Trends in the Mediterranean rainfall

Summary The trends appearing in the annual rainfall of the 14 selected coastal and island stations of the Mediterranean were invetigated by running 30-year averages. The periods used as well as the standard deviation, the average variability and the coefficient of variation of the annual rainfall are given for each of the 14 stations. It was found that in the majority of the stations upward and downward trends in the annual rainfall appeared but in a few only stations these trends coincide in the same intervals. A relative similarity appeared in the stations of Marseille-Trieste, Malta-Tunis, Gibraltar-Rome, Nicosia-Limassol and Beyrut-Alexandria. By examination of the three more important maxima and minima in the course of rainfall it was observed that many of them coincide simultaneously at about the same time in the different stations and also that these coincidences occurred near the maximum or minimum of sunspots.     

Loess studies in central United States: evolution of concepts

Few words in the realm of earth science have caused more debate than “loess”. It is a common term that was first used as a name of a silt deposit before it was defined in a scientific sense. Because this “loose” deposit is easily distinguished from other more coherent deposits, it was recognized as a matter of practical concern and later became the object of much scientific scrutiny. Loess was first recognized along the Rhine Valley in Germany in the 1830s and was first noted in the United States in 1846 along the lower Mississippi River where it later became the center of attention. The use of the name eventually spread around the world, but its use has not been consistently applied. Over the years some interpretations and stratigraphy correlations have been validated, but others have been hotly contested on conceptual grounds and semantic issues.

The concept of loess evolved into a complex issue as loess and loess-like deposits were discovered in different parts of the US. The evolution of concepts in the central US developed in four indefinite stages: the eras of (1) discovery and development of hypotheses, (2) conditional acceptance of the eolian origin of loess, (3) “bandwagon” popularity of loess research, and (4) analytical inquiry on the nature of loess. Toward the end of the first era around 1900, the popular opinion on the meaning of the term loess shifted from a lithological sense of loose silt to a lithogenetic sense of eolian silt. However, the dual use of the term fostered a lingering skepticism during the second era that ended in 1944 with an explosion of interest that lasted for more than a decade. In 1944, R.J. Russell proposed and H.N. Fisk defended a new non-eolian, property-based, concept of loess. The eolian advocates reacted with surprise and enthusiasm. Each side used constrained arguments to show their view of the problem, but did not examine the fundamental problem, which was not in the proofs of their hypothesis, but in the definition of the term.

Between 1944 and about 1950, the debates about loess reached a maximum level of complexity. The main semantic problem was submersed in peripheral arguments about physical properties and genetic interpretations. The scholarly treatment of the subject by Fisk and Russell stimulated quality responses from a diversity of earth scientists interested in academic and applied studies, particularly geo-history, pedology, soil mechanics and stratigraphy. The long-lasting popularity of loess studies during the bandwagon era lasted to about 1970. By that time, the analytical and technical interests had attracted the mainstream into the fourth era with a focus beyond the old arguments. Although Fisk and Russell found themselves defending an unpopular theory, they stimulated a scientific interest in the late Quaternary history of the Mississippi Valley that may never be exceeded.     

Getting from here to there – energy technology transformation pathways in the EMF27 scenarios

Based on a large number of energy-economic and integrated assessment models, the Energy Modeling Forum (EMF) 27 study systematically explores the implications of technology cost and availability for feasibility and macroeconomic costs of energy system transformations toward climate stabilization. At the highest level, the technology strategy articulated in all the scenarios in EMF27 includes three elements: decarbonization of energy supply, increasing the use of low-carbon energy carriers in end-use, and reduction of energy use. The way that the scenarios differ is in the degree to which these different elements of strategy are implemented, the timing of those implementations, and the associated macroeconomic costs. The study also discusses the value of individual technologies for achieving climate stabilization. A robust finding is that the unavailability of carbon capture and storage and limited availability of bioenergy have the largest impact on feasibility and macroeconomic costs for stabilizing atmospheric concentrations at low levels, mostly because of their combined ability to remove carbon from the atmosphere. Constraining options in the electric sector such as nuclear power, wind and solar energy in contrast has a much smaller impact on the cost of mitigation.     

