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191.
192.
Climate Dynamics - Recent work has identified potential multi-year predictability in soil moisture (Chikamoto et al. in Clim Dyn 45(7–8):2213–2235, 2015). Whether this long-term... 相似文献
193.
David Mimoun Mark A. Wieczorek Leon Alkalai W. Bruce Banerdt David Baratoux Jean-Louis Bougeret Sylvain Bouley Baptiste Cecconi Heino Falcke Joachim Flohrer Raphael F. Garcia Robert Grimm Matthias Grott Leonid Gurvits Ralf Jaumann Catherine L. Johnson Martin Knapmeyer Naoki Kobayashi Alexander Konovalenko David Lawrence Mathieu Le Feuvre Philippe Lognonné Clive Neal Jürgen Oberst Nils Olsen Huub R?ttgering Tilman Spohn Susanne Vennerstrom Graham Woan Philippe Zarka 《Experimental Astronomy》2012,33(2-3):529-585
Farside Explorer is a proposed Cosmic Vision medium-size mission to the farside of the Moon consisting of two landers and an instrumented relay satellite. The farside of the Moon is a unique scientific platform in that it is shielded from terrestrial radio-frequency interference, it recorded the primary differentiation and evolution of the Moon, it can be continuously monitored from the Earth–Moon L2 Lagrange point, and there is a complete lack of reflected solar illumination from the Earth. Farside Explorer will exploit these properties and make the first radio-astronomy measurements from the most radio-quiet region of near-Earth space, determine the internal structure and thermal evolution of the Moon, from crust to core, and quantify impact hazards in near-Earth space by the measurement of flashes generated by impact events. The Farside Explorer flight system includes two identical solar-powered landers and a science/telecommunications relay satellite to be placed in a halo orbit about the Earth–Moon L2 Lagrange point. One lander would explore the largest and oldest recognized impact basin in the Solar System— the South Pole–Aitken basin—and the other would investigate the primordial highlands crust. Radio astronomy, geophysical, and geochemical instruments would be deployed on the surface, and the relay satellite would continuously monitor the surface for impact events. 相似文献
194.
We combine a convectively driven dynamo in a spherical shell with a nearly isothermal density-stratified cooling layer that mimics some aspects of a stellar corona to study the emergence and ejections of magnetic field structures. This approach is an extension of earlier models, where forced turbulence simulations were employed to generate magnetic fields. A spherical wedge is used which consists of a convection zone and an extended coronal region to ???1.5 times the radius of the sphere. The wedge contains a quarter of the azimuthal extent of the sphere and 150° in latitude. The magnetic field is self-consistently generated by the turbulent motions due to convection beneath the surface. Magnetic fields are found to emerge at the surface and are ejected to the coronal part of the domain. These ejections occur at irregular intervals and are weaker than in earlier work. We tentatively associate these events with coronal mass ejections on the Sun, even though our model of the solar atmosphere is rather simplistic. 相似文献
195.
Nadine Friese Axel Vollbrecht David C. Tanner Wiebke Fahlbusch Miriam Weidemann 《International Journal of Earth Sciences》2012,101(5):1149-1167
The emplacement of the Mesoproterozoic G?temar Pluton into Paleoproterozoic granitoid host rocks of the Transscandinavian Igneous Belt is re-examined by microfabric analysis, including cathodoluminescence microscopy. Field data on the pluton-host rock system are used to strengthen the model. The G?temar Pluton, situated on the Baltic Shield of SE Sweden, is a horizontally zoned tabular structure that was constructed by the intrusion of successive pulses of magma with different crystal/melt ratios, at an estimated crustal depth of 4–8?km. Initial pluton formation involved magma ascent along a vertical dike, which was arrested at a mechanical discontinuity within the granitoid host rocks; this led to the formation of an initial sill. Subsequent sill stacking and their constant inflation resulted in deformation and reheating of existing magma bodies, which also raised the pluton roof. This multi-stage emplacement scenario is indicated by complex dike relationships and the occurrence of several generations of quartz (Si-metasomatism). The sills were charged by different domains of a heterogeneous magma chamber with varying crystal/melt ratios. Ascent or emplacement of magma with a high crystal/melt ratio is indicated by syn-magmatic deformation of phenocrysts. Complex crystallization fabrics (e.g. oscillatory growth zoning caused by high crystal defect density, overgrowth and replacement features, resorbed and corroded crystal cores, rapakivi structure) are mostly related to processes within the main chamber, that is repeated magma mixing or water influx. 相似文献
196.
