Why Is the Climate Forcing of Sulfate Aerosols So Uncertain?   总被引：2，自引：0，他引：2  

Hu Rongming  Serge Planton  Michel Déque  Pascal Marquet  Alain Braun 《大气科学进展》2001,18(6):1103-1120

l. IntroductionAlthough the aerosol has been recognized as an important factor which has innuence onthe past, present and future climate for a long time, it still has much uncertainty in assessingits climate forcing. The direct radiative forcing of sulfate aerosols has been estimated rangingfrom --0.3 W/ m2 to --0.9 W/ m2 in recent publications (Charlson et al., l992, Kiehl andBriegleb l993; Taylor and Penner 1994, Boucher and Anderson l995, Kieh1 and Rodhe l995;Chuang et al., l997, Penne…  相似文献   

Modelling landscape evolution on geological time scales: a new method based on irregular spatial discretization   总被引：5，自引：0，他引：5  

Jean Braun  & Malcolm Sambridge 《Basin Research》1997,9(1):27-52

We present simulations of large-scale landscape evolution on tectonic time scales obtained from a new numerical model which allows for arbitrary spatial discretization. The new method makes use of efficient algorithms from the field of computational geometry to compute the set of natural neighbours of any irregular distribution of points in a plane. The natural neighbours are used to solve geomorphic equations that include erosion/deposition by channelled flow and diffusion. The algorithm has great geometrical flexibility, which makes it possible to solve problems involving complex boundaries, radially symmetrical uplift functions and horizontal tectonic transport across strike-slip faults. The algorithm is also ideally suited for problems which require large variations in spatial discretization and/or self-adaptive meshing. We present a number of examples to illustrate the power of the new approach and its advantages over more 'classical' models based on regular (rectangular) discretization. We also demonstrate that the synthetic river networks and landscapes generated by the model obey the laws of network composition and have scaling properties similar to those of natural landscapes. Finally we explain how orographically controlled precipitation and flexural isostasy may be easily incorporated in the model without sacrificing efficiency.
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Interactive Knowledge Generation in Urban Green Building Transitions     

Bérénice Preller  Julia Affolderbach  Christian Schulz  Sebastian Fastenrath  Boris Braun 《The Professional geographer》2017,69(2):214-224

Knowledge coproduction between practitioners and scientists offers promising opportunities for the emerging research field of the geography of sustainability transitions. Drawing on experiences from an international research project on urban green building transitions, this article explores the potentials and challenges of interactive and collaborative knowledge generation methods in understanding sustainability transitions. Our results show that ongoing engagement with local experts and practitioners through interactive World Café workshops and follow-up exchanges allows for a better understanding of the research context and knowledge exchange to all participants involved in the research process.  相似文献   

A new probabilistic approach to estimating marine gastropod densities from baited traps          下载免费PDF全文

Jennifer Coston‐Guarini  Jean‐Marc Guarini  Frederike Ricarda Boehm  Thomas R. H. Kerkhove  Frances C. Rivera  Karim Erzini  François Charles  Tim Deprez  Laurent Chauvaud 《Marine Ecology》2018,39(3)

A new probabilistic approach is proposed to assess muricid species population abundances at scales relevant to both Ancient and Modern coastal fisheries. Motivated by the long‐term goal of reconstructing the dynamics of exploited murex populations during Antiquity, the objective was to estimate the population density of the banded dye‐murex, Hexaplex trunculus (Linnaeus, 1758) from successive captures with baited traps, using a method similar to the technique employed in the Mediterranean purple dye industry. The stochastic model developed simulates cumulative captures while accounting for high variability. It was calibrated with data acquired during a field trapping experiment (Crete Island, Greece). Traps’ catchability and Effective Area of Attraction (EAA) were estimated using the individual speed and behavioural response towards bait from laboratory experiments. Average density of H. trunculus was estimated as 2.2 ± 1.4 SE individuals per square metre, with no significant differences between seagrass and rocky habitats. The clearing time of successive capture experiments averaged 84 ± 6 SE hr. Clearing ca. 0.4 ha of subtidal area would be necessary to produce ca. 1.0 g of pure Tyrian purple pigment. The method described is generalizable to making population abundance estimates for similar groups, such as whelks, in modern fisheries.  相似文献   

Resolution of MRS applied to the characterization of hard-rock aquifers   总被引：4，自引：0，他引：4  

Legchenko A  Descloitres M  Bost A  Ruiz L  Reddy M  Girard JF  Sekhar M  Mohan Kumar MS  Braun JJ 《Ground water》2006,44(4):547-554

