Weather and seasonal climate prediction for flood planning in the Yangtze River Basin     

Zhaohui Lin  Jason K. Levy  Xingkui Xu  Sixiong Zhao  Jens Hartmann 《Stochastic Environmental Research and Risk Assessment (SERRA)》2005,19(6):428-437

This paper describes the use of numerical weather and climate models for predicting severe rainfall anomalies over the Yangtze River Basin (YRB) from several days to several months in advance. Such predictions are extremely valuable, allowing time for proactive flood protection measures to be taken. Specifically, the dynamical climate prediction system (IAP DCP-II), developed by the Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP), is applied to YRB rainfall prediction and flood planning. IAP DCP-II employs ensemble prediction with dynamically conditioned perturbations to reduce the uncertainty associated with seasonal climate prediction. IAP DCP-II was shown to successfully predict seasonal YRB summer flooding events based on a 15-year (1980–1994) hindcast experiment and the real-time prediction of two summer flooding events (1999 and 2001). Finally, challenges and opportunities for applying seasonal dynamical forecasting to flood management problems in the YRB are discussed.  相似文献   

Cratons and orogenic belts of the Brazilian Shield and their contained gold deposits   总被引：2，自引：0，他引：2  

Leó A. Hartmann  Inácio Delgado 《Mineralium Deposita》2001,36(3-4):207-217

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Discovery of Neoproterozoic juvenile accretion and crustal remobilization belts formed during the Brasiliano Cycle in southern Brazil, based on U-Pb and Sm-Nd geochronology     

M. Babinski  F. Chemale  Jr.  L. A. Hartmann  L. C. Silva  W. R. Van Schmus 《Journal of South American Earth Sciences》1995,8(3-4)

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The manganese nodules of the Kane Gap (East Atlantic). Indicators of sedimentation — erosion changes     

M. Hartmann  M. Segl  A. Mangini  J. Beer  G. Bonani  M. Suter  W. Wölfli 《International Journal of Earth Sciences》1989,78(3):943-958

Manganese nodules from the Kane Gap (a deep sea channel connecting the Sierra Leone and Gambia Basins off West Africa) were investigated chemically and dated by¹⁰Be along cross-sections. Comparing the nodule structure with the stratigraphy of the related sediments, the following conclusions are drawn concerning the sedimentation processes during the last 4 to 6×10⁶ years: The growth of the nodules started about 4 to 4.5 Ma before present during or near to the end of a period of erosion on a fossil-free, probably Miocene sediment. During the first phase of only a few hundred thousandyears, the nodules grew very quickly (7 to >18 mm/Ma). Fe-rich hydrogenetic material formed the internal sections of the nodules during this time. Slowing down of the bottom currents, resulting in deposition of thin sediment covers for short intervals, caused the character of the nodules to change to a more diagenetic composition. The growth rates were reduced to about 1 to 2 mm/Ma. The time of slowing is roughly 3 to 4 Ma BP.Probable uncertainties of the dating and growth rates resulting from supposed changes of the¹⁰Be supply to the nodules due to variations of the near bottom environment are discussed.

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Zusammenfassung An Manganknollen aus der Kane-Lücke, dem Verbindungskanal zwischen Sierra Leone Becken und Gambia Becken (vor W-Afrika) wurden entlang Querprofilen durch mehrere Knollen chemische Untersuchungen und¹⁰Be Altersbestimmungen durchgeführt. Durch Vergleich des Aufbaus der Knollen mit der Stratigraphie des unterlagernden Sediments werden Rückschlüsse auf Veränderungen des Sedimentationsgeschehens während der letzten 4–6×10⁶ Jahre gezogen. Hiernach begann das Wachstum der Knollen vor maximal 4.5×10⁶ Jahren während oder gegen Ende einer Erosionsphase auf fossilfreiem, vermutlich miozänem Sediment. Während der ersten Phase wuchsen die Knollen über wenige 100000 Jahre sehr schnell (7 bis>18 mm/10⁶ Jahre). Hierbei schied sich Fe-reiche Knollensubstanz hydrogener Zusammensetzung ab. Nach Verringerung der Strömung und vermutlich zeitweiser Bildung von dünnen Sedimentschleiern änderte sich der Charakter der Knollen zu mehr diagnetischer Zusammensetzung bei wesentlich reduziertem Wachstum (ca. 1 bis 2 mm/10⁶ Jahre). Der Zeitpunkt der Umstellung ist nur sehr grob zu ermitteln, er dürfte etwa zwischen 3 und 4×10⁶ Jahren vor heute liegen.Eventuelle Unsicherheiten bei der Datierung und den Wachstumsraten, die möglicherweise aus milieubedingten Änderungen in der¹⁰Be Versorgung der Knollen resultieren, werden diskutiert.

