Linking large-parallax Spitzer–CFHT–VLT astrometry of asteroids

We show that the new ephemeris-space multiple-address-comparison (eMAC) method solves asteroid linking problems despite large parallaxes by applying the method to astrometric asteroid observation sets obtained nearly simultaneously with the Spitzer space telescope, the Canada–France–Hawaii Telescope (CFHT), and European Southern Observatory's Very Large Telescope (VLT). For main-belt asteroids, the parallax between Spitzer and the Earth-based telescopes is approximately one degree which is large as compared to a typical parallax for solely Earth-based telescopes in the arcseconds regime. In the eMAC method, we reduce the initially huge amount of possible linkages between observation sets by comparing samples of ephemerides that have been computed separately for all sets at, say, three common dates. If the non-zero ephemeris probability densities overlap at all common dates, we try to find an orbit solution for these so-called trial linkages. If there exists an orbit which reproduces all the astrometric observations assuming predefined observational errors, we call it a linkage. Known asteroids are independently identified among Spitzer, CFHT, and VLT astrometry, and comparing the identified observations to the linkages found shows that the method found all known correct linkages present in the data. In addition, we also found five previously unpublished linkages between Spitzer astrometry and Earth-based astrometry. Based on our simulations, we found virtually all Spitzer-related linkages between two single-night observation sets, and more than 99.4% of linkages between two single-night observation sets obtained by Earth-based observatories. Virtually all correct linkages consisting of at least three single-night sets were also detected. The results show that large-parallax discovery observations made from a spacecraft can be linked to Earth-based follow-up observations to ensure that the objects are not lost. Furthermore, we compute the heliocentric and Spitzer-centric distances as well as the corresponding solar phase angles at the dates of Spitzer observations. Based on comparisons to simulated geocentric observations, we also show that, for typical nearly-simultaneous observations, the parallax reduces the distance uncertainties by several orders of magnitude.     

Evidence of chromosomal damage in common eiders (Somateria mollissima) from the Baltic Sea

Common eiders nesting in the Baltic Sea are exposed to generally high levels of contaminants including potentially genotoxic polycyclic aromatic hydrocarbons and organochlorines. Blood samples were collected from eiders at eight sites in the Baltic Sea and two sites in the Beaufort Sea. DNA content variation was estimated using the flow cytometric method, and subsequently utilized as a biomarker of genetic damage. We observed no significant differences in genetic damage among populations within either the Baltic or Beaufort Seas. However, eider populations from the Baltic Sea had significantly elevated estimates of genetic damage compared to populations from the Beaufort Sea.     

Air–Sea \mathrm{CO}_{2} Gas Transfer Velocity in a Shallow Estuary

The air–sea transfer velocity of $\mathrm{CO}_{2}\, (k_{\mathrm{CO}_{2}})$ was investigated in a shallow estuary in March to July 2012, using eddy-covariance measurements of $\mathrm{CO}_{2}$ fluxes and measured air–sea $\mathrm{CO}_{2}$ partial-pressure differences. A data evaluation method that eliminates data by nine rejection criteria in order to heighten parametrization certainty is proposed. We tested the data evaluation method by comparing two datasets: one derived using quality criteria related solely to the eddy-covariance method, and the other derived using quality criteria based on both eddy-covariance and cospectral peak methods. The best parametrization of transfer velocity normalized to a Schmidt number of 600 $(k_{600})$ was determined to be: $k_{600} = 0.3\,{U_{10}}^{2.5}$ where $U_{10}$ is the wind speed in m $\mathrm{s}^{-1}$ at 10 m; $k_{600}$ is based on $\mathrm{CO}_{2}$ fluxes calculated by the eddy-covariance method and including the cospectral peak method criteria. At low wind speeds, the transfer velocity in the shallow water estuary was lower than in other coastal waters, possibly a symptom of low tidal amplitude leading to low intensity water turbulence. High transfer velocities were recorded above wind speeds of 5 m $\mathrm{s}^{-1}$ , believed to be caused by early-breaking waves and the large fetch (6.5 km) of the estuary. These findings indicate that turbulence in both air and water influences the transfer velocity.     

