ice‐cored moraines, and the presence or absence of such moraine deposits can have paleoclimatic implications. To evaluate the effects of varying debris‐cover and climate on ice‐melt in a maritime mid‐latitude setting, an 11‐day ablation stake study was undertaken on ice‐cored moraine at Fox Glacier, on the western flank of the New Zealand Southern Alps. Ablation rates varied from 1.3 to 6.7 cm d^?1, with enhancement of melt‐rate under thin debris‐covers. Highest melt‐rates (effective thickness) occurred under debris‐cover of c. 2 cm, with ～3 cm being the debris thickness at which melt‐rates are equal to adjacent bare‐ice (critical thickness). Air temperature from nearby Franz Josef Glacier allowed for a simple degree‐day approach to ablation calculations, with regression relationships indicating air temperature is the key climatic control on melt. Digital elevation models produced from topographic surveys of the ice‐cored moraine over the following 19 months indicated that ablation rates progressively decreased over time, probably due to melt‐out of englacial debris increasing debris‐cover thickness. The morphology of the sandur appears to be strongly determined by episodic high‐magnitude fluvial flows (jökulhlaups), in conjunction with surface melt. Thus, ‘hummocky’ moraine appears to be a transient landform in this climatic setting.  相似文献   

Experimental insights into laser diffraction particle sizing of fine‐grained sediments for use in palaeoceanography     

LUKAS JONKERS  MAARTEN A. PRINS  GEERT‐JAN A. BRUMMER  MARTIN KONERT  BRYAN C. LOUGHEED 《Sedimentology》2009,56(7):2192-2206

Grain‐size measurements of fine‐grained sediments based on laser diffraction may contain spurious information due to the over‐estimation of the size and proportion of platy particles. Consequently, some regard the use of laser diffraction particle sizing in palaeoceanography inappropriate. Here, it is shown experimentally that such concerns are not warranted. Laser diffraction particle sizing is known to be fast, precise and allows for detailed particle sizing over a broad size range; it is therefore potentially a very powerful technique if the complications associated with it can be overcome. As most sediments are mixtures of different components transported by different mechanisms, inferences of past environmental parameters require decomposition of the grain‐size record in question. Useful decomposition can only be performed if changes in the contribution of the components are registered predictably by the measuring device. This study reports on mixing experiments which show that the Fritsch A22 laser diffraction particle sizer does indeed register small changes in the contribution of the mixing components in a predictable way. Mixing proportions estimated from the measurements do, however, differ from the initial mixing proportions, but these can be converted with only small errors. Application of the conversion equations to a North Atlantic grain‐size record that showed consistent slowdown of deep‐ocean circulation in response to millennial scale ice‐rafting events during the last glacial does not quantitatively affect the original inferences. Laser diffraction particle sizing of fine‐grained sediments therefore yields reproducible and useful data for palaeoceanographic reconstructions.  相似文献   

The Palaeozoic history of the Western Desert of Egypt   总被引：1，自引：0，他引：1  

MARTIN L. Keeley 《Basin Research》1989,2(1):35-48

Abstract A formal stratigraphical scheme is proposed for the Palaeozoic succession encountered in the subsurface of the Western Desert of Egypt, and is compared to other published schemes in North Africa. Two groups and seven formations span the interval from the Mid Cambrian to the Early Permian. The resolution between these superficially similar clastic-dominated units is enhanced by the use of the palyno-stratigraphical zonation devised by Gueinn & Rasul. It is apparent from an analysis of this rock sequence that two depositional regimes can be recognized. In the first of these, the Ghazalat Basin lay over the central Western Desert, and was bounded by high axes to the west and south-east. An inversion event of Early Tournaisian age preceded a new depositional regime, centred along the Libyan border: the Tehenu Basin. A poorly understood sequence of strike-slip movements on the Trans-African Lineament is shown to be the most likely cause of this complex basin history. One consequence of this hypothesis is, however, to throw into question the validity of correlations made with the Gulf of Suez Palaeozoic succession, across the Trans-African Lineament.  相似文献   

Isotopic composition and origin of polar precipitation in present and glacial climate simulations   总被引：1，自引：0，他引：1  

MARTIN WERNER  MARTIN HEIMANN  GEORG HOFFMANN 《Tellus. Series B, Chemical and physical meteorology》2001,53(1):53-71

The Hamburg atmospheric general circulation model (AGCM) ECHAM‐4 is used to identify the main source regions of precipitation falling on Greenland and Antarctica. Both water isotopes H₂¹⁸O and HDO are explicitly built into the water cycle of the AGCM, and in addition the capability to trace water from different source regions was added to the model. Present and LGM climate simulations show that water from the most important source regions has an isotopic signature similar to the mean isotope values of the total precipitation amount. But water from other source regions (with very different isotopic signatures) contributes an additional, non‐negligible part of the total precipitation amount on both Greenland and Antarctica. Analyses of the temperature‐isotope‐relations for both polar regions reveal a solely bias of the glacial isotope signal on Greenland, which is caused by a strong change in the seasonal deposition of precipitation originating from nearby polar seas and the northern Atlantic. Although the performed simulations under LGM boundary conditions show a decrease of the δ ¹⁸O values in precipitation in agreement with ice core measurements, the AGCM fails to reproduce the observed simultaneous decrease of the deuterium excess signal.  相似文献   

GENTILE IMPRESSIONS OF SALT LAKE CITY,UTAH, 1849–1870*     

MARTIN MITCHELL 《Geographical review》1997,87(3):334-352

ABSTRACT. The landscape of Salt Lake City, Utah, drew considerable comment between 1849 and 1870 from non-Mormon travelers. These experiences, chiefly of overland emigrants, foreign travelers, and military personnel, include first impressions, feelings on entry, and later reactions. The setting, material landscape, Mormon citizenry, and travelers' attitudes toward early Salt Lake City Mormon customs and institutions are discussed.  相似文献