Global travertine deposition modulated by oscillations in climate

Travertine deposits are important records of past fluid flow in the Earth's crust, and document fluid migration through both tectonic activity and changes in climate. While many studies hint at possible relationships between travertine formation and global climate, none have investigated these connections on a global scale. Here we compile 1649 published travertine ages from six continents to test the hypothesis that global and/or regional changes in climate regulate travertine deposition. Peaks in bedded travertine ages occur with main frequencies that correspond to 100‐kyr changes in global climate, where most peaks occur during glacial terminations or interglacial periods, including a large peak that coincides with the Early Holocene climatic optimum. Time–series analysis also suggests a possible connection with 41‐kyr obliquity cycles. At regional scales, many peaks also correspond with local times of high precipitation or wet conditions. This can be attributed to higher groundwater recharge rates, providing the necessary water to form travertine. Many bedded travertine‐depositing systems may therefore be water‐limiting and sufficient CO₂ may be present even during times of no travertine deposition. Exceptions to this conclusion are banded vein travertine deposits, which typically form during times of dry climate when water tables are low. Copyright © 2019 John Wiley & Sons, Ltd.     

Observations of variable and transient X-ray sources with the Ariel V sky survey experiment

Results obtained during the first six months in orbit of Ariel V with the Leicester Sky Survey are reviewed. Among 80 sources found by a scan of the Milky Way, 16 are new, and 11 UHURU sources in the scanned region are not detected. Some of these sources may be transient. The light curve of Cen X-3 in a binary cycle shows a dip between phase 0.5, and 0.75, and a secondary maximum at the centre of the dip. The dip and the maximum get progressively weaker in the succeeding cycles. These features are interpreted in terms of the stellar wind accretion model. Cyg X-1 observation for 14 days gives a broad minimum around superior conjuction. Four bright transient sources of nova-like light curves have been observed. The light curves and the spectra are given for TrA X-1 (A1524-62) and Tau X-T (A0535+26).Paper presented at the COSPAR Symposium on Fast Transients in X- and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975.     

Variations in the Hydrological Regime of Kara-Bogaz-Gol Gulf,Lake Issyk-Kul,and the Aral Sea Assessed Based on Data of Bottom Sediment Studies

The isotopic and material composition of bottom deposits, examined in the Kara-Bogaz-Gol Gulf, Lake Issyk-Kul, and the Aral Sea, is considered. The obtained data are used to characterize variations in the regime of the water bodies in the Holocene.     

Plant functional traits and microbes vary with position on striped periglacial patterned ground at Glacier National Park,Montana

The retreating snowfields and glaciers of Glacier National Park, Montana, USA, present alpine plants with changes in habitat and hydrology. The adjacent and relic periglacial patterned ground consists of solifluction terraces of green, vegetation-rich stripes alternating with sparsely vegetated brown stripes. We established georeferenced transects on striped periglacial patterned ground for long-term monitoring and data collection on species distribution and plant functional traits at Siyeh Pass and at Piegan Pass at Glacier National Park. We documented species distribution and calculated the relative percent cover (RPC) of qualitative functional traits and used 16S rRNA from soil samples to characterize microbial distribution on green and brown stripes. Plant species distribution varied significantly and there were key differences in microbial distribution between the green and brown stripes. The rare arctic-alpine plants Draba macounii, Papaver pygmaeum, and Sagina nivalis were restricted to brown stripes, where the RPC of xeromorphic taprooted species was significantly higher at the leading edge of the Siyeh Pass snowfield. Brown stripes had a higher percentage of the thermophilic bacteria Thermacetogenium and Thermoflavimicrobium. Green stripes were co-dominated by the adventitiously-rooted dwarf shrubs Salix arctica and the possibly N-fixing Dryas octopetala. Green stripes were inhabited by Krummholz and seedlings of Abies lasiocarpa and Pinus albicaulus. Prosthecobacter, a hydrophilic bacterial genus, was more abundant on the green stripes, which had 6,524 bacterial sequences in comparison to the 1,183 sequences from the brown stripes. While further research can determine which functional traits are critical for these plants, knowledge of the current distribution of plant species and their functional traits can be used in predictive models of the responses of alpine plants to disappearing snowfields and glaciers. This research is important in conservation of rare arctic-alpine species on periglacial patterned ground.

     

Study of on‐site versus off‐site forecasts for Canadian Forces Base Summerside

Abstract

On‐site and off‐site forecasts for the CFB Summerside aerodrome, written coincidentally over a six‐week period, are verified using the Ranked Probability Score and compared by means of a two‐tailed test of paired differences. The results show that, at a 10% level of significance, forecasts made on‐site are significantly better than forecasts made off‐site for at least four hours into the forecast period. When compared with persistence, both forecast offices were superior. At no time did the persistence forecasts score significantly better than those issued by a meteorologist. When compared with climatology, on‐site forecasts were significantly better for the first nine hours, while off‐site forecasts were significantly better for the first ten hours.     

Determining the spatial and temporal patterns of climate changes in China's western interior during the last 15 ka from lacustrine oxygen isotope records

China's western interior is a climatologically complex region, where climatic conditions are primarily controlled by the westerly jet stream and the Asian monsoon system. Observations reveal that the δ¹⁸O signatures of these atmospheric elements as expressed in their meteoric waters are different, and these differences are reflected in the lacustrine systems that are ultimately fed by the meteoric waters. Empirical orthogonal function (EOF) decomposition of 17 lacustrine δ¹⁸O records from this area clearly reveals the spatial and temporal structures of climate changes during the last 15 ka. The first EOF mode, dominated by sites in the NW sector, captures the temperature effect on the variability of the δ¹⁸O dataset. We interpret the variations through time in the amplitude of this mode to be indicative of changes in summer air temperature. The second EOF mode, heavily weighted by sites in the SE sector, reveals the ‘amount effect’ on δ¹⁸O, and thus its amplitude time series indicates changes in the intensity of the Asian summer monsoon. Our EOF‐based reconstructions of regional climate are generally consistent with the δ¹⁸O records of ice cores, cave speleothems and marine carbonates. Copyright © 2008 John Wiley & Sons, Ltd.     

The diffuse cosmic X-ray background spectrum in the 2–10 keV energy range

We report a measurement of the background spectrum based on 10000 counts observed in the energy range 2–10 keV. The rocketborne detector system was optimised for cosmic ray noise rejection. A best fit power law spectrum $$\frac{{dN}}{{dE}} = 16E^{ - 1.8} photons{\text{ }}cm^{ - 2} s^{ - 1} sr^{ - 1} keV^{ - 1} .$$ resulted from the analysis. At 10 keV this result is consistent with recently assessed higher energy data. We show therefore that the change in spectral index between 5 and 50 ke V is approximately ?0.2.     

Local food activity in the Republic of Ireland and Great Britain

Recent changes in local food supply systems have attracted substantial research interest, but little consideration has been paid to exactly where they occur. This article combines data from three studies to compare local food system development in England, Wales, Scotland and Ireland using a single index of food relocalisation, thereby exploring the usefulness of the Index across different social and political contexts. Four diagnostic indicators suggest that local food systems in the south west of Ireland and Britain are particularly well developed. The Index itself is a useful tool for making international comparisons, being easy to replicate and allowing the integration of different data sets. Perhaps its greatest utility is that it opens up new avenues for further research.