Subsurface flow measurements using passive flux meters in variably-saturated cold-regions landscapes     

Élise G. Devoie  Ryan F. Connon  James R. Craig  William L. Quinton 《水文研究》2020,34(23):4541-4546

To date, passive flux meters have predominantly been applied in temperate environments for tracking the movement of contaminants in groundwater. This study applies these instruments to reduce uncertainty in (typically instantaneous) flux measurements made in a low-gradient, wetland dominated, discontinuous permafrost environment. This method supports improved estimation of unsaturated and over-winter subsurface flows which are very difficult to quantify using hydraulic gradient-based approaches. Improved subsurface flow estimates can play a key role in understanding the water budget of this landscape.  相似文献   

Snowpack disrupts relationship between young water fraction and isotope amplitude ratio; approximately one fifth of mountain streamflow less than one year old     

Éowyn M. S. Campbell  Igor Pavlovskii  M. Cathryn Ryan 《水文研究》2020,34(25):4762-4775

Previous “fraction of young water” (F_yw) estimates based on relative annual isotopic amplitudes in precipitation (A_p) and streamflow (A_s) produced low F_yw values in mountain catchments, which is contrary to extensive research that reports rapid water transmission in mountains. This study investigated this discrepancy by testing the effect of snow accumulation on the model that underpins the F_yw method. A Monte-Carlo analysis of simulations for 20,000 randomly-generated catchment model configurations used 10 years of precipitation inputs for the Upper Elbow River catchment in the Rocky Mountains (Alberta, Canada) to model discharge with and without snowpack storage of winter precipitation. Neither direct nor modified precipitation input produced a 1:1 relationship between A_s/A_p and F_yw, undermining the applicability of the original F_yw method in mountain watersheds with large seasonal snow accumulation. With snowpack-modified input a given A_s/A_p ratio corresponds to a range of F_yw values, which can still provide semi-quantitative information. In the small (435 km²) Elbow River catchment a F_yw range of 7–23% supports previous findings of rapid transmission in mountain catchments. Further analysis showed that the improved discharge prediction (Nash–Sutcliffe efficiency > 0.9) correlates with higher F_yw values and demonstrated that the interannual shifts in δ¹⁸O can be used to estimate of new water (<1 year) fraction in winter streamflow, and the estimate of 20% for the Elbow River further supports rapid transmission in mountain catchments.  相似文献   

A Middle Palaeolithic site in the southern North Sea: investigating the archaeology and palaeogeography of Area 240          下载免费PDF全文

L. TIZZARD  A. R. BICKET  J. BENJAMIN  D. DE LOECKER 《第四纪科学杂志》2014,29(7):698-710

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Paleoenvironments during Younger Dryas‐Early Holocene retreat of the Greenland Ice Sheet from outer Disko Trough,central west Greenland          下载免费PDF全文

ANNE E. JENNINGS  MARIAH E. WALTON  COLM Ó COFAIGH  AOIBHEANN KILFEATHER  JOHN T. ANDREWS  JOSEPH D. ORTIZ  ANNE DE VERNAL  JULIAN A. DOWDESWELL 《第四纪科学杂志》2014,29(1):27-40

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孟加拉湾超级风暴费林对西藏强降水的影响分析     

德庆  徐珺  宗志平  赤曲  罗布坚参  代华光 《气象》2015,41(9):1086-1094

利用NCEP/NCAR(2.5°×2.5°)再分析资料和常规、非常规观测资料,通过环境场和中尺度特征较全面细致地分析了孟加拉湾风暴费林（Phailin）对西藏特大暴雪的影响。研究表明：“费林”对强降水的影响主要是登陆减弱为低压后,低压云系分两个阶段形成三个中尺度对流云团,对流云团在南支槽的作用下上高原。而强降水的发生和南风风速的大小有直接的对应关系,西南低空急流建立后西藏南部才出现强降水,而低空急流的建立是靠南支槽的贡献。南风风速和强降水的这一重要关系为此类天气提供了预报着眼点。  相似文献   

Sumixam maximus gen. and sp. nov., a New Pennsylvanian Species of Archaeorthoptera (Neoptera; Indiana, USA)     

