The CLIVAR C20C project: skill of simulating Indian monsoon rainfall on interannual to decadal timescales. Does GHG forcing play a role?     

F. Kucharski  A. A. Scaife  J. H. Yoo  C. K. Folland  J. Kinter  J. Knight  D. Fereday  A. M. Fischer  E. K. Jin  J. Kröger  N.-C. Lau  T. Nakaegawa  M. J. Nath  P. Pegion  E. Rozanov  S. Schubert  P. V. Sporyshev  J. Syktus  A. Voldoire  J. H. Yoon  N. Zeng  T. Zhou 《Climate Dynamics》2009,33(5):615-627

The ability of atmospheric general circulation models (AGCMs), that are forced with observed sea surface temperatures (SSTs), to simulate the Indian monsoon rainfall (IMR) variability on interannual to decadal timescales is analyzed in a multimodel intercomparison. The multimodel ensemble has been performed within the CLIVAR International “Climate of the 20th Century” (C20C) Project. This paper is part of a C20C intercomparison of key climate time series. Whereas on the interannual timescale there is modest skill in reproducing the observed IMR variability, on decadal timescale the skill is much larger. It is shown that the decadal IMR variability is largely forced, most likely by tropical sea surface temperatures (SSTs), but as well by extratropical and especially Atlantic Multidecadal Oscillation (AMO) related SSTs. In particular there has been a decrease from the late 1950s to the 1990s that corresponds to a general warming of tropical SSTs. Using a selection of control integrations from the World Climate Research Programme’s (WCRP’s) Coupled Model Intercomparison Project phase 3 (CMIP3), it is shown that the increase of greenhouse gases (GHG) in the twentieth century has not significantly contributed to the observed decadal IMR variability.  相似文献   

Squeezing information from regional climate change projections - results from a synthesis of CMIP5 results for south-east Queensland, Australia     

Ian Smith  Jozef Syktus  Clive McAlpine  Kenneth Wong 《Climatic change》2013,121(4):609-619

We present a synthesis of CMIP5 model results for projected rainfall changes for a single region (south-east Queensland, Australia) and note that, as was evident in CMIP3 results, the multi-model mean projected changes for the late 21st century are not statistically significant for any season nor annually. Taking account of the number of statistically significant changes to mean rainfall, we find some evidence favouring a decrease in both spring and annual rainfall, but this is not compelling. In almost all cases the most frequent result is for no significant change. However, if we consider the number of results where there is a statistically significant change in the distributions of rainfall amounts, there appears to be slightly more information available for risk assessment studies. These numbers suggest an increase in the frequency of both wet and dry events during summer and spring, and a shift towards more frequent dry events during winter. There is no evidence for any significant changes to the distributions for either autumn or annually. The findings suggest that, in one respect, multi-model rainfall projections may contain more information than is evident from syntheses which focus on changes to the means and that, for some regions where changes in the frequency of wet and dry seasons/years have known impacts, the model projections may be more valuable than previously thought.  相似文献   

The Košice meteorite fall: Recovery and strewn field          下载免费PDF全文

Juraj Tóth  Ján Svoreň  Jiří Borovička  Pavel Spurný  Antal Igaz  Leonard Kornoš  Peter Vereš  Marek Husárik  Július Koza  Aleš Kučera  Pavel Zigo  Štefan Gajdoš  Jozef Világi  David Čapek  Zuzana Krišandová  Dušan Tomko  Jiří Šilha  Eva Schunová  Marcela Bodnárová  Diana Búzová  Tereza Krejčová 《Meteoritics & planetary science》2015,50(5):853-863

We provide the circumstances and details of the fireball observation, search expeditions, recovery, strewn field, and physical characteristics of the Ko?ice meteorite that fell in Slovakia on February 28, 2010. The meteorite was only the 15th case of an observed bolide with a recovered mass and subsequent orbit determination. Despite multiple eyewitness reports of the bolide, only three videos from security cameras in Hungary were used for the strewn field determination and orbit computation. Multiple expeditions of professionals and individual searchers found 218 fragments with total weight of 11.3 kg. The strewn field with the size of 5 × 3 km is characterized with respect to the space distribution of the fragments, their mass and size‐frequency distribution. This work describes a catalog of 78 fragments, mass, size, volume, fusion crust, names of discoverers, geographic location, and time of discovery, which represents the most complex study of a fresh meteorite fall. From the analytical results, we classified the Ko?ice meteorite as an ordinary H5 chondrite.  相似文献   

Cosmogenic nuclides in the Košice meteorite: Experimental investigations and Monte Carlo simulations          下载免费PDF全文

Pavel P. Povinec  Jozef Masarik  Ivan Sýkora  Andrej Kováčik  Juraj Beňo  Matthias M. M. Meier  Rainer Wieler  Matthias Laubenstein  Vladimir Porubčan 《Meteoritics & planetary science》2015,50(5):880-892

