Incorporating circulation statistics in bias correction of GCM ensembles: hydrological application for the Rhine basin     

Christiana Photiadou  Bart van den Hurk  Aarnout van Delden  Albrecht Weerts 《Climate Dynamics》2016,46(1-2):187-203

An adapted statistical bias correction method is introduced to incorporate circulation-dependence of the model precipitation bias, and its influence on estimated discharges for the Rhine basin is analyzed for a historical period. The bias correction method is tailored to time scales relevant to flooding events in the basin. Large-scale circulation patterns (CPs) are obtained through Maximum Covariance Analysis using reanalysis sea level pressure and high-resolution precipitation observations. A bias correction using these CPs is applied to winter and summer separately, acknowledging the seasonal variability of the circulation regimes in North Europe and their correlation with regional precipitation rates over the Rhine basin. Two different climate model ensemble outputs are explored: ESSENCE and CMIP5. The results of the CP-method are then compared to observations and uncorrected model outputs. Results from a simple bias correction based on a delta factor (NoCP-method) are also used for comparison. For both summer and winter, the CP-method offers a statistically significant improvement of precipitation statistics for subsets of data dominated by particular circulation regimes, demonstrating the circulation-dependence of the precipitation bias. Uncorrected, CP and NoCP corrected model outputs were used as forcing to a hydrological model to simulate river discharges. The CP-method leads to a larger improvement in simulated discharge in the Alpine area in winter than in summer due to a stronger dependence of Rhine precipitation on atmospheric circulation in winter. However, the NoCP-method, in comparison to the CP-method, improves the discharge estimations over the entire Rhine basin.  相似文献   

A study of quasi-millennial extratropical winter cyclone activity over the Southern Hemisphere     

Lan Xia  Hans von Storch  Frauke Feser  Jian Wu 《Climate Dynamics》2016,47(7-8):2121-2138

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Betrachtungen über die Konstruktionsgrundlagen von Strahlungsumsatzmessern und Beschreibung einer einfachen Form dieses Gerätes     

F. Albrecht 《Theoretical and Applied Climatology》1949,1(3-4):373-387

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2-D and 3-D modelling of wide-angle seismic data: an example from the Vøring volcanic passive margin     

Stéphane Rouzo  Frauke Klingelhöfer  Hélène Jonquet-Kolstø  Ridvan Karpuz  Karl Kravik  Rolf Mjelde  Yoshio Murai  Thomas Raum  Hideki Shimamura  Paul Williamson  Louis Géli 《Marine Geophysical Researches》2006,27(3):181-199

This study presents the modelling of 2-D and 3-D wide-angle seismic data acquired on the complex, volcanic passive margin of the Vøring Plateau, off Norway. Three wide-angle seismic profiles were shot and recorded simultaneously by 21 Ocean Bottom Seismometers, yielding a comprehensive 3-D data set, in addition to the three in-line profiles. Coincident multi-channel seismic profiles are used to better constrain the modelling, but the Mesozoic and deeper structures are poorly imaged due to the presence of flood basalts and sills. Velocity modelling reveals an unexpectedly large 30 km basement high hidden below the flood basalt. When interpreted as a 2-D structure, this basement high produces a modelled gravity anomaly in disagreement with the observed gravity. However, both the gravity and the seismic data suggest that the structure varies in all three directions. The modelling of the entire 3-D set of travel times leads to a coherent velocity structure that confirms the basement high; it also shows that the abrupt transition to the slower Cretaceous basin coincides in position and orientation with the fault system forming the Rån Ridge. The positive gravity anomaly over the Rån Ridge originates from the focussed and coincident elevation of the high velocity lower crust and pre-Cretaceous basement. Although the Moho is not constrained by the seismic data, the gravity modelled from the 3-D velocity model shows a better fit along the profiles. This study illustrates the interest of a 3-D acquisition of wide-angle seismic over complex structures and the benefit of the subsequent integrated interpretation of the seismic and gravity data.  相似文献   