Multi-Region Boundary Element Analysis for Coupled Thermal-Fracturing Processes in Geomaterials

This paper describes a boundary element code development on coupled thermal–mechanical processes of rock fracture propagation. The code development was based on the fracture mechanics code FRACOD that has previously been developed by Shen and Stephansson (Int J Eng Fracture Mech 47:177–189, 1993) and FRACOM (A fracture propagation code—FRACOD, User’s manual. FRACOM Ltd. 2002) and simulates complex fracture propagation in rocks governed by both tensile and shear mechanisms. For the coupled thermal-fracturing analysis, an indirect boundary element method, namely the fictitious heat source method, was implemented in FRACOD to simulate the temperature change and thermal stresses in rocks. This indirect method is particularly suitable for the thermal-fracturing coupling in FRACOD where the displacement discontinuity method is used for mechanical simulation. The coupled code was also extended to simulate multiple region problems in which rock mass, concrete linings and insulation layers with different thermal and mechanical properties were present. Both verification and application cases were presented where a point heat source in a 2D infinite medium and a pilot LNG underground cavern were solved and studied using the coupled code. Good agreement was observed between the simulation results, analytical solutions and in situ measurements which validates an applicability of the developed coupled code.     

Strengthened East Asian summer monsoons during a period of high-latitude warmth? Isotopic evidence from Mio-Pliocene fossil mammals and soil carbonates from northern China

The East Asian monsoons have fluctuated in concert with high-latitude warmth during the past several hundred thousand years, with humid summer monsoon-dominant climates characterizing warm intervals, including interglacials and interstadials, and arid winter monsoon-dominant climates characterizing cool intervals, including glacials and stadials. Of the states comprising the mid-Pleistocene to recent climatic regime, interglacials are most similar in terms of high latitude ice volumes and temperatures to those extant during the late Miocene and early Pliocene. Thus, an important question is whether Mio-Pliocene climates in northern China were analogous to a hypothetical ‘prolonged interglacial state,’ with increased summer monsoon precipitation and expansion of forest and steppe environments at the expense of desert environments.We utilize new and previously published carbon isotopic data from fossil teeth and soil carbonates to place constraints on paleovegetation distributions and to help infer the behavior of the monsoon system between ～ 7 and 4 Ma. We find that plants using the C₄ photosynthetic pathway—which today are largely grasses found in regions with warm season precipitation—were present in northern China by late Miocene time, demonstrating that the C₄ expansion in China was not significantly delayed compared to the global C₄ event. During the late Miocene–early Pliocene interval, soil carbonate and tooth enamel δ¹³C data indicate: 1) that nearly pure C₃-plant ecosystems existed in the southern Chinese Loess Plateau (CLP), and therefore ecosystems there were dominated by woody dicot, herbaceous dicot, or cool-season grass vegetation (or a combination of these), and 2) that the CLP was characterized by a pattern of northward-increasing C₄ vegetation and aridity. Utilizing a broadened conceptual model for interpreting δ¹³C data, and citing independent faunal, floral, and lithostratgraphic data, we suggest that these patterns reflect northward expansion of forest and steppe ecosystems and relatively humid monsoon climates during the late Miocene and early Pliocene. An important implication of this interpretation is that the forcing mechanism illuminated by the temporal correlation during the Pleistocene between warm high latitudes and strong East Asian summer monsoons is a robust feature of the Eurasian tectonic–climatic system that predates the Plio-Pleistocene climatic reorganization.     

Process oriented use of geostatistics to analyse creeping para‐glacial features

Complex para‐glacial systems may show signs of destabilization leading to frequent and potentially hazardous debris‐flows. Understanding creeping permafrost displacement over a period of time is therefore crucial for hazard management and risks assessment. This paper presents our methodology for estimating creeping permafrost displacement based upon data derived from various survey methods and demonstrates its relevance on the Glacier Bonnard system in southern Switzerland. Geostatistical processing allowed estimation of the displacement intensity over the area of interest, as well as assessment of the interpolation quality. Although the local measurement network needs to be refined, the results largely improve the understanding of the Bonnard para‐glacial system, though highlighting the need to locally refine the measurement network. In the present case, the destabilized front advances at ~1 m/a and the upstream creeping part at ~0.4 m/a. Variance analysis also provide objective thresholds that could be used to distinguish underlying physical processes. Copyright © 2015 John Wiley & Sons, Ltd.