Dissimilarity among Ocean Reanalyses in Equatorial Pacific Upper-Ocean Heat Content and Its Relationship with ENSO     

Paxson K.Y.CHEUNG  Wen ZHOU  Dongxiao WANG  Marco Y.T.LEUNG 《大气科学进展》2022,39(1):67-79

This study focuses on the temporal variation of dissimilarity in heat content(HC)anomalies in the upper 300 m of ocean(HC300A)in the equatorial Pacific(±10°N)and its response to the El Ni?o-Southern Oscillation(ENSO).The HC300A anomalies are derived from four ocean reanalyses that are commonly used in ENSO studies and are compared using a simple differencing method.The dissimilarity in HC300A is found to vary closely with the magnitude of ENSO(regardless of phase),meaning that it tends to be greater during strong ENSO events.However,the dissimilarity among ocean reanalyses persists after the event decays.This effect is more pronounced after strong events.The persistence of the dissimilarity after ENSO events is a result of a late maturation of the ENSO signal,its persistence,and the interruption of the signal decay due to follow-up ENSO events.The combined effect of these three factors slows down the decay of HC300A in the region and hence results in the slow decay of dissimilarity.It is also found that areas with a significant spread in vertical temperature profiles collocate with the ENSO signal during warm ENSO phases.Thus,differences in subsurface process reconstruction are a significant factor in the dissimilarity among ocean reanalyses during warm ENSO events.  相似文献   

Hillslope scale soil moisture variability in a steep alpine terrain   总被引：1，自引：0，他引：1  

Daniele Penna  Marco Borga  Daniele Norbiato  Giancarlo Dalla Fontana 《Journal of Hydrology》2009,364(3-4):311-327

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Linkages and feedbacks in highly dynamic alpine fluvial systems     

Angela Gurnell  Marco Tubino  Klement Tockner 《Aquatic Sciences - Research Across Boundaries》2009,71(3):251-252

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Multi-method global sensitivity analysis of flood inundation models   总被引：1，自引：0，他引：1  

Florian Pappenberger  Keith J. Beven  Marco Ratto  Patrick Matgen 《Advances in water resources》2008

Global sensitivity analysis is a valuable tool in understanding flood inundation models and deriving decisions on strategies to reduce model uncertainty. In this paper, a sensitivity analysis of a one-dimensional flood inundation model (HEC-RAS) on the River Alzette, Luxembourg, is presented. It is impossible to define sensitivity in a unique way and different methods can lead to a difference in ranking of importance of model factors. In this paper five different methods (Sobol, Kullback–Leibler entropy, Morris, regionalised sensitivity analysis and regression) are applied and the outcomes on selected examples compared. It is demonstrated that the different methods lead to completely different ranking of importance of the parameter factors and that it is impossible to draw firm conclusions about the relative sensitivity of different factors. Moreover, the uncertainty inherent in the sensitivity methods is highlighted.  相似文献   

Reply to comment by W.U. Reimold, R.L. Gibson, and H. Henkel on Muundjua et al. (2007), “Magnetic imaging of the Vredefort impact crater, South Africa”, EPSL 261, pp 456–468     

Manfriedt Muundjua  Armand Galdeano  Laurent Carporzen  Stuart A. Gilder  Rodger J. Hart  Marco A.G. Andreoli  Marian Tredoux 《Earth and Planetary Science Letters》2008,273(3-4):397-399

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Vibrios in association with sedimentary crustaceans in three beaches of the northern Adriatic Sea (Italy)   总被引：3，自引：0，他引：3  

Covazzi Harriague A  Brino MD  Zampini M  Albertelli G  Pruzzo C  Misic C 《Marine pollution bulletin》2008,56(3):574-579

In the marine environment, vibrios adhere to a number of substrates including chitin-rich organisms such as crustaceans. Their wide diffusion in coastal waters and pathogenic potential require knowledge of the lifestyle and environmental reservoirs of these bacteria. To test the presence of culturable vibrios in coastal areas and their association with benthic crustaceans, vibrios were isolated from water, sediments and crustaceans (copepods and anphipods) at three stations placed in front of heavily used tourist beaches of the Adriatic Sea. We observed significant correlations between vibrios and temperature. Benthic and planktonic copepods harboured vibrios in summer, while benthic amphipods harboured these bacteria in spring and autumn. Vibrio alginolyticus and Vibrio parahaemolyticus strains gave positive results using primers for Vibrio cholerae toxR and toxS. Sedimentary crustaceans may extend Vibrio persistence in seawater and may represent an additional aquatic reservoir of these bacteria.  相似文献   

Body-wave Attenuation in the Region of Garda, Italy   总被引：1，自引：0，他引：1  

Raúl R. Castro  Marco Massa  Paolo Augliera  Francesca Pacor 《Pure and Applied Geophysics》2008,165(7):1351-1366

