ENSO to multi-decadal time scale changes in East Australian Current transports and Fort Denison sea level: Oceanic Rossby waves as the connecting mechanism     

Neil J Holbrook  Ian D GoodwinShayne McGregor  Ernesto MolinaScott B Power 《Deep Sea Research Part II: Topical Studies in Oceanography》2011,58(5):547-558

The connection between East Australian Current (EAC) transport variability and Australia’s east coast sea level has received little treatment in the literature. This is due in part to the complex interacting physical processes operating in the coastal zone combined with the sparsity of observations available to improve our understanding of these possible connections. This study demonstrates a statistically significant (at the >90% level) relationship between interannual to decadal time scale variations in observed estimates of the EAC transport changes and east coast sea level measured at the high-quality, long record Fort Denison tide-gauge in Sydney Harbour, Australia (33°51′18″S, 151°13′32″E). We further demonstrate, using a linear reduced-gravity ocean model, that ENSO to decadal time-scale variations and the ocean-adjusted multi-decadal trend (approx. 1 cm/decade) in observed sea level at Fort Denison are strongly connected to modulations of EAC transports by incoming westward propagating oceanic Rossby waves. We show that EAC transport and Fort Denison sea level vary in a manner expected from both Tasman Sea generated Rossby waves, which account for the interannual and multi-annual variability, and remotely forced (from east of New Zealand) Rossby wave connections through the mid-latitudes, accounting for the ocean-adjusted multi-decadal trend observed at the New South Wales coast - with the regional-Tasman Sea forcing explaining the greatest overall proportion of EAC transport and sea-level variances.  相似文献   

A potential flood hazard caused by Tianchi volcano eruption in Changbai Mountain, Northeast China   总被引：1，自引：0，他引：1  

Kunshan Bao  Guoping Wang  Xianguo Lu  Neil B. McLaughlin 《山地科学学报》2011,8(5):677-681

Geohazards appear to be increasing in frequency globally. it is of necessity to actively manage these natural hazards to minimize loss of life and property. from an early warning perspective, this paper stresses the potential fatal flood hazard represented by the huge volume of water in tianchi lake, the unique geography of changbai mountain, and the limited flood control ability in the upstream of the songhua river. northeast asian countries should keep a watchful eye on the changbai volcano cooperatively, and chinese government especially needs to prepare plans for fighting a flood in advance.  相似文献   

Sediment accumulation rates in European lakes since AD 1850: trends,reference conditions and exceedence     

Neil L. Rose  David Morley  Peter G. Appleby  Richard W. Battarbee  Tiiu Alliksaar  Piero Guilizzoni  Erik Jeppesen  Atte Korhola  Jaan-Mati Punning 《Journal of Paleolimnology》2011,45(4):447-468

Sediment accumulation rate (SAR) is an important physical parameter in all lakes and increases have been observed in many over the last c.100 years. This has been ascribed to changes in land-use and land-management causing accelerated catchment soil erosion and an increase in autochthonous organic matter production. The EU Water Framework Directive requires that assessment of biological, hydromorphological and chemical elements of water quality should be based on the degree to which present day conditions deviate from those expected in the absence of significant anthropogenic influence, termed reference conditions. Currently however, the reference condition for sediment accumulation rate for lakes of different types is undefined. To improve our understanding of the controls on SARs we compiled SAR and lake typology data for 207 European lakes derived from ²¹⁰Pb dated cores to assess how rates have changed through time (in 25 year classes) both overall and for lakes of different types. Seventy-one percent of these sediment cores showed surface SARs higher than “basal” (mainly nineteenth century) rates, 11% showed no change while 18% showed a decline. Lakes were then classified into lake-types using four variables: alkalinity (3 classes), altitude (3 classes), maximum depth (2 classes) and lake area (2 classes). This generated a possible 36 lake classes of which 25 were represented in the dataset. Nine lake-types contained >10 lakes. Little change in SAR occurred prior to 1900 and most increases occurred in more recent periods, in particular 1950–1975 and post-1975. This indicates a general acceleration in SAR in European lakes during the second half of the twentieth century. Reference SARs were estimated for six lake-types with the highest number of sites. European mountain lakes had the lowest reference SAR (0.005 ± 0.003 g cm⁻² yr⁻¹) while lowland, high alkalinity sites had the highest (0.03–0.04 g cm⁻² yr⁻¹). SARs for other lake-types ranged between 0.012 and 0.024 g cm⁻² yr⁻¹. Using the mountain lake-type as an example, the 1850 reference SAR appears to show good agreement with available data for lakes beyond Europe indicating these values may be more broadly applicable. Contemporary SARs in lakes of all classes showed exceedence over their defined reference SAR. This may be partly due to diagenetic processes. Greatest exceedences were found in shallow, low altitude lakes and these are considered to be the ones under the greatest threat from continued elevation of SAR. It is considered that climate change may play a progressively more important role in driving SAR in the future.  相似文献   

