A last glacial ice sheet on the Pacific Russian coast and catastrophic change arising from coupled ice–volcanic interaction

Controversy exists over the extent of glaciation in Eastern Asia at the Last Glacial Maximum: complete ice sheet cover vs. restricted mountain icefields (an area discrepancy equivalent to 3.7 Greenland Ice Sheets). Current arguments favour the latter. However, significant last glacial ice-rafted debris (IRD) exists in NW Pacific ocean cores, which must have been sourced from a major ice sheet somewhere bordering the North Pacific. The origin of this IRD is addressed through a combination of marine core analysis, iceberg trajectory modelling and remote sensing of glacial geomorphology. We find compelling evidence for two stages of glaciation centred on the Kamchatka area of maritime southeast Russia during the last glacial, with ice extent intermediate in size between previous maximum and minimum reconstructions. Furthermore, a significant increase in iceberg flux precedes, and accompanies, a substantial marine core ash deposit at around 40ka BP. We speculate that rapid decay of the first stage of the ice sheet may have triggered substantial volcanic activity

Glacial thermohaline circulation states of the northern Atlantic: The compatibility of modelling and observations

We present 3He data froma repeat section across Drake Passage, fromthree sections off the South American continent in the Pacific, at 28?S, 35?S, and 43?S, and fromthree sections in the Atlantic, eastward of the Malvinas, close to 35?W, and near the Greenwich Meridian. In Drake Passage, a distinct high-3He signal is observed that is centered just above the boundary of the Lower and the Upper Circumpolar Deep Water (LCDW, UCDW), and is concentrated towards the northern continental slope. 3He concentrations in the Antarctic Circumpolar Current (ACC) upstream of Drake Passage (World Ocean Circulation Experiment section P19 at 88?W) are markedly lower than those found in Drake Passage, and a regional source of primordial helium in the path of the ACC that might cause the high-3He feature can be ruled out. We explain the feature by addition of high-3He waters present at the 43?S Pacific section. This supports a previous, similar interpretation of a low-salinity anomaly in Drake Passage (Naveira Garabato et al., Deep- Sea Research I 49 (2002) 681), that is strongly related to the high-3He feature. Employing multiparameter water mass analysis (including 3He as a parameter), we find that deep waters as met at the 43?S Pacific section, flowing south along the South American continental slope, contribute substantially to the ACC waters in Drake Passage (fractions exceed 50% locally). Lesser, but laterally more extended contributions are found east of the Malvinas, and still smaller ones are present at 35?W and at the Greenwich Meridian. Using velocity measurements from one of the two Drake Passage sections, we estimate the volume transport of these waters to be 7.071.2 Sv, but the average transport may be somewhat lower as the other realization had a less pronounced signal. The enhanced 3He signature in Drake Passage is essentially confined north of the Polar Front. Further downstreamthe signature crosses this front, to the extent that at 35?W the contributions south and north of it are of similar magnitude. At the same time, the 3He levels north of the front are reduced due to a substantial admixture of low-3He North Atlantic Deep Water, such that 3He becomes highest south of the front. The flow of Southeast Pacific deep slope waters entering the ACC constitutes the predominant exit pathway of the primordial helium released in the deep Pacific, and represents a considerable fraction of the deep water return flow fromthe Pacific into the ACC. Therefore and also because the density range of the added deep slope waters is intermediate between those of UCDW and LCDW, they must be considered a distinct water mass. r 2003 Elsevier Ltd. All rights reserved

The variability of the Atlantic meridional circulation since 1980, as hindcast by a data-driven nonlinear systems model

The Atlantic meridional overturning circulation (AMOC), an important component of the climate system, has only been directly measured since the RAPID array’s installation across the Atlantic at 26°N in 2004. This has shown that the AMOC strength is highly variable on monthly timescales; however, after an abrupt, short-lived, halving of the strength of the AMOC early in 2010, its mean has remained ~ 15% below its pre-2010 level. To attempt to understand the reasons for this variability, we use a control systems identification approach to model the AMOC, with the RAPID data of 2004–2017 providing a trial and test data set. After testing to find the environmental variables, and systems model, that allow us to best match the RAPID observations, we reconstruct AMOC variation back to 1980. Our reconstruction suggests that there is inter-decadal variability in the strength of the AMOC, with periods of both weaker flow than recently, and flow strengths similar to the late 2000s, since 1980. Recent signs of weakening may therefore not reflect the beginning of a sustained decline. It is also shown that there may be predictive power for AMOC variability of around 6 months, as ocean density contrasts between the source and sink regions for the North Atlantic Drift, with lags up to 6 months, are found to be important components of the systems model

Tracking Nonlinear Correlation for Complex Dynamic Systems Using a Windowed Error Reduction Ratio Method

Studying complex dynamic systems is usually very challenging due to limited prior knowledge and high complexity of relationships between interconnected components. Current methods either are like a “black box” that is difficult to understand and relate back to the underlying system or have limited universality and applicability due to too many assumptions. This paper proposes a time-varying Nonlinear Finite Impulse Response model to estimate the multiple features of correlation among measurements including direction, strength, significance, latency, correlation type, and nonlinearity. The dynamic behaviours of correlation are tracked through a sliding window approach based on the Blackman window rather than the simple truncation by a Rectangular window. This method is particularly useful for a system that has very little prior knowledge and the interaction between measurements is nonlinear, time-varying, rapidly changing, or of short duration. Simulation results suggest that the proposed tracking approach significantly reduces the sensitivity of correlation estimation against the window size. Such a method will improve the applicability and robustness of correlation analysis for complex systems. A real application to environmental changing data demonstrates the potential of the proposed method by revealing and characterising hidden information contained within measurements, which is usually “invisible” for conventional methods