Decoupled crystallization and eruption histories of the rhyolite magmatic system at Tarawera volcano revealed by zircon ages and growth rates 总被引:2,自引:2,他引:0
Sonja?StormEmail author Phil?Shane Axel?K.?Schmitt Jan?M.?Lindsay 《Contributions to Mineralogy and Petrology》2012,163(3):505-519
We obtained U–Th disequilibrium age data on zircons from each of the four rhyolite eruptions that built Tarawera volcano in
the last 22 ka within the Okataina Volcanic Center (OVC), caldera, New Zealand. Secondary ion mass spectrometry analyses on
unpolished euhedral crystal faces that lack resorption features show that crystal growth variously terminated from near-eruption
age to ~100 ka prior to eruption. Age-depth profiling of crystals reveals long periods of continuous (~34 ka) and discontinuous
growth (~90 ka). Growth hiatuses of up to ~40 ka duration occur, but do not all relate to obvious resorption surfaces. Age
differences up to similar magnitude are found on opposing faces of some crystals suggesting episodes of partial exposure to
melts. These features are best explained by periodic, complete, or partial, sub-solidus storage and/or inclusion in larger
crystal phases, followed by rapid liberation prior to eruption. This is supported by high abundances of U and Th (~500 − >2,000 ppm)
in some zircons consistent with periods of high crystallinity (>70%) in the magmatic system, based on crystal/melt partitioning.
Contemporaneous but contrasting rim-ward trends of these elements within crystals, even in the same lava hand sample, require
synchronous growth in separate melt bodies and little connectivity within the system, but also significant crystal transport
and mixing prior to eruption. Many crystals record continuity of growth through the preceding ~60 ka OVC caldera-collapse
and subsequent eruptions from Tarawera. This demonstrates a decoupling between eruption triggers, such as shallow crustal
extension and mafic intrusion, and the crystallization state of the OVC silicic magmatic system. The data highlights the need
to distinguish between the time for accumulation of eruptible magma and the long-term magma residence time based on the age
of crystals with high closure temperatures, when assessing the potential for catastrophic eruptions. 相似文献
197.
198.
We examine the effect of random horizontal flows on the dispersion relation of high-degree solar f modes. We follow the approach of Murawski and Roberts (Astron. Astrophys. 272, 595, 1993), addressing some limitations of that paper, and extending the results to include damping and to apply for a general turbulent spectrum. We find a reduction in frequency below the classical result that is about three times that observed. For large wavenumber the damping rate is larger than the frequency correction by a factor of the order of the nondimensional wavenumber, which appears to be consistent with observation. 相似文献
199.
Soon-Il An Jae-Heung Park Baek-Min Kim Axel Timmermann Fei-Fei Jin 《Theoretical and Applied Climatology》2012,107(1-2):155-164
Using a simple tropical climate model, we investigated possible impacts of changes in oceanic seaways (Panama and Tethys) and ocean basin sizes (great Pacific and narrow Atlantic) on tropical climate variability during Tertiary. Our model showed that the opening of seaways had little influence on climate variability in the tropical Pacific because the climate variability in the Pacific Ocean’s large basins were internally generated, regardless of the variation in the tropical Atlantic Ocean. Conversely, the climate variability in the tropical Atlantic Ocean was highly dependent on the tropical Pacific Ocean; thus, an opening seaway, particularly the Panama seaway, was crucial in generating the interannual variability in the tropical Atlantic Ocean. We also found that in the Pacific Ocean, basin size strongly modified the period and amplitude of the interannual variability of both the Pacific and Atlantic Oceans due to ocean wave dynamics. 相似文献
200.
Simulating the diurnal cycle of rainfall in global climate models: resolution versus parameterization 总被引:1,自引:1,他引:0
Paul A. Dirmeyer Benjamin A. Cash James L. Kinter III Thomas Jung Lawrence Marx Masaki Satoh Cristiana Stan Hirofumi Tomita Peter Towers Nils Wedi Deepthi Achuthavarier Jennifer M. Adams Eric L. Altshuler Bohua Huang Emilia K. Jin Julia Manganello 《Climate Dynamics》2012,39(1-2):399-418
The effects of horizontal resolution and the treatment of convection on simulation of the diurnal cycle of precipitation during boreal summer are analyzed in several innovative weather and climate model integrations. The simulations include: season-long integrations of the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) with explicit clouds and convection; year-long integrations of the operational Integrated Forecast System (IFS) from the European Centre for Medium-range Weather Forecasts at three resolutions (125, 39 and 16 km); seasonal simulations of the same model at 10 km resolution; and seasonal simulations of the National Center for Atmospheric Research (NCAR) low-resolution climate model with and without an embedded two-dimensional cloud-resolving model in each grid box. NICAM with explicit convection simulates best the phase of the diurnal cycle, as well as many regional features such as rainfall triggered by advancing sea breezes or high topography. However, NICAM greatly overestimates mean rainfall and the magnitude of the diurnal cycle. Introduction of an embedded cloud model within the NCAR model significantly improves global statistics of the seasonal mean and diurnal cycle of rainfall, as well as many regional features. However, errors often remain larger than for the other higher-resolution models. Increasing resolution alone has little impact on the timing of daily rainfall in IFS with parameterized convection, yet the amplitude of the diurnal cycle does improve along with the representation of mean rainfall. Variations during the day in atmospheric prognostic fields appear quite similar among models, suggesting that the distinctive treatments of model physics account for the differences in representing the diurnal cycle of precipitation. 相似文献