Vesta's mineralogical composition as revealed by the visible and infrared spectrometer on Dawn     

M. Cristina De Sanctis  Eleonora Ammannito  M. Teresa Capria  Fabrizio Capaccioni  Jean‐Philippe Combe  Alessandro Frigeri  Andrea Longobardo  Gianfranco Magni  Simone Marchi  Tom B. McCord  Ernesto Palomba  Federico Tosi  Francesca Zambon  Francesco Carraro  Sergio Fonte  Y. J. Li  Lucy A. McFadden  David W. Mittlefehldt  Carle M. Pieters  Ralf Jaumann  Katrin Stephan  Carol A. Raymond  Christopher T. Russell 《Meteoritics & planetary science》2013,48(11):2166-2184

The Dawn spacecraft mission has provided extensive new and detailed data on Vesta that confirm and strengthen the Vesta–howardite–eucrite–diogenite (HED) meteorite link and the concept that Vesta is differentiated, as derived from earlier telescopic observations. Here, we present results derived by newly calibrated spectra of Vesta. The comparison between data from the Dawn imaging spectrometer—VIR—and the different class of HED meteorites shows that average spectrum of Vesta resembles howardite spectra. Nevertheless, the Vesta spectra at high spatial resolution reveal variations in the distribution of HED‐like mineralogies on the asteroid. The data have been used to derive HED distribution on Vesta, reported in Ammannito et al. (2013), and to compute the average Vestan spectra of the different HED lithologies, reported here. The spectra indicate that, not only are all the different HED lithologies present on Vesta, but also carbonaceous chondritic material, which constitutes the most abundant inclusion type found in howardites, is widespread. However, the hydration feature used to identify carbonaceous chondrite material varies significantly on Vesta, revealing different band shapes. The characteristic of these hydration features cannot be explained solely by infalling of carbonaceous chondrite meteorites and other possible origins must be considered. The relative proportion of HEDs on Vesta's surface is computed, and results show that most of the vestan surface is compatible with eucrite‐rich howardites and/or cumulate or polymict eucrites. A very small percentage of surface is covered by diogenite, and basaltic eucrite terrains are relatively few compared with the abundance of basaltic eucrites in the HED suite. The largest abundance of diogenitic material is found in the Rheasilvia region, a deep basin, where it clearly occurs below a basaltic upper crust. However, diogenite is also found elsewhere; although the depth to diogenite is consistent with one magma ocean model, its lateral extent is not well constrained.  相似文献   

Low signal-to-noise event detection based on waveform stacking and cross-correlation: application to a stimulation experiment   总被引：1，自引：1，他引：0  

Katrin Plenkers  Joachim R. R. Ritter  Marion Schindler 《Journal of Seismology》2013,17(1):27-49

We study the microseismicity (M _L ?<?2) in the region of Landau, SW Germany. Here, due to thick sediments (~3?km) and high cultural seismic noise, the signal-to-noise ratio is in general very low for microearthquakes. To gain new insights into the occurrence of very small seismic events, we apply a three-step detection approach and are able to identify 207 microseismic events (?1?<?M _L ?<?~1) with signal-to-noise ratios smaller than 3. Recordings from a temporary broadband network are used with station distances of approximately 10?km. First, we apply a short-term to long-term average detection algorithm for data reduction. The detection algorithm is affected severely by transient noise signals. Therefore, the most promising detections, selected by coinciding triggers and high-amplitude measures, are reviewed manually. Thirteen seismic events are identified in this way. Finally, we conduct a cross-correlation analysis. As master template, we use the stacked waveforms of five manually detected seismic events with a repeating waveform. This search reveals additional 194 events with a cross-correlation coefficient exceeding 0.65 which ensures a stable identification. Our analysis shows that the repeating events occurred during the stimulation of a geothermal reservoir within a source region of only about 0.5?km³. Natural background seismicity exceeding our detection level of M _L ?~?0.7 is not found in the region of Landau by our analysis.  相似文献   

Effects of chronic exposure to dispersed oil on selected reproductive processes in adult blue mussels (Mytilus edulis) and the consequences for the early life stages of their larvae     

Baussant T  Ortiz-Zarragoitia M  Cajaraville MP  Bechmann RK  Taban IC  Sanni S 《Marine pollution bulletin》2011,62(7):1437-1445

Mussels (Mytilus edulis) were continuously exposed to dispersed crude oil (0.015-0.25 mg/l) for 7 months covering the whole gamete development cycle. After 1 month exposure to 0.25 mg oil/l, the level of alkali-labile phosphates (ALP) and the volume density of atretic oocytes in female gonads were higher than those in the gonads of control females, indicating that oil affected the level of vitellogenin-like proteins and gamete development. Spawning of mussels was induced after 7 months oil exposure. Parental oil exposure did not affect subsequent fertilization success in clean seawater but this was reduced in 0.25 mg oil/l. Parental exposure to 0.25 mg oil/l caused both slow development and a higher percentage of abnormalities in D-shell larvae 2 days post-fertilization; reduced growth 7 days post-fertilization. These effects were greatly enhanced when larval stages were maintained at 0.25 mg oil/l. Similar studies are warranted for risk assessment prognosis.  相似文献   

Projections of global warming-induced impacts on winter storm losses in the German private household sector     

Hermann Held  Friedrich-Wilhelm Gerstengarbe  Tobias Pardowitz  Joaquim G. Pinto  Uwe Ulbrich  Kai Born  Markus G. Donat  Melanie K. Karremann  Gregor C. Leckebusch  Patrick Ludwig  Katrin M. Nissen  Hermann Österle  Boris F. Prahl  Peter C. Werner  Daniel J. Befort  Olaf Burghoff 《Climatic change》2013,121(2):195-207

We present projections of winter storm-induced insured losses in the German residential building sector for the 21st century. With this aim, two structurally most independent downscaling methods and one hybrid downscaling method are applied to a 3-member ensemble of ECHAM5/MPI-OM1 A1B scenario simulations. One method uses dynamical downscaling of intense winter storm events in the global model, and a transfer function to relate regional wind speeds to losses. The second method is based on a reshuffling of present day weather situations and sequences taking into account the change of their frequencies according to the linear temperature trends of the global runs. The third method uses statistical-dynamical downscaling, considering frequency changes of the occurrence of storm-prone weather patterns, and translation into loss by using empirical statistical distributions. The A1B scenario ensemble was downscaled by all three methods until 2070, and by the (statistical-) dynamical methods until 2100. Furthermore, all methods assume a constant statistical relationship between meteorology and insured losses and no developments other than climate change, such as in constructions or claims management. The study utilizes data provided by the German Insurance Association encompassing 24 years and with district-scale resolution. Compared to 1971–2000, the downscaling methods indicate an increase of 10-year return values (i.e. loss ratios per return period) of 6–35 % for 2011–2040, of 20–30 % for 2041–2070, and of 40–55 % for 2071–2100, respectively. Convolving various sources of uncertainty in one confidence statement (data-, loss model-, storm realization-, and Pareto fit-uncertainty), the return-level confidence interval for a return period of 15 years expands by more than a factor of two. Finally, we suggest how practitioners can deal with alternative scenarios or possible natural excursions of observed losses.  相似文献   

Challenges of deep-sea biodiversity assessments in the Southern Ocean     

Angelika Brandt  Huw Griffiths  Julian Gutt  Katrin Linse  Stefano Schiaparelli  Tosca Ballerini  Bruno Danis  Olaf Pfannkuche 《极地研究(英文版)》2014,(3):204-212

Despite recent progress in deep-sea biodiversity assessments in the Southern Ocean （SO）, there remain gaps in our knowledge that hamper efficient deep-sea monitoring in times of rapid climate change. These include geographical sampling bias, depth and size-dependent faunal gaps in biology, ecology, distribution, and phylogeography, and the evolution of SO species. The phenomena of species patchiness and rarity are still not well understood, possibly because of our limited understanding of physiological adaptations and thresholds. Even though some shallow water species have been investigated physiologically, community-scale studies on the effects of multiple stressors related to ongoing environmental change, including temperature rise, ocean acidification, and shifts in deposition of phytoplankton, are completely unknown for deep-sea organisms. Thus, the establishment of long-term and coordinated monitoring programs, such as those rapidly growing under the umbrella of the Southern Ocean Observing System （SOOS） or the Deep Ocean Observing Strategy （DOOS）, may represent unique tools for measuring the status and trends of deep-sea and SO ecosystems.  相似文献   

Climatic response of Quaternary alluvial deposits in the upper Kali Gandaki valley (West Nepal)     

Katrin Monecke  Jutta Winsemann  Jrg Hanisch 《Global and Planetary Change》2001,28(1-4)

The terraces at the confluence of Kali Gandaki and Miristi Khola (West Nepal) consist of coarse-grained deposits which are considered to be Late Pleistocene to Holocene in age. The stacking pattern of lithofacies is characterised by an alternation of fluvial and debris flow deposits. These periodic changes in sedimentation processes are attributed to climatic variations.Deposits of extended, highly mobile, braided rivers most probably developed under glacial conditions and reflect high sediment supply and high water discharge rates. Deposits of small, only moderately braided river systems evolved during a warmer climate with comparatively low sediment supply and water discharge rates. The mobilisation and redeposition of morainic material by enormous debris flows predominately occurred at the beginning of a warm period and was triggered by earthquakes, glacier lake outburst floods or strong monsoonal rain.  相似文献   

Exploring public perceptions of stratospheric sulfate injection     

Christine Merk  Gert Pönitzsch  Carola Kniebes  Katrin Rehdanz  Ulrich Schmidt 《Climatic change》2015,130(2):299-312

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Exploring biological constraints on the glacial history of Antarctica     

Peter Convey  Mark I. Stevens  Dominic A. Hodgson  John L. Smellie  Claus-Dieter Hillenbrand  David K.A. Barnes  Andrew Clarke  Philip J.A. Pugh  Katrin Linse  S. Craig Cary 《Quaternary Science Reviews》2009,28(27-28):3035-3048

The evolutionary and biogeographic history of the contemporary Antarctic terrestrial and marine biotas reveals many components of ancient origin. For large elements of the terrestrial biota, long-term isolation over timescales from hundreds of thousands to tens of millions of years, and thus persistence through multiple glacial cycles, now appears to be the norm rather than the exception. For the marine biota there are some parallels with benthic communities also including ancient components, together with an incidence of species-level endemism indicating long-term isolation on the Antarctic continental shelf. Although it has long been known that a few ice-free terrestrial locations have existed in Antarctica for up to 10–12 million years, particularly in the Dry Valleys of Victoria Land along with certain nunataks and higher regions of large mountain ranges, these do not provide potential refugia for the majority of terrestrial biota, which occur mainly in coastal and/or low-lying locations and exhibit considerable biogeographic regionalisation within the continent. Current glacial models and reconstructions do not have the spatial resolution to detect unequivocally either the number or geographical distribution of these glacial refugia, or areas of the continental shelf that have remained periodically free from ice scouring, but do provide limits for their maximum spatial extent. Recent work on the evolution of the terrestrial biota indicates that refugia were much more widespread than has been recognised and it is now clear that terrestrial biology provides novel constraints for reconstructing the past glacial history of Antarctica, and new marine biological investigations of the Antarctic shelf are starting to do likewise.  相似文献   

Chronology of Late Weichselian glaciation in the western part of the East European Plain     

Katrin Lasberg  Volli Kalm 《Boreas: An International Journal of Quaternary Research》2013,42(4):995-1007

A database consisting of radiocarbon (¹⁴C), optically stimulated luminescence (OSL), thermoluminescence (TL) and beryllium (¹⁰Be) dates was used for timing the advance of the Late Weichselian Scandinavian Ice Sheet (SIS), determining the age of the Last Glacial Maximum (LGM) and the rate of deglaciation. The study area encompasses the southeastern sector of the last SIS between the Baltic Sea and the LGM position in the western part of the East European Plain, covering the Karelian Ice‐Stream Complex (ISC) area in the east and the Baltic ISC area in the west. The linear advance and recession rates of the last SIS were estimated to be between 110 and 330 m a^?1 and between 50 and 170 m a^?1, respectively. The onset of the last SIS in the Karelian ISC area reached the western shores of Latvia not before 26 OSL ka, and in the Baltic ISC area, on the southern shores of the Gulf of Finland, not before 21 OSL ka. The last SIS reached close to the LGM position earliest in NW Belarus, not earlier than 22.6 cal. ¹⁴C ka BP, and latest in the NE of Belarus, not earlier than 19.1 cal. ¹⁴C ka BP. The Baltic ISC area between the LGM position and the western shores of Latvia was deglaciated in about 8 ka, and in the Karelian ISC area, between the LGM position and the southern shores of the Gulf of Finland, in about 2.6 ka. The whole area between the LGM position and the Baltic Sea was deglaciated between 14.2 ¹⁰Be ka and 13.3 cal. ¹⁴C ka BP.  相似文献   

Hedonic Pricing of Climate Change Impacts to Households in Great Britain     

Katrin Rehdanz 《Climatic change》2006,74(4):413-434

This study investigates the amenity value of climate to British households. By using the hedonic price approach, the marginal willingness to pay for small changes in climate variables is derived. Various indices of temperature and precipitation are used including means, ranges, extremes and January and July averages. We specify one hedonic regression including information on house prices and wage data for 755 Posttowns and found the model containing January and July averages of temperature and precipitation most appropriate. The estimates suggest that British people would typically prefer higher temperatures in January. Increased precipitation in January is likely to reduce welfare. Changes in temperature and precipitation in July are not significant. Limited global warming, with a more pronounced effect of temperature increases compared to higher precipitation levels during winter months, might thus benefit British households.  相似文献