Results of nondestructive gamma‐ray analyses of cosmogenic radionuclides (⁷Be, ²²Na, ²⁶Al, ⁴⁶Sc, ⁴⁸V, ⁵⁴Mn, ⁵⁶Co, ⁵⁷Co, ⁵⁸Co, and ⁶⁰Co) in 19 fragments of the Ko?ice meteorite are presented and discussed. The activities varied mainly with position of fragments in the meteoroid body, and with fluxes of cosmic‐ray particles in the space affecting radionuclides with different half‐lives. Monte Carlo simulations of the production rates of ⁶⁰Co and ²⁶Al compared with experimental data indicate that the pre‐atmospheric radius of the meteoroid was 50 ± 5 cm. In two Ko?ice fragments, He, Ne, and Ar concentrations and isotopic compositions were also analyzed. The noble‐gas cosmic‐ray exposure age of the Ko?ice meteorite is 5–7 Myr, consistent with the conspicuous peak (or doublet peak) in the exposure age histogram of H chondrites. One sample likely contains traces of implanted solar wind Ne, suggesting that Ko?ice is a regolith breccia. The agreement between the simulated and observed ²⁶Al activities indicate that the meteoroid was mostly irradiated by a long‐term average flux of galactic cosmic rays of 4.8 particles cm^?2 s^?1, whereas the short‐lived radionuclide activities are more consistent with a flux of 7.0 protons cm^?2 s^?1 as a result of the low solar modulation of the galactic cosmic rays during the last few years before the meteorite fall.  相似文献   

Runoff curve numbers for steep hillslopes with natural vegetation in semi‐arid tropical highlands,northern Ethiopia     

Katrien Descheemaeker  Jean Poesen  Lorenzo Borselli  Jan Nyssen  Dirk Raes  Mitiku Haile  Bart Muys  Jozef Deckers 《水文研究》2008,22(20):4097-4105

Daily runoff from 27 plots (5 m × 2 m) recorded during two rainy seasons in the Tigray highlands (Ethiopia) were analysed together with daily rainfall to calculate runoff curve numbers for hillslopes covered by semi‐natural vegetation in varying stages of vegetation restoration. Curve number model parameters were derived using a least squares fitting procedure on the collected rainfall–runoff datasets. Curve numbers varied from 29 to 97. Land use type was an important explanatory factor for the variation in curve numbers, whereas hydrologic soil group was not. Curve numbers were negatively correlated with vegetation cover. Taking into account antecedent soil moisture conditions did not improve runoff prediction using the curve number method. As runoff prediction was less accurate in areas with low curve numbers, two separate regression functions relating curve numbers with vegetation cover were proposed for different land use types. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Rotational overthrusting of the northwestern Himalaya: further palaeomagnetic evidence from the Riasi thrust sheet, Jammu foothills, India     

Chris T. Klootwijk  Madan Lal Sharma  Jozef Gergan  S.K. Shah  B.K. Gupta 《Earth and Planetary Science Letters》1986,80(3-4):375-393

Thermal demagnetization results (316 samples) are presented for the Tertiary succession of the Riasi thrust sheet (Jammu foothills, northwestern Himalaya). Primary and secondary magnetization directions of Murree Group red beds (Miocene to Upper Eocene) sampled northeast of Jammu indicate, for this part of the Riasi thrust sheet, a clockwise rotation over about 45° with respect to the Indian shield since Late Eocene/Early Miocene time. This accords with clockwise rotations of similar magnitude observed in the Panjal Nappe and the Krol Belt, and is interpreted as representative for the northwestern Himalaya. Results from the western part of the Kalakot inlier, sampled northwest of Jammu, i.e. basal Murree claystone (Middle Eocene) and carbonate from the Subathu Group (lower Middle to Lower Eocene), indicate an aberrant 20–25° counterclockwise rotation which is of local importance only. Available observations on rotation of Himalayan thrust sheets with respect to the Indian shield, indicate that the Himalayan Arc has formed through oroclinal bending. This supports Powell and Conaghan's and Veevers et al.'s model of Greater India with large-scale intracontinental underthrusting along the Main Central Thrust beneath the Tibetan Plateau. Minimal magnitudes of underthrusting of 550 km in the Krol Belt and 650 km in the Thakkhola region are concluded. Palaeolatitude observations (herein and in [1[) agree with absolute positioning of the Indian plate based on India-Africa relative movement data fixed to a hotspot frame in the Atlantic Ocean, and with palaeolatitude observations from DSDP cores on the Indian plate. Collision-related secondary magnetic components observed both to the north and to the south of the Indus-Tsangpo Suture zone show palaeolatitudes between the equator and 7°N. Comparison of both datasets indicates that initial contact between Greater India and south-central Asia had been established in the Hindu Kush—Karakorum region by about 60 Ma ago whereas eastwards progressive suturing had advanced to the Lhasa Block segment of the Indus-Tsangpo Suture zone before 50 Ma ago.  相似文献   

Composition of waters and sediments in the Antwerp harbor     

Jozef R. Senten  Roger H. Charlier 《Environmental Geology》1983,5(3):159-165

Industrial expansion in the harbor areas of Antwerp has altered environmental conditions to a great extent. This study examines the relation between the water economy of the port of Antwerp docks and the composition of dock waters, sediments, and interstitial waters, with emphasis on trace metals and chlorides. Some conclusions are reached as to the possible use of the dredged deposits in agriculture.  相似文献   