Olivier BéTHOUX  Christin GROSSMANN 《《地质学报》英文版》2011,85(3):515-520

A new Mazon-Creek-type fossil specimen is described as Sumixam maximus gen. and sp. nov., assigned to the taxon Archaeorthoptera Béthoux and Nel, 2002 (composed of Orthoptera and some fossil relatives): it exhibits one of the diagnostic character states of this taxon, which is the fusion of CuA (emerging from M + CuA) with CuP, or a branch of it. A more precise taxonomic assignment is out of reach. The new taxon exhibits a fusion of the anterior branch of MA with RP, and a point of divergence of MA and MP located near the point of divergence of CuA (from M + CuA), but lack a branching of CuPa. This unique combination of character states is probably derived with respect to a number of contemporaneous species. Sumixam maximus gen. and sp. nov. is most likely the closest known relative of the panorthopterans, which include all the recent Archaeorthoptera.  相似文献   

GROUND THERMAL CONDITIONS AT CHACHANI VOLCANO,SOUTHERN PERU     

NURIA ANDRÉS  DAVID PALACIOS  JOSE ÚBEDA  JESÚS ALCALÁ 《Geografiska Annaler: Series A, Physical Geography》2011,93(3):151-162

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Identifying the accidental-natural mortality of leporids in the archaeological record: insights from a taphonomical analysis of a pitfall without evidence of human presence     

Maxime Pelletier  Emmanuel Desclaux  Jean-Baptiste Mallye  Evelyne CrÉgut-Bonnoure 《第四纪科学杂志》2020,35(5):677-694

Leporids (Lagomorpha, Mammalia), especially the mountain hare (Lepus timidus) and the European rabbit (Oryctolagus cuniculus), have been among the most abundant small game in western Europe since the Pleistocene. These animals are preferred prey for more than 40 predators, which increases the chances of finding their skeletal remains at archaeological or natural sites, and in particular karstic formations alternately occupied by Palaeolithic human societies and other predators. Moreover, specific eco-ethological characteristics for both species also offer the possibility to produce a substantial quantity of their bones accumulated by natural mortality without predation, making it more difficult to identify their origin in the fossil record. Despite this fact, the taphonomic signature of accidental-natural accumulations of leporids in karsts, such as pitfalls, has never been properly characterised. In order to address these issues, we carried out a detailed taphonomic study of leporid remains in a pitfall without any evidence of human activity, namely at Coulet des Roches (Monieux, Vaucluse, south-eastern France). At this site, leporids are the most abundant species throughout the Last Glacial Maximum sedimentary sequence. The bone accumulation was analysed in order to determine the most relevant criteria to identify a natural accumulation that results from the accidental fall of individuals in the pitfall. The relative proportions of each species are consistent with their current ethology, and their mortality profiles are compatible with the structure of a living natural population. The completeness rate of the different skeletal portions for both species is relatively high, bones are less fragmented and, unlike what might be expected, very few anatomical connections were preserved. The observed anatomical representation, breakage, and bone surface modification patterns are discussed and compared with available data concerning accumulations with predation. Taken together, the identified criteria contribute valuable help in the recognition of accidental mortality in the fossil record, as well as to evaluate the proportion of leporid bones accumulated naturally and those accumulated by predation, human or not, in a deposit.  相似文献   

A shift towards wetter and windier conditions in southern Sweden around the prominent solar minimum 2750 cal a BP          下载免费PDF全文

ANETTE MELLSTRÖM  NATHALIE VAN DER PUTTEN  RAIMUND MUSCHELER  RIXT DE JONG  SVANTE BJÖRCK 《第四纪科学杂志》2015,30(3):235-244

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Potential seasonal calibration for palaeoenvironmental reconstruction using skeletal microstructures and strontium measurements from the cold‐water coral Lophelia pertusa          下载免费PDF全文

VINCENT MOUCHI  QUENTIN G. CROWLEY  ANDREW L. JACKSON  FRANK MCDERMOTT  XAVIER MONTEYS  MARC DE RAFÉLIS  JOSÉ LUIS RUEDA  FRANCK LARTAUD 《第四纪科学杂志》2014,29(8):803-814

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