Wind-tunnel Modelling of Dispersion from a Scalar Area Source in Urban-Like Roughness     

Frauke Pascheke  Janet F. Barlow  Alan Robins 《Boundary-Layer Meteorology》2008,126(1):103-124

A wind-tunnel study was conducted to investigate ventilation of scalars from urban-like geometries at neighbourhood scale by exploring two different geometries a uniform height roughness and a non-uniform height roughness, both with an equal plan and frontal density of λ _p = λ _f = 25%. In both configurations a sub-unit of the idealized urban surface was coated with a thin layer of naphthalene to represent area sources. The naphthalene sublimation method was used to measure directly total area-averaged transport of scalars out of the complex geometries. At the same time, naphthalene vapour concentrations controlled by the turbulent fluxes were detected using a fast Flame Ionisation Detection (FID) technique. This paper describes the novel use of a naphthalene coated surface as an area source in dispersion studies. Particular emphasis was also given to testing whether the concentration measurements were independent of Reynolds number. For low wind speeds, transfer from the naphthalene surface is determined by a combination of forced and natural convection. Compared with a propane point source release, a 25% higher free stream velocity was needed for the naphthalene area source to yield Reynolds-number-independent concentration fields. Ventilation transfer coefficients w _T /U derived from the naphthalene sublimation method showed that, whilst there was enhanced vertical momentum exchange due to obstacle height variability, advection was reduced and dispersion from the source area was not enhanced. Thus, the height variability of a canopy is an important parameter when generalising urban dispersion. Fine resolution concentration measurements in the canopy showed the effect of height variability on dispersion at street scale. Rapid vertical transport in the wake of individual high-rise obstacles was found to generate elevated point-like sources. A Gaussian plume model was used to analyse differences in the downstream plumes. Intensified lateral and vertical plume spread and plume dilution with height was found for the non-uniform height roughness.  相似文献   

Structural evolution and strike-slip tectonics off north-western Sumatra     

Kai Berglar  Christoph Gaedicke  Dieter Franke  Stefan Ladage  Frauke Klingelhoefer  Yusuf S. Djajadihardja 《Tectonophysics》2010,480(1-4):119-132

Based on new multi-channel seismic data, swath bathymetry, and sediment echosounder data we present a model for the interaction between strike-slip faulting and forearc basin evolution off north-western Sumatra between 2°N and 7°N. We examined seismic sequences and sea floor morphology of the Simeulue- and Aceh forearc basins and the adjacent outer arc high. We found that strike-slip faulting has controlled the forearc basin evolution since the Late Miocene. The Mentawai Fault Zone extends up to the north of Simeulue Island and was most probably connected farther northwards to the Sumatran Fault Zone until the end of the Miocene. Since then, this northern branch jumped westwards, initiating the West Andaman Fault in the Aceh area. The connection to the Mentawai Fault Zone is a left-hand step-over. In this transpressional setting the Tuba Ridge developed. We found a right-lateral strike-slip fault running from the conjunction of the West Andaman Fault and the Tuba Ridge in SSW-direction crossing the outer arc high. As a result, extrusion formed a marginal basin north of Simeulue Island which is tilted eastwards by uplift along a thrust fault in the west. The shift of strike-slip movement in the Aceh segment is accompanied by a relocation of the depocenter of the Aceh Basin to the northwest, forming one major Neogene unconformity. The Simeulue Basin bears two major Neogene unconformities, documenting that differences in subsidence evolution along the northern Sumatran margin are linked to both forearc-evolution related to subduction processes and to deformation along major strike-slip faults.  相似文献   

The relationship between websterite and peridotite in the Balmuccia peridotite massif (NW Italy) as revealed by trace element variations in clinopyroxene   总被引：7，自引：0，他引：7  

Rivalenti  Giorgio  Mazzucchelli  Maurizio  Vannucci  Riccardo  Hofmann  Albrecht W.  Ottolini  Luisa  Bottazzi  Piero  Obermiller  Walter 《Contributions to Mineralogy and Petrology》1995,122(3):275-288