Paleoclimate record in the Nubian Sandstone Aquifer,Sinai Peninsula,Egypt     

Abdou Abouelmagd  Mohamed Sultan  Neil C. Sturchio  Farouk Soliman  Mohamed Rashed  Mohamed Ahmed  Alan E. Kehew  Adam Milewski  Kyle Chouinard 《Quaternary Research》2014

Sixteen groundwater samples collected from production wells tapping Lower Cretaceous Nubian Sandstone and fractured basement aquifers in Sinai were analyzed for their stable isotopic compositions, dissolved noble gas concentrations (recharge temperatures), tritium activities, and ¹⁴C abundances. Results define two groups of samples: Group I has older ages, lower recharge temperatures, and depleted isotopic compositions (adjusted ¹⁴C model age: 24,000–31,000 yr BP; δ¹⁸O: − 9.59‰ to − 6.53‰; δ²H: − 72.9‰ to − 42.9‰; < 1 TU; and recharge T: 17.5–22.0°C) compared to Group II (adjusted ¹⁴C model age: 700–4700 yr BP; δ¹⁸O: − 5.89‰ to − 4.84‰; δ²H: − 34.5‰ to − 24.1‰; < 1 to 2.78 TU; and recharge T: 20.6–26.2°C). Group II samples have isotopic compositions similar to those of average modern rainfall, with larger d-excess values than Group I waters, and locally measurable tritium activity (up to 2.8 TU). These observations are consistent with (1) the Nubian Aquifer being largely recharged prior to and/or during the Last Glacial Maximum (represented by Group I), possibly through the intensification of paleowesterlies; and (2) continued sporadic recharge during the relatively dry and warmer interglacial period (represented by Group II) under conditions similar to those of the present.  相似文献   

Archaeological exploration using magnetic and GPR methods at the first court of Hatshepsut Temple in Luxor, Egypt     

Hatem Odah  Ahmed Ismail  Ibrahim Elhemaly  Neil Anderson  Abbas M. Abbas  Fathy Shaaban 《Arabian Journal of Geosciences》2013,6(3):865-871

The Hatshepsut Temple at Luxor, southern Egypt was built as a garden for Amun, and the first court indeed had exotic trees and vegetations. The pathway to the temple was along a sphinx-lined causeway linking the valley to pylons, which are missing now. As an effort to outline remains of the vanished garden and missing pylons and any other possible archaeological structures at this first court site, an extensive integrated magnetic/ground-penetrating radar (GPR) geophysical survey was conducted. The magnetic survey covered the entire area of the first court (100?×?60 m), while the GPR survey covered only an area of 50?×?50 m. The acquired GPR data were processed and presented as 2-D depth sections providing a reasonable vertical/horizontal resolution for the upper 6 m of the investigated site. The acquired magnetic data was processed and presented as 2-D image. The integrated interpretation of the acquired GPR and magnetic data revealed some archaeological features including a rectangular depression which is presumably an ancient man-made pond in the garden of the temple, a rectangular feature that may be a foundation of the missing pylon of the temple, and a suite of aligned anomalies that could be the remnants of sphinx. Such findings reflect the archaeological potentiality of the surveyed site and outline the extension of the temple. Meanwhile, these results necessitate further geophysical investigation or archaeological excavation to be confirmed.  相似文献   