海相沉积物中的氧化作用和有机质保存:来自富有机碳古沉积物的直接实验证据

什么变量控制着海相沉积物中的有机质(OM)保存是当今生物地球化学研究中的一个最复杂和有争议的问题(Hedges等,1999),使均变论的应用复杂化,即不能简单地用现在的现象去解释过去。具体说,氧化作用在形成富有机碳古沉积物(如地中海腐泥)中扮演一个什么角色一直是人们争论的问题。实验室试验研究了氧对现代沉积物OM降解的影响,研究中主要使用了富碳的海岸沉积物,揭示了除最具反应性的部分之外,在缺氧情况下OM降解过程明显缓慢。然而,在氧化性好、有机质缺乏的深海沉积物中可能有不同的趋势,现在我们仍需要弄清在地质年代中是否缺氧条件增强…     

The influence of central black holes on gravitational lenses

Recent observations indicate that many if not all galaxies host massive central black holes. In this paper we explore the influence of black holes on the lensing properties. We model the lens as an isothermal ellipsoid with a finite core radius plus a central black hole. We show that the presence of the black hole substantially changes the critical curves and caustics. If the black hole mass is above a critical value, then it will completely suppress the central images for all source positions. Realistic central black holes are likely to have masses below this critical value. Even in such subcritical cases, the black hole can suppress the central image when the source is inside a zone of influence, which depends on the core radius and black hole mass. In the subcritical cases, an additional image may be created by the black hole in some regions, which for some radio lenses may be detectable with high-resolution and large dynamic range VLBI maps. The presence of central black holes should also be taken into account when one constrains the core radius from the lack of central images in gravitational lenses.     

Real-time multi-model decadal climate predictions

We present the first climate prediction of the coming decade made with multiple models, initialized with prior observations. This prediction accrues from an international activity to exchange decadal predictions in near real-time, in order to assess differences and similarities, provide a consensus view to prevent over-confidence in forecasts from any single model, and establish current collective capability. We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown. Nevertheless, the forecast systems used here are based on models that have undergone rigorous evaluation and individually have been evaluated for forecast skill. Moreover, it is important to publish forecasts to enable open evaluation, and to provide a focus on climate change in the coming decade. Initialized forecasts of the year 2011 agree well with observations, with a pattern correlation of 0.62 compared to 0.31 for uninitialized projections. In particular, the forecast correctly predicted La Niña in the Pacific, and warm conditions in the north Atlantic and USA. A similar pattern is predicted for 2012 but with a weaker La Niña. Indices of Atlantic multi-decadal variability and Pacific decadal variability show no signal beyond climatology after 2015, while temperature in the Niño3 region is predicted to warm slightly by about 0.5 °C over the coming decade. However, uncertainties are large for individual years and initialization has little impact beyond the first 4 years in most regions. Relative to uninitialized forecasts, initialized forecasts are significantly warmer in the north Atlantic sub-polar gyre and cooler in the north Pacific throughout the decade. They are also significantly cooler in the global average and over most land and ocean regions out to several years ahead. However, in the absence of volcanic eruptions, global temperature is predicted to continue to rise, with each year from 2013 onwards having a 50 % chance of exceeding the current observed record. Verification of these forecasts will provide an important opportunity to test the performance of models and our understanding and knowledge of the drivers of climate change.     

The High-Resolution Coronal Imager (Hi-C)

The High-Resolution Coronal Imager (Hi-C) was flown on a NASA sounding rocket on 11 July 2012. The goal of the Hi-C mission was to obtain high-resolution (≈?0.3?–?0.4′′), high-cadence (≈?5 seconds) images of a solar active region to investigate the dynamics of solar coronal structures at small spatial scales. The instrument consists of a normal-incidence telescope with the optics coated with multilayers to reflect a narrow wavelength range around 19.3 nm (including the Fe xii 19.5-nm spectral line) and a 4096×4096 camera with a plate scale of 0.1′′?pixel^?1. The target of the Hi-C rocket flight was Active Region 11520. Hi-C obtained 37 full-frame images and 86 partial-frame images during the rocket flight. Analysis of the Hi-C data indicates the corona is structured on scales smaller than currently resolved by existing satellite missions.     

Radon emanation from the moon,spatial and temporal variability

Observations of the lunar surface with the orbiting Apollo Alpha Particle Spectrometer during the Apollo 15 and Apollo 16 missions have shown spatial and temporal variations in radon emission. There are a number of well localized features in the spatial distribution of lunar²²²Rn and her daughter²¹⁰Po which apparently correlate with sites of reported transient visual events. There are sources at Aristarchus, Grimaldi and possibly Tsiolkovsky. Activity of²¹⁰Po shows enhancement at most maria edges at rates far in excess of²²²Rn activity. This demonstrates unequivocally the presence of time varying radon activity at the maria edges, taking place at the present time. The increased radon emission is probably caused by sporadic internal activity. In analogy to terrestial processes, radon may be merely a trace component accompanying the release of larger quantities of more common gases to the lunar surface.