The performance of the Magnetic Resonance Sounding (MRS) method applied to the investigation of heterogeneous hard-rock aquifers was studied. It was shown using both numerical modeling and field measurements that MRS could be applied to the investigation of the weathered part of hard-rock aquifers when the product of the free water content multiplied by the thickness of the aquifer is >0.2 (for example, 10-m-thick layer with a 2% water content). Using a currently available one-dimensional MRS system, the method allows the characterization of two-dimensional subsurface structures with acceptable accuracy when the size of the subsurface anomaly is equal to or greater than the MRS loop. However, the fractured part of hard-rock aquifers characterized by low effective porosity (<0.5%) cannot be resolved using currently available MRS equipment. It was found that shallow water in the weathered part of the aquifer may screen MRS signals from deeper water-saturated layers, thus further reducing the possibility of investigating deeper fractured aquifers. A field study using the NUMIS(plus) MRS system developed by IRIS Instruments was carried out on an experimental watershed in southern India. A heterogeneous unconfined aquifer in a gneissic formation was successfully localized, and MRS results were confirmed by drilling shortly after the geophysical study. The top of the aquifer revealed by MRS was found to be in a good agreement with observed static water level measurements in boreholes.  相似文献   

Application of uncertainty visualization methods to meteorological trajectories     

Ryan A. Boller  Scott A. Braun  Jadrian Miles  David H. Laidlaw 《Earth Science Informatics》2010,3(1-2):119-126

We present an application of uncertainty visualization to air parcel trajectories generated from a global meteorological model. We derive an approximation of advection uncertainty due to interpolation and incorporate this uncertainty into our visualization of trajectories. Our work enables efficient visual pruning of unlikely results, especially in regions of atmospheric shear, potentially reducing erroneous interpretations. Finally, we apply these methods to a real-world meteorological problem to demonstrate its use.  相似文献   

A GIS-BASED GLACIER INVENTORY FOR THE ANTARCTIC PENINSULA AND THE SOUTH SHETLAND ISLANDS——A FIRST CASE STUDY ON KING GEORGE ISLAND   总被引：1，自引：0，他引：1  

Matthias Braun  F.Rau  Jefferson Cardia Si“非汉字字符”mes 《地球空间信息科学学报》2001,4(2)

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＷｏｒｋｉｎｇＧｒｏｕｐｏｎＧｅｏｄｅｓｙａｎｄＧｅｏｇｒａｐｈｉｃＩｎｆｏｒｍａｔｉｏｎ (ＷＧ＿ＧＧＩ)ｏｆｔｈｅＳｃｉｅｎｔｉｆｉｃＣｏｍｍｉｔ ｔｅｅｏｎＡｎｔａｒｃｔｉｃＲｅｓｅａｒｃｈ (ＳＣＡＲ )ｌａｕｎｃｈｅｄｔｈｅｐｒｏｊｅｃｔＫｉｎｇＧｅｏｒｇｅＩｓｌａｎｄＧＩＳ (ＫＧＩＳ) .Ｉｎｏｒｄｅｒｔｏｐｒｏｖｉｄｅａｎｏｐｅｒａｔｉｏｎａｌｓｙｓｔｅｍ ,ａｄａｔａｍｏｄｅｌ,ｄａｔａａｃｃｕｒａｃｙｓｔａｎｄａｒｄｓａｎｄａｄａｔａｉｎｖｅｎｔｏｒｙｈａｖ…  相似文献   

Anwendung der Theorie stochastischer Prozesse auf Wassergütedaten     

P. Braun 《洁净——土壤、空气、水》1973,1(1):71-82

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Investigation of the lithosphere beneath the Vogelsberg volcanic complex with P-wave travel time residuals     

T. Braun  H. Berckhemer 《International Journal of Earth Sciences》1993,82(1):20-29

With the aim of investigating the P-wave velocity structure below the Tertiary volcano Vogelsberg, a network of 10 mobile short period seismograph stations was installed in May 1987 for a period of 20 months. P-Wave travel time residuals relative to the station Kleiner Feldberg/Taunus (TNS) were determined for 168 seismic events using the Jeffreys - Bullen travel time tables. At all stations the relative residuals showed a positive sign, indicating a low velocity zone beneath the Vogelsberg. Maxima were found in the northern part of the Vogelsberg (station VAD +0.5 s) and in the region of the Amöneburger Basin (station RAU +0.28 s).The travel time residuals were inverted using the tomographic inversion method of Aki et al. (1977). The slowness perturbations of the single blocks were calculated relative to a crustal and upper mantle model of the Rhenish Massif. The results show an intracrustal low velocity body (about –9%) striking in a Variscan direction and underlying the north-eastern part of the Vogelsberg, and another velocity minimum (about – 6%) in the region of the Am6neburger Basin. In the lower crust and the upper mantle the velocities are reduced by about 4% relative to the starting model.The Variscan alignment of the low velocity zone under the Vogelsberg correlates with results of other geological studies. It can be assumed that during the rifting phase of the Upper Rhinegraben Variscan lineations have been reactivated, favouring uprising of magma along these old structures. The position and extension of the low velocity zone correlate with the assumed sediment distributions in the area of investigation. This may account for about one-half of the observed anomaly. The reason for the velocity reduction of about 4% in the entire underground region of the Vogelsberg down to a depth of about 70 km can be explained by the intensive fracturing of the lithosphere, caused by thermal and pressure gradients during the magma eruption process.  相似文献   

Buchbesprechungen     

Rudolf Braun  A. Preissmann  H. Ambübl  M. Schüepp 《Aquatic Sciences - Research