Spatial and temporal variability of flood seasonality in Wales     

Neil Macdonald  Ian D. Phillips  Gareth Mayle 《水文研究》2010,24(13):1806-1820

High‐magnitude floods across Europe within the last decade have resulted in the widespread reassessment of flood risk; this coupled with the introduction of the Water Framework Directive (2000) has increased the need for a detailed understanding of seasonal variability in flood magnitude and frequency. Mean day of flood (MDF) and flood seasonality were calculated for Wales using 30 years of gauged river‐flow records (1973–2002). Noticeable regional variations in timing and length of flood season are evident, with flooding occurring earlier in small catchments draining higher elevations in north and mid‐west Wales. Low‐altitude regions in West Wales exposed to westerly winds experience flooding during October–January, while large eastern draining catchments experience later flooding (January–February). In the northeast and mid‐east regions December–January months experience the greatest number of floods, while the southeast has a slightly longer flood season (December–February), with a noticeable increase in January floods. Patterns obtained from MDF data demonstrate their effectiveness and use in analysing regional patterns in flood seasonality, but catchment‐specific determinants, e.g. catchment wetness, size and precipitation regime are important factors in flood seasonality. Relatively strong correlations between precipitation and flood activity are evident in Wales, with a poorer relationship between flooding and weather types and the North Atlantic Oscillation (NAO). Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

On the formation of Hα line emission around classical T Tauri stars     

Ryuichi Kurosawa  Tim J. Harries  Neil H. Symington 《Monthly notices of the Royal Astronomical Society》2006,370(2):580-596

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X-ray and γ-ray spectra and variability of the black hole candidate GX 339–4     

Grzegorz Wardzi&#;ski  rzej A. Zdziarski  Marek Gierli&#;ski  J. Eric Grove  Keith Jahoda  W. Neil Johnson 《Monthly notices of the Royal Astronomical Society》2002,337(3):829-839

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On the fate of gas in ultraluminous infrared galaxies at low and high redshift     

Neil Trentham 《Monthly notices of the Royal Astronomical Society》2001,323(3):542-546

It is often suggested that the distant galaxies recently identified in 850-μm surveys with the SCUBA bolometer array on the James Clerk Maxwell Telescope are high-redshift analogues to local ultraluminous infrared galaxies, based on their similar spectral energy distributions and luminosities. We show that these two populations of objects must differ in at least one fundamental way from each other. This assertion is based on a consideration of the possible fates of gas in the high-redshift SCUBA galaxies, given the requirement that they most evolve into some subset of the low-redshift galaxy population with a comoving density of about 10⁻⁴ Mpc⁻³. One possibility is that the SCUBA galaxies have similar gas density profiles to local ultraluminous galaxies. If this is the case, then they must derive almost all their power from active galactic nuclei, which appears not to be the case for local ultraluminous galaxies, which are predominantly star-formation-powered. Another possibility is that the SCUBA galaxies have more extended gas density profiles than local ultraluminous galaxies. In this case they must be almost all star-formation-powered, and much of the star formation in the Universe can happen in these objects. Either way there is a significant difference between the low- and high-redshift populations.  相似文献   

The spatial and kinematic distributions of cluster galaxies in a ΛCDM universe: comparison with observations     

Antonaldo Diaferio  Guinevere Kauffmann  Michael L. Balogh  Simon D. M. White  David Schade  Erica Ellingson † 《Monthly notices of the Royal Astronomical Society》2001,323(4):999-1015

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