Methodology for designing accelerated aging tests for predicting life of photovoltaic arrays

A methodology for designing aging tests in which life prediction was paramount was developed. The methodology builds upon experience with regard to aging behavior in those material classes which are expected to be utilized as encapsulant elements, viz., glasses and polymers, and upon experience with the design of aging tests. The experiences were reviewed, and results are discussed in detail

Introduction: The Laboratory of Nature - Science in the Mountains

"Today I made the ascent of the highest mountain in this region, which for good reasons is called Ventosum, guided only by the desire to see the extraordinary altitude of the place” (Petrarque [1336] 1880, 6-7). Petrarch's ascent of the Mont Ventoux in 1336, or rather his account of it, established the mountain as a distinctive place for experiencing and understanding nature and self. Since then, the mountain has been sought out in increasing numbers by those pursuing spiritual elevation, bodily exertion, and/or scientific investigation. To this day, a pilgrimage church, several hotels, and an observatory are characteristically perched atop Mont Ventoux. And it is famous among cyclists as a legendarily difficult étape of the Tour de Franc

Beyond Rio+20: governance for a green economy

This repository item contains a single issue of the Pardee Center Task Force Reports, a publication series that began publishing in 2009 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.As an intellectual contribution to the preparations for the 2012 United Nations Conference on Sustainable Development (UNCSD, a.k.a. Rio +20), the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future convened a task force of experts to discuss the role of institutions in the actualization of a green economy in the context of sustainable development. A stellar group of experts from academia, government and civil society convened at the Pardee Center and were asked to outline ideas about what the world has learned about institutions for sustainable development from the past, and what we can propose about the governance challenges and opportunities for the continuous development of a green economy in the future. The Task Force members were encouraged to think big and think bold. They were asked to be innovative in their ideas, and maybe even a little irreverent and provocative. They were charged specifically NOT to come to consensus about specific recommendations, but to present a variety and diversity of views. This report presents their thoughts and ideas

Reconstructing El Niño Southern Oscillation using data from ships’ logbooks, 1815–1854. Part II: Comparisons with existing ENSO reconstructions and implications for reconstructing ENSO diversity

© 2017 The Author(s) A systematic comparison of El Niño Southern Oscillation reconstructions during the early to mid-nineteenth century is presented using a range of proxy and documentary sources. Reconstructions of the boreal winter Southern Oscillation Index (SOI) using data from ships’ logbooks presented in a companion paper are evaluated and compared to previous ENSO reconstructions. Comparisons between ENSO reconstructions and the instrumental SOI during a period of overlap (1876–1977) are made. These same proxy and documentary reconstructions are then compared to the logbook-based reconstructions, over 1815–1854. The logbook-based reconstructions compare best with a recent multi-proxy reconstruction that used signals taken from different teleconnection regions, and they have an improved agreement with multi-proxy records compared to a previous attempt to reconstruct the SOI from ships’ logbook data. The logbook-based and the multi-proxy reconstructions are found to capture El Niño events better than La Niña events, and East Pacific El Niño events better than Central Pacific El Niño events, thus suggesting a degree of bias in the historical reconstructions. These findings have important implications for future ENSO reconstructions, with a need for an increased understanding of the effects of different ENSO flavours for future reconstructions

Early-nineteenth-century southern African precipitation reconstructions from ships' logbooks

Atmospheric circulation in the oceans surrounding southern Africa plays an important role in determining its precipitation. This study uses wind information recorded in ships’ logbooks in order to statistically reconstruct summer and winter season precipitation at four southern African weather stations from 1796 to 1854. The reconstruction was obtained by first relating gridded 8° × 8° NCEP-DOE reanalysis seasonal mean wind vectors in the adjacent oceans to station precipitation. Over a 30-year calibration period (1979–2008), significant correlations between wind and precipitation at Cape Town, Mthatha and Royal National Park showed particular correspondence with those areas with the greatest concentration of logbook observations. Principal component regression was used to assess the potential of the dominant patterns of variability in the wind vectors as predictors to reconstruct precipitation. Cross-validation in the calibration period gave confidence that precipitation could be reconstructed at several stations across South Africa, meaning the regression relationships derived in the calibration period could be applied to the gridded seasonal mean logbook data to produce reconstructions of precipitation from 1796 to 1854. The reconstructions show a degree of correspondence with other regional data sets. For instance, the decade beginning in 1810 was the wettest of the period at Mthatha and Royal National Park, while the 1820s were the driest. At Cape Town, the 1820s were the wettest decade, with drier conditions observed in the 1830s. An index of west–east circulation in the summer season revealed correspondence with two documentary reconstructions of El Niño events and increased westerliness, although this did not always result in drier conditions. Attention is also drawn to the remaining 3000 yet to be digitised English East India Company logbooks which would provide a high-resolution picture of atmospheric circulation back to 1700 in the region under consideration

The Pfaffian solution of a dimer-monomer problem: Single monomer on the boundary

We consider the dimer-monomer problem for the rectangular lattice. By mapping the problem into one of close-packed dimers on an extended lattice, we rederive the Tzeng-Wu solution for a single monomer on the boundary by evaluating a Pfaffian. We also clarify the mathematical content of the Tzeng-Wu solution by identifying it as the product of the nonzero eigenvalues of the Kasteleyn matrix.Comment: 4 Pages to appear in the Physical Review E (2006