Probabilistic seasonal streamflow forecasts of the Citarum River,Indonesia, based on general circulation models

In this study we discuss probabilistic forecasts of Citarum River streamflow, which supplies 80 % of the water demands in Jakarta, Indonesia, based on general circulation model (GCM) output, for the September–November (SON) season. Retrospective forecasts of precipitation made over the period 1982–2010 with two coupled-ocean atmosphere GCMs, initialized in August, are used in conjunction historical streamflow records, with a cross-validated regression model. Pearson’s product moment correlation skill values of 0.58–0.67 are obtained, with relative operating characteristic scores of 0.67–0.84 and 0.74–0.92 for the lower and upper tercile categories of flows respectively. Both GCMs thus demonstrate promising ability to forecast below/above normal streamflow for the Citarum River flow during the SON season.     

Metabolic loss of mass in glass eels at different salinities according to their propensity to migrate

Eel facultative catadromy is not clearly understood. Initial work suggested a possible control by energy content and energy expense in young stages. The present work aimed to better understand the mechanisms involved, by studying the influence of the salinity rearing environment in the loss of mass and therefore on fish energy and migration. Glass eels (Anguilla anguilla L.) caught on the Atlantic coast were identified according to their rheotactic response to the dusk signal, and thus to their propensity to migrate which can be low (sedentary, M⁻ fish) or high (flow-wise catches in early night, M⁺ fish). M⁺ and M⁻ fish were individually placed at different salinities (0, 10 or 30) for 28 days in small containers equipped with shelters. Individual wet mass and pigmentary stage were determined on Day 1 and Day 28. In addition, dry mass and percent dry mass were measured on a sub-sample of 30 fish randomly chosen on Day 1, and on all fish on Day 28. There was no difference in the loss of mass linked to their adaptation to salinity between M⁻ and M⁺ fish, and so the results do not support the link between migratory behaviour and salinity tolérance (or to a larger extent osmoregulation). However, M⁻ fish lost more wet mass than M⁺ fish irrespective of the salinity, maybe because of a higher standard metabolism, which suggests that glass eels prone to loose more energy might choose to settle at sea or in estuary. In addition, the highest percent dry mass after 28 days in seawater associated to the highest loss of mass in 28 days in seawater does not support a higher energy cost of osmoregulation at sea.     

Non-destructive,high-resolution X-ray micro-CT of a Hairy Stalagmite: investigating the structural details of a biogenic speleothem

Three-dimensional X-ray micro-computed tomography permits to investigate the internal structure of objects at a high resolution without altering its original form. It also facilitates the rendering and visualization of a virtual replica, which can be subjected to rigorous and complex analyses. In the present study, micro-computed tomography was used to investigate a unique and fragile speleothem (cave formation) named a “Hairy Stalagmite”. Non-destructive analyses have revealed the calcareous internal structure of this speleothem, which consists of hollow, interconnected tubes. Rendered two-dimensional cross-sections also clearly revealed the outline of a once dense root nest that formed part of the speleothem’s biogenic origin. The internal structure was further visualized using an image sequence of two-dimensional cross-sections to create a video that “brings the speleothem to life”, also illustrating its complexity and variability. Statistical analyses revealed structural variability in void fraction, which is likely related to changing environmental conditions. In addition, the micro-computed tomography data were used as input for additive manufacturing (three-dimensional printing) in order to produce an enlarged replica of the Hairy Stalagmite sample, which made physical inspection possible. This combined approach represents the first of its kind and provides much benefit for future studies.     

近百年里海海平面的升降与伏尔加三角洲的发育

位于里海北部的伏尔加三角洲属河控型三角洲，其水下坡度极度平缓。近百年来里海海平面升降幅度达3．46m，其变化可分为3个阶段：1900－1929年缓慢下降期，平均下降速率为1.1cm/a；1930－1977年快速下降期，平均速率为6.3cm/a；1978－1999年为快速上升期，平均上升速率达到8.8cm/a。在海平面下降阶段，伏尔加三角洲增长幅度达到每年2－180km^2，这是由于河流泥沙的沉积和浅水区出露水面而造成。海平面上升之时，较浅水下三角洲部分成为“缓冲带”，降低了海平面上升对三角洲的影响。尽管近20多年来海平面迅速上升，伏尔加三角洲并未发现海岸侵蚀、湿地损失、盐水入侵、海岸洪涝灾害等一般大河三角洲常见的现象。对比其它三角洲可以发现，各个大河三角洲各以不同的方式响应海平面的上升。     

Interannual variability of the upper layer of the tropical Atlantic Ocean from in situ data between 1979 and 1999