 Field, mineralogical and petrological data are presented on a newly found carbonatite occurrence associated with “kamafugite” lava at Cupaello, central Italy. This carbonatite occurrence is part of the Late Pleistocene Umbria-Latium ultra-alkaline district (ULUD) which extends southwards within the Apennines to Mount Vulture, delineating an important magmatic province along the most peripheral belt of the Tyrrhenian extensional tectonic system. This province is distinct, but probably related genetically with the more abundant and common leucite-bearing assemblages of the Roman Comagmatic Region and represents the first reported occurrence of carbonatite assemblages in the Mediterranean Basin. The Cupaello suite indicates that primary or near-primary mantle silicate melts of “kamafugitic” composition are transitional with Ca-carbonatite liquid and provides direct evidence of immiscibility of carbonatite from “kamafugite” magma. It is inferred that a primary mantle origin of Ca-carbonatites is conditional upon a potential silicate magma that may be coupled with the carbonatite, but may not have reached the surface. The data indicate a strong genetic link between ULUD Ca-carbonatites and some African analogues, supporting the view that their genesis depends on similar source and associated tectonic conditions. Received: 17 January 1995 / Accepted: 14 June 1995  相似文献   

Exploring changes in hydrogeological risk awareness and preparedness over time: a case study in northeastern Italy     

E. Mondino  A. Scolobig  M. Borga  F. Albrecht  J. Mård  P. Weyrich 《水文科学杂志》2020,65(7):1049-1059

ABSTRACT

Hydrogeological hazards are increasingly causing damage worldwide due to climatic and socio-economic changes. Building resilient communities is crucial to reduce potential losses. To this end, one of the first steps is to understand how people perceive potential threats around them. This study aims at exploring how risk awareness of, and preparedness to, face hydrological hazards changes over time. A cohort study was carried out in two villages in the northeastern Italian Alps, Romagnano and Vermiglio, affected by debris flows in 2000 and 2002. Surveys were conducted in 2005 and 2018, and the results compared. The survey data show that both awareness and preparedness decreased over time. We attribute this change to the fact that no event had occurred in a long time and to a lack of proper risk communication strategies. The outcomes of this study contribute to socio-hydrological modelling by providing empirical data on human behaviour dynamics.  相似文献   

Direct-coupled thermocouple amplifiers for measurements in geophysics and meteorology     

Hans J. Albrecht 《Pure and Applied Geophysics》1956,34(1):196-206

Summary Following a brief discussion of known methods of electronic amplification, this paper describes new thermocouple amplifiers using junction-type transistors, and their theoretical and practical design. The apparatus amplify a thermocouple voltage or other input signals of any impedance such that an ordinary pointer-type galvanometer or recorder can be used as indicator. The problem of temperature compensation has also been dealt with. Details of two transistor amplifiers are given as examples. In conclusion geophysical applications are mentioned.

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Zusammenfassung Nach einer kurzen Behandlung bekannter elektronischer Verstärkungsmethoden beschreibt diese Arbeit neuartige Thermoelementverstärker mit Schichttransistoren und ihre theoretische und praktische Konstruktion. Die Geräte verstärken eine Thermoelementspannung oder andere Eingangssignale irgendeiner Impedanz, sodass ein normales Zeigergalvanometer oder Registriergerät als Anzeigegerät benutzt werden kann. Ausserdem wird die Frage der Temperaturkompensation behandelt. Einzelheiten von zwei Transistorverstärkern werden als Beispiele eingehend beschrieben. Abschliessend werden geophysikalische Anwendungen erwähnt.

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Age determinations in the Precambrian basement of the Wadi Araba area,southwest Jordan     

Ghaleb Jarrar  Albrecht Baumann  Horst Wachendorf 《Earth and Planetary Science Letters》1983,63(2):292-304

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