We analyzed the spectral amplitude decay with hypocentral distance of P and S waves generated by 76 small magnitude earthquakes (M_L 0.9–3.8) located in the Garda region, Central-Eastern Alps, Italy. These events were recorded by 18 stations with velocity sensors, in a distance range between 8 and 120 km. We calculated nonparametric attenuation functions (NAF) and estimated the quality factor Q of both body waves at 17 different frequencies between 2 and 25 Hz. Assuming a homogeneous model we found that the Q frequency dependence of P and S can be approximated with the functions Q _P = 65 f ^0.9 and Q _S = 160 f ^0.6 , respectively. At 2 Hz the Q _S /Q _P ratio reaches the highest value of 2.8. At higher frequencies Q _S /Q _P varies between 0.7 and 1.7, suggesting that for this frequency band scattering may be an important attenuation mechanism in the region of Garda. To explore the variation of Q in depth, we estimated Q at short (r ≤ 30 km) and intermediate (35–90 km) distance paths. We found that in the shallow crust P waves attenuate more than S (1.3 < Q _S /Q _P < 2.5). Moreover, P waves traveling along paths in the lower crust (depths approximately greater than 30 km) attenuate more than S waves. To quantify the observed variability of Q in depth we considered a three-layer model and inverted the NAF to estimate Q in each layer. We found that in the crust Q increases with depth. However, in the upper mantle (~40–50 km depth) Q decreases and in particular the high frequency Q _S (f > 9 Hz) has values similar to those estimated for the shallow layer of the crust.  相似文献   

Probability Distribution of Precipitation Extremes over the Yangtze River Basin   总被引：2，自引：0，他引：2  

Su Buda  Marco Gemmer  Jiang Tong  Ren Guoyu 《气候变化研究进展》2008,4(00):27-31

 Based on the daily observational precipitation data of 147 stations in the Yangtze River basin for 1960-2005, and the projected daily data of 79 grids from ECHAM5/MPI-OM in the 20th century, time series of precipitation extremes which contain annual maximum (AM) and Munger index (MI) were constructed. The distribution feature of precipitation extremes was analyzed based on the two index series. Research results show that (1) the intensity and probability of extreme heavy precipitation are higher in the middle Mintuo River sub-catchment, the Dongting Lake area, the mid-lower main stream section of the Yangtze River, and the southeastern Poyang Lake sub-catchment; whereas, the intensity and probability of drought events are higher in the mid-lower Jinsha River sub-catchment and the Jialing River sub-catchment; (2) compared with observational data, the averaged value of AM is higher but the deviation coefficient is lower in projected data, and the center of precipitation extremes moves northwards; (3) in spite of certain differences in the spatial distributions of observed and projected precipitation extremes, by applying General Extreme Value (GEV) and Wakeby (WAK) models with the method of L-Moment Estimator (LME) to the precipitation extremes, it is proved that WAK can simulate the probability distribution of precipitation extremes calculated from both observed and projected data quite well. The WAK could be an important function for estimating the precipitation extreme events in the Yangtze River basin under future climatic scenarios.  相似文献   

Indentation of a continent with a built-in thickness change: experiment and nature     

Dimitrios Sokoutis  Marco Bonini  Sergei Medvedev  Mario Boccaletti  Christopher J. Talbot  Hemin Koyi 《Tectonophysics》2000,320(3-4):243-270

Orogens oblique to the direction of plate convergence are currently attributed to obliquity between the margins of one or both of the sutured continents to their direction convergence. We use a single analogue experiment and natural examples to illustrate a potential additional factor: variations in strength of the indented continent at a high angle to the convergence direction. The wavelengths of structures in laterally shortened lithosphere depend on the strength of the most competent layers. Lateral variations in crustal thickness must therefore lead to structures oblique to any applied lateral compression.

An analogue experiment was performed to explore this phenomenon. A two-layer ‘indented continent’ was modelled by a brittle upper crust of sand above a lower crust of high-viscosity polymer floating on a single layer of low-viscosity syrup representing the mantle. The well-known strike-slip structures allowing lateral escape to distant weak boundaries were hindered by lateral boundaries in front of the indenter. This allowed us to focus on the effects of a thickness change built into the ‘indented continent’ along a zone parallel to the direction in which a vertical rigid wall advancing at a steady rate represented the indenter. Vertical escape led to an ‘orogenic belt’ oblique to the advancing wall; this obliquity influences subsequent lateral escape. Model scaling and interpretations are based on Extended Thin Sheet Approximation (ETSA) and standard theories of faulting.

Four sectors of the Alpine–Himalayan orogen (Iran, Tunisia, the Eastern Alps and the Himalaya) are oblique to the continental convergence direction, and we point to thickness changes at high angles to the suture that may account for this geometry. As crustal thicknesses north of oblique sectors of the Himalayas are not yet known, we speculate on them.

We infer from the main difference between our experiment and all our examples chosen from nature that vertical orogenic escape was oblique to our model suture but can be parallel to natural sutures.  相似文献   

Signs of power: Fascist urban iconographies in Ethiopia (1930s–1940s)     

Marco Antonsich 《GeoJournal》2000,52(2):325-338

The aim of the present paper is to compare two different patterns of urban iconographies in Ethiopia during 1930s: the one of the Amhara – the traditionally Ethiopian dominant ethnic group – and the one of the Italian fascism. The paper gives an historical account of the structure of the Amhara settlements, focusing on the ways the power of their politico-military chiefs, being they the Negus or the Ras, shaped the spatial order of these settlements. When the Italians conquered military Ethiopia in 1936, they started re-shaping this spatial order, erasing the signs of the previous power and imposing their new iconographic apparatus. This was mainly done through urban planning which was devised to `write' the Fascist concepts of progress, order, hierarchy, and racial segregation on the territory. Owing to the short duration of the occupation, the poor material conditions of the colony and the lack of financial resources, such town-planning projects turned out to be just a political rhetoric exercise.  相似文献