Processes governing the predictability of the Atlantic meridional overturning circulation in a coupled GCM

The processes that govern the predictability of decadal variations in the North Atlantic meridional overturning circulation (MOC) are investigated in a long control simulation of the ECHO-G coupled atmosphere?Cocean model. We elucidate the roles of local stochastic forcing by the atmosphere, and other potential ocean processes, and use our results to build a predictive regression model. The primary influence on MOC variability is found to come from air?Csea heat fluxes over the Eastern Labrador Sea. The maximum correlation between such anomalies and the variations in the MOC occurs at a lead time of 2?years, but we demonstrate that the MOC integrates the heat flux variations over a period of 10?years. The corresponding univariate regression model accounts for 74.5% of the interannual variability in the MOC (after the Ekman component has been removed). Dense anomalies to the south of the Greenland-Scotland ridge are also shown to precede the overturning variations by 4?C6?years, and provide a second predictor. With the inclusion of this second predictor the resulting regression model explains 82.8% of the total variance of the MOC. This final bivariate model is also tested during large rapid decadal overturning events. The sign of the rapid change is always well represented by the bivariate model, but the magnitude is usually underestimated, suggesting that other processes are also important for these large rapid decadal changes in the MOC.     

储集层非均质性分析的计算机方法:以西弗吉尼亚州下密西西比系油田为例

本文使用几种计算法和统计法研究美国西弗吉尼亚洲中部格兰尼克里克油田大Ｉｎｊｕｎ砂岩储集层的结构及其与采油量的关系。计算机程序根据已出版的资料编写，以适合（ｌ）计算渗透率对孔隙度的回归；（２）标绘三维孔隙度；（３）确定和标绘根据地球物理测井记录推断的相；（４）估算原始储量、累积产量和采油率。因为回归分析显示出测井记录和岩心孔隙度及岩心渗透率间微弱但重要的相关，所以，孔隙度可用干地层渗透率中以构成储集层的模式。也使用定量地层对比和多维定算法来估算在缺乏可用数据的情况下构造的影响。于井间使用克里格法内插绘制的剖面，突出了孔隙度较高的地带。使用地球物理测井资料和岩心描述，用聚类分析确定导电相。原始储量的估算结果与累计产量数据相结合，得出采油率的估算值。这些采油量变量图通常呈现在岩相图上观察到的相同的南北走向。     

Dammed and diversionary: The multi‐dimensional framing of Brazil's Belo Monte dam

Belo Monte is one of the most divisive dams in Brazilian history, becoming entangled in a thirty‐year struggle between pro‐ and anti‐dam interests over the role of the facility within a complex web of Brazilian development and the future of the Brazilian Amazon. This research explores how the proponents of Belo Monte have adopted a number of policy frames as a means of deflection, to divide the opposition and legitimize the project. It investigates this claim by analyzing speeches given within the Brazilian Câmara dos Deputados and the public speeches of high‐level politicians. These sources, organized around a framework previously identified by Ahlers et al. ( 2014 ), show that the government and individual politicians have used a variety of framing devices to legitimize the hydroelectric facility. Principal methods of framing used also demonstrate how contemporary narratives (e.g. sustainability) have been employed to deflect opposition criticism and widen the scheme's perceived beneficiaries. In doing so, this paper demonstrates how the transformation represented by Belo Monte encompassed not only a process of engineering but also a re‐articulation of the complex and its role in modern Brazil.     

Spaceborne ultraviolet 251–384 nm spectroscopy of a meteor during the 1997 Leonid shower

Abstract— We used the ultraviolet to visible spectrometers onboard the midcourse space experiment to obtain the first ultraviolet spectral measurements of a bright meteor during the 1997 Leonid shower. The meteor was most likely a Leonid with a brightness of about‐2 magnitude at 100 km altitude. In the region between 251 and 310 nm, the two strongest emission lines are from neutral and ionized magnesium. Ionized Ca lines, indicative of a hot T ? 10 000 K plasma, are not detected. The Mg and Mg+ line intensity ratio alone does not yield the ionization temperature, which can be determined only by assuming the electron density. A typical air plasma temperature of T = 4400 K would imply a very high electron density: n_e = 2.2 times 10¹⁸ m‐³, but at chondritic abundances of Fe/Mg and Si/Mg ? 1. For a more reasonable local‐thermodynamic‐equilibrium (LTE) air plasma electron density, the Mg and Mg+ line ratio implies a less than chondritic Fe/Mg = 0.06 abundance ratio and a cool non‐LTE T = 2830 K ionization temperature for the ablation vapor plasma. The present observations do not permit a choice between these alternatives. The new data provide also the first spectral confirmation of the presence of molecular OH and NO emission in meteor spectra.     

The 2dF Galaxy Redshift Survey: the nature of the relative bias between galaxies of different spectral type

We present an analysis of the relative bias between early- and late-type galaxies in the Two-degree Field Galaxy Redshift Survey (2dFGRS) – as defined by the η parameter of Madgwick et al., which quantifies the spectral type of galaxies in the survey. We calculate counts in cells for flux-limited samples of early- and late-type galaxies, using approximately cubical cells with sides ranging from 7 to  42 h ⁻¹ Mpc  . We measure the variance of the counts in cells using the method of Efstathiou et al., which we find requires a correction for a finite volume effect equivalent to the integral constraint bias of the autocorrelation function. Using a maximum-likelihood technique we fit lognormal models to the one-point density distribution, and develop methods of dealing with biases in the recovered variances resulting from this technique. We then examine the joint density distribution function,   f (δ_E, δ_L)  , and directly fit deterministic bias models to the joint counts in cells. We measure a linear relative bias of ≈1.3, which does not vary significantly with ℓ. A deterministic linear bias model is, however, a poor approximation to the data, especially on small scales  (ℓ≤ 28  h ⁻¹ Mpc)  where deterministic linear bias is excluded at high significance. A power-law bias model with index   b ₁≈ 0.75  is a significantly better fit to the data on all scales, although linear bias becomes consistent with the data for  ℓ≳ 40  h ⁻¹ Mpc  .     

Characterizing Atmospheric Aerosols off the Atlantic Canadian Coast During C-FOG

Boundary-Layer Meteorology - Marine aerosols play an important role in the Earth’s climate, but their effects remain highly uncertain due to a poor understanding of their sources, properties,...