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Résumé Le «Kana Gap» est un chenal sous-marin qui relie les bassins de Sierra Leone et de Gambie, au large de l'Afrique occidentale. Des nodules de manganèse, recueillis le long de profils transversaux dans ce chenal, ont fait l'objet d'une étude chimique et d'une détermination d'âge¹⁰Be. La comparaison entre la structure des nodules et la stratigraphie des sédiments sous-jacents permet de tirer les conclusions suivantes relatives au processus sédimentaire au cours des 4 à 6 derniers Ma. La croissance des nodules a commencé il y a environ 4 à 4,5 Ma pendant ou juste après un épisode d'érosion sous-marine sur des sédiments non fossilifères, probablement miocènes. Au cours d'une première phase d'une durée de quelques centaines de milliers d'années, la croissance a été très rapide (7 à > 18 mm par Ma) avec formation de la partie centrale du nodule, constituée de matière hydrogénée riche en Fe. Ensuite, après ralentissement des courants de fond et dépôt probable d'une mince couche de sédiment, le caractère des nodules a évolué vers une composition plus diagénétique, avec réduction du taux de croissance à 1 à 2 mm par Ma. Le moment de ce changement de régime doit se situer entre 3 et 4 Ma.Des changements dans les conditions de milieu sur le fond de la mer pourraient avoir provoqué une variation de la quantité de¹⁰Be apportée aux nodules, d'où résulterait une incertitude sur l'estimation des âges et du taux de croissance; cette question est discutée par les auteurs.

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¹⁰ , , , . , 4х10⁶–6×10⁶ . , 4,5х10⁶ , , , . 100.000 : 7 18 . , . , , : 1 2 . , 3х10⁶–4х 10⁶ . , , , , ¹⁰ .

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Crustal structure of the Lofoten continental margin, off northern Norway, from ocean-bottom seismographic studies   总被引：2，自引：0，他引：2  

S. Kodaira  A. Goldschmidt-Rokita  J. M. Hartmann  H. B. Hirschleber  T. Iwasaki  T. Kanazawa  H. Krahn  S. Tomita  H. Shimamura 《Geophysical Journal International》1995,121(3):907-924

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Satellite-sized planetesimals and lunar origin   总被引：1，自引：0，他引：1  

William K. Hartmann  Donald R. Davis 《Icarus》1975,24(4):504-515

Exploratory calculations using accretionary theory are made to demonstrate plausible sizes of second-largest, third-largest, etc., bodies at the close of planet formation in heliocentric orbits near the planets, assuming asteroid-like size distributions at the start of the calculation. Many satellite-sized bodies are found to be available for capture, cratering, or collisional fragmentation. In the case of Earth-sized planets, the models suggest second-largest bodies of 500 to 3000 km radius, and tens of bodies larger than 100 km radius. Many of these interact with the planet before suffering any fragmentation events with each other. Collision of a large body with Earth could eject iron-deficient crust and upper mantle material, forming a cloud of refractory, volatile-poor dust that could form the Moon. Other satellite systems may have been affected by major capture or collision events of chance character.  相似文献   

Temporal Gravity Variations near Shrinking Vatnajökull Ice Cap, Iceland     

Wolfgang R. Jacoby  Oliver Hartmann  Herbert Wallner  Peter L. Smilde  Stefan Bürger  Lars E. Sjöberg  Sigurdur Erlingsson  Detlef Wolf  Volker Klemann  Ingo Sasgen 《Pure and Applied Geophysics》2009,166(8-9):1283-1302

Repeated gravity measurements were carried out from 1991 until 1999 at sites SE of Vatnajökull, Iceland, to estimate the mass flow and deformation accompanying the shrinking of the ice cap. Published GPS data show an uplift of about 13 ± 5 mm/a near the ice margin. A gravity decrease of –2 ± 1 μGal/a relative to the Höfn base station, was observed for the same sites. Control measurements at the Höfn station showed a gravity decrease of –2 ± 0.5 µGal/a relative to the station RVIK 5473 at Reykjavík (about 250 km from Höfn). This is compatible, as a Bouguer effect, with a 10 ± 3 mm/a uplift rate of the IGS point at Höfn and an uplift rate of ~20 mm/a near the ice margin. Although the derived gravity change rates at individual sites have large uncertainties, the ensemble of the rates varies systematically and significantly with distance from the ice. The relationship between gravity and elevation changes and the shrinking ice mass is modelled as response to the loading history. The GPS data can be explained by 1-D modelling (i.e., an earth model with a 15-km thick elastic lithosphere and a 7·10¹⁷ Pa·s asthenosphere viscosity), but not the gravity data. Based on 2-D modelling, the gravity data favour a low-viscosity plume in the form of a cylinder of 80 km radius and 10¹⁷ to 10¹⁸ Pa·s viscosity below a 6 km-thick elastic lid, embedded in a layered PREM-type earth, although the elevation data are less well explained by this model. Strain-porosity-hydrology effects are likely to enhance the magnitude of the gravity changes, but need verification by drilling. More accurate data may resolve the discrepancies or suggest improved models.  相似文献   