Interannual variability of the upper layers of the tropical Atlantic is described based on in situ data. An objective analysis used all available temperature observations of the upper tropical Atlantic between 1979 and 1999 to construct a 4D database. Wind data are used to investigate potential mechanisms which might explain the observed variability. Four remarkable events are described: 1983–1984, 1988–1990, 1994–1995 and 1997–1998. Three of them are characterised as equatorial (1983–1984, 1994–1995, and 1997–1998). The 1988–1990 event is a basin-wide phenomenon which does not involve the same mechanisms as the other three. Results of statistical decomposition in empirical orthogonal functions (EOFs) are discussed. There is no evidence of an inter-hemispheric mode on the depth of the 20?°C-isotherm (D20) and heat content comparable to the observed mode for sea surface temperature (SST) fields. Most energetic patterns for D20 and heat content are dominated by the stronger variability in the northern part of the basin. Influences of other climate signals are investigated. Correlations between the winter NAO (North Atlantic Oscillation) index and our standard variables is marginally significant. A positive NAOW (North Atlantic Oscillation of Winter) is associated with SST cooling in a latitude band between 10°N and 20°N. When applied to the El-Niño index, correlations are much more significant. We found two scales of maximum correlation: at the four month lag after the El-Niño mature phase when the thermocline slope and zonal heat content gradient are maximum along the equator, and at the ten month lag after the mature phase of El-Niño when the thermocline slope weakens and the equatorial gradient of heat content vanished. The correlation with a zonal wind index (average between 30°W–35°W and 2°N–2°S) has been computed. Correlation is maximum at the six month lag when the thermocline slope and the zonal heat content gradient are maximum in the equatorial band. This “Atlantic Niño” mode is influenced by the Pacific Ocean's variability and reaches a maximum one year after a warm event in the eastern Pacific.     

海南抱板金矿田围岩蚀变带中绿泥石的特征及其意义

通过对海南抱板金矿田围岩蚀变带中绿泥石成分的分析，讨论了蚀变带中绿泥石的成分变化，并由此确定围岩蚀为形成于２９０～３００℃和氧逸度为１０＾－２６～１０＾－３４的条件下，结合含金石英脉的体包裹体研究，从蚀变到成矿物质沉淀，热液的温度和氧逸度是变化的。     

Physical impact of grazing by sheep on soil parameters in the Nama Karoo subshrub/grass rangeland of South Africa

The direct short-term impact of three rates of stocking (4, 8 and 16 small-stock units [SSU] ha^?1) was quantified in terms of soil characteristics of arid Nama Karoo vegetation (subshrub/grass). Mature Merino wethers grazed in the experimental plots throughout May in 1995 and 1996 (the plots were not subjected to grazing at any other time). Stocking rate proved inversely related to initial infiltration rate. Light trampling (4 SSU ha^?1) loosened the topsoil sufficiently to increase the initial infiltration rate: infiltration capacity of soil in fields stocked at 4 SSU ha^?1 and 16 SSU ha^?1 was 17% higher and 14% lower respectively than that of soil of ungrazed rangeland over the two grazing periods. Increased soil compaction and greater bulk density due to higher stocking rates significant decreased the infiltration rate. Compared to ungrazed rangeland stocking rates of 4, 8 and 16 SSU ha^?1 over the two grazing periods increased bulk density respectively by 2.73%, 6.67% and 8.945% and compaction by 10.90%, 16.78% and 20.90%. No grazing also increased bulk density and soil compaction and decreased infiltration rate. Light stocking (4 SSU ha^?1) influenced all soil parameters most favourably. From a hydrologic point of view, grazing levels and rotation schemes need to be tailored for sustainable utilization of arid subshrub/grass vegetation by livestock.     

粘弹介质本构理论讨论

阐述了建立物质本构关系时应满足的基本公理,较详细地推导了各种类型粘弹性物质的本构关系,论述了变率理论与泛函数论之间的关系,推导了对于粘弹性问题求解具有实用意义的对应定理,并以简单的例子说明对应定理的应用。     

Comparison between modelling and measurement of marine dispersion,environmental half-time and 137Cs inventories after the Fukushima Daiichi accident

Contamination of the marine environment following the accident at the Fukushima Daiichi nuclear power plant (FDNPP) represents the most important influx of artificial radioactivity released into the sea ever recorded. The evaluation, in near real time, of the total amount of radionuclide released at sea and of the residence time in coastal waters were ones of challenges for nuclear authorities during this event. In the framework of a crisis situation, a numerical hydrodynamical model has been built and used ‘as is’. The concomitant use of this numerical model and in situ data allows the comparison of the simulated and measured environmental half-times. A tuning of the wind drag coefficient has been nevertheless necessary to reproduce the evolution of measured inventories of ¹³⁷Cs and ¹³⁴Cs between April and June 2011. After tuning, the relative mean absolute error between measured and simulated concentrations for the 849 measurements in the dataset is 69 %, while the relative bias indicates a model underestimation of 4 %. These results confirm the estimates of the source term, i.e. 27 PBq (12–41 PBq) for direct releases and 3 PBq for atmospheric deposition onto the sea. The parameters applied here to simulate atmospheric deposition onto the sea are within the correct order of magnitude for reproducing seawater concentrations. Quantitative inventories of tracers which integrate dispersion and transport processes are useful to test model reliability. It exhausts the model sensibility to meteorological forcing, which remains difficult to appraise to reproduce mid- to long-term transport.     

Tepee structures and associated diagenetic features in intertidal carbonate sands (lower Jurassic,Morocco)

In southeastern Morocco, Early Jurassic inter- to supratidal carbonates can be followed for 200–300 km along the southern slopes of the High Atlas mountains. These beds form intervals of several tens to more than one hundred metres.Tepee structures, which are common in these beds, are confined to coarse-grained, early lithified beaches. Comparison with similar features in the Recent, and analysis of the diagenetic history of the sheetcrack-fills suggests that the formation of the tepees is an early, almost synsedimentary event.