Latitudinal dependence of signal-to-noise patterns from two general circulation models with CO2 forcing     

J. Syktus  J. Chappell  R. Oglesby  J. Larson  S. Marshall  B. Saltzman 《Climate Dynamics》1997,13(5):293-302

 Detection of an enhanced greenhouse effect on climate depends on recognition of a signal of change amidst the combined noise of climatic variability and uncertainty in the nature of the signal (functional response to changing CO₂). Using two different GCMs (one with a coupled dynamic upper ocean) and an ensemble of 20 equilibrium experiments with CO₂ ranging from 100 to 3500 ppm, we find that that two measures of signal-to-noise (S/N) for the response of surface temperature to CO₂ forcing are larger over tropical and subtropical oceans than over low-latitude landmasses and larger than at higher latitudes generally. One S/N measure has the noise based solely on inherent model variability, while the other S/N measure includes both this variability and a measure of the uncertainty in the functional nature of the signal. Although the experiments were not for transient forcing and sulphate aerosols and other potentially important forcings (e.g., ozone or solar variability) were not considered, the results suggest that the effects of enhanced greenhouse climate may be detected more readily in surface temperatures from low-latitude oceanic regions than from global or zonal temperature averages. Received: 27 June 1995/Accepted: 28 October 1996  相似文献   

Immiscible separation of metalliferous Fe/ Ti-oxide melts from fractionating alkali basalt: P-T-f O2 conditions and two-liquid elemental partitioning     

Vratislav Hurai  Klaus Simon  Uwe Wiechert  Jochen Hoefs  Patrik Konečný  Monika Huraiová  Jacques Pironon  Jozef Lipka 《Contributions to Mineralogy and Petrology》1998,133(1-2):12-29

Globules of iron-dominated (59–69 wt% FeO_tot) and titanium-dominated (43.5 wt% TiO₂) oxide melts have been detected in igneous xenoliths from Pliocene-to-Pleistocene alkali basalts of the Western Carpathians. Fluid inclusion and mineral composition data indicate immiscible separation of the high-iron-oxide melt (HIM) at magmatic temperatures. The HIM separation occurred during clinopyroxene (augite) accumulation in an alkali trachybasalt and continued during crystallization of amphibole (kaersutite) and K-feldspar (anorthoclase), the latter coexisting with trachyte and alkalic rhyolite residual melts. Some HIM was also expelled from sub-alkalic rhyolite (70–77% SiO₂), coexisting with An_27–45 plagioclase and quartz in granitic (tonalite-trondhjemite) xenoliths. Oxygen fugacities during HIM separation range from −1.4 to +0.6 log units around the QFM buffer. A close genetic relationship between HIM-hosted xenoliths and mantle-derived basaltic magma is documented by mineral ¹⁸O values ranging from 4.9 to 5.9‰ V-SMOW. δD values of gabbroic kaersutite between −61 and −86‰ V-SMOW are in agreement with a presumed primary magmatic water source. Most trace elements, except Li, Rb and Cs, have preferentially partitioned into the HIM. The HIM/Si-melt partition coefficients for transition elements (Sc, V, Cr, Co, Ni) and base metals (Zn, Cu, Mo) are between 2–160, resulting in extreme enrichment in the HIM. La and Ce also concentrate in the silicic melt, whereas Tb-Tm in the HIM. Hence, the immiscible separation causes REE fractionation and produces residual silicic melt enriched in LREE and depleted in HREE. The weak fractionation among Tb-Tm and Yb, Lu can be attributed to recurrent extraction of the HIM from the magmatic system, while flat HREE chondrite-normalized patterns are interpreted to indicate no or little loss of the HIM. Received: 30 September 1997 / Accepted: 23 March 1998  相似文献   

Fingerprinting of soil organic matter as a proxy for assessing climate and vegetation changes in last interglacial palaeosols (Veldwezelt, Belgium)     

Karen Vancampenhout  Katinka Wouters  Peter Buurman  Jozef Deckers 《Quaternary Research》2008,69(1):145-162

Soil characteristics in palaeosols are an important source of information on past climate and vegetation. Fingerprinting of soil organic matter (SOM) by pyrolysis-GC/MS is assessed as a proxy for palaeo-reconstruction in the complex of humic layers on top of the Rocourt pedosequence in the Veldwezelt-Hezerwater outcrop (Belgian loess belt). The fingerprints of the extractable SOM of different soil units are related to total organic carbon content, δ¹³C and grain-size analysis. Combined results indicate that the lower unit of the humic complex reflects a stable soil surface, allowing SOM build-up, intensive microbial activity and high decomposition. Higher in the profile, decomposition and microbial activity decrease. This is supported by a shift in the isotopic signal, an increased U ratio and evidence of wildfires. Although the chemical composition of the extracted SOM differed greatly from recent SOM, fingerprinting yielded detailed new information on SOM degree of decomposition and microbial contribution, allowing the reconstruction of palaeo-environmental conditions during pedogenesis.  相似文献