Salt crust development in paddy fields owing to soil evaporation and drainage: Contribution of chloride and deuterium profile analysis     

Olivier Grünberger  Peggy Macaigne  Jean-Luc Michelot  Christian Hartmann  Somsak Sukchan 《Journal of Hydrology》2008,348(1-2):110-123

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Reviewing the Yarkovsky effect: New light on the delivery of stone and iron meteorites from the asteroid belt     

William K. Hartmann  Paolo Farinella  David Vokrouhlický  Stuart J. Weidenschilling  Alessandro Morbidelli  Francesco Marzari  Donald R. Davis  Eileen Ryan 《Meteoritics & planetary science》1999,34(Z4):A161-A167

Abstract— We give a nonmathematical review of recent work regarding the Yarkovsky effect on asteroidal fragments. This effect may play a critical, but underappreciated, role in delivering meteorites to Earth. Two variants of the effect cause drifts in orbital elements, notably semimajor axes. The “classic” or “diurnal” Yarkovsky effect is associated with diurnal rotation at low obliquity. More recently, a “seasonal” effect has also been described, associated with high obliquity. Studies of these Yarkovsky effects are combined with studies of resonance effects to clarify meteorite delivery. If there were no Yarkovsky drift, asteroid fragments could reach a resonance only if produced very near that resonance. However, objects in resonances typically reach Earth-crossing orbits within a few million years, which is inconsistent with stone meteorites' cosmic-ray exposure (CRE) ages (5–50 Ma) and iron meteorites' CRE ages (100–1000 Ma). In the new view, on the other hand, large objects in the asteroid belt are “fixed” in semimajor axis, but bodies up to 100 m in diameter are in a constant state of mixing and flow, especially if the thermal conductivity of their surface layers is low. Thus, small asteroid fragments may reach the resonances after long periods of drift in the main belt. Yarkovsky drift effects, combined with resonance effects, appear to explain many meteorite properties, including: (1) the long CRE ages of iron meteorites (due to extensive drift lifetimes in the belt); (2) iron meteorites' sampling of numerous parent bodies; (3) the shorter CRE ages of most stone meteorites (due to faster drift, coupled with weaker strength and more rapid collisional erosion); and (4) the abundance of falls from discrete impact events near resonances, such as the 8 Ma CRE age of H chondrites. Other consequences include: the delivery of meteorite parent bodies to resonances is enhanced; proportions of stone and iron meteorites delivered to Earth may be different from the proportions at the same sizes left in the belt, which in turn may differ from the ratio produced in asteroidal collisions; Rabinowitz's 10–100 m objects may be preferentially delivered to near-Earth space; and the delivery of C-class fragments from the outer belt may be inhibited, compared to classes in other parts of the belt. Thus, Yarkovsky effects may have important consequences in meteoritics and asteroid science.  相似文献   

Martian cratering 11. Utilizing decameter scale crater populations to study Martian history          下载免费PDF全文

W. K. Hartmann  I. J. Daubar 《Meteoritics & planetary science》2017,52(3):493-510

New information has been obtained in recent years regarding formation rates and the production size‐frequency distribution (PSFD) of decameter‐scale primary Martian craters formed during recent orbiter missions. Here we compare the PSFD of the currently forming small primaries (P) with new data on the PSFD of the total small crater population that includes primaries and field secondaries (P + fS), which represents an average over longer time periods. The two data sets, if used in a combined manner, have extraordinary potential for clarifying not only the evolutionary history and resurfacing episodes of small Martian geological formations (as small as one or few km²) but also possible episodes of recent climatic change. In response to recent discussions of statistical methodologies, we point out that crater counts do not produce idealized statistics, and that inherent uncertainties limit improvements that can be made by more sophisticated statistical analyses. We propose three mutually supportive procedures for interpreting crater counts of small craters in this context. Applications of these procedures support suggestions that topographic features in upper meters of mid‐latitude ice‐rich areas date only from the last few periods of extreme Martian obliquity, and associated predicted climate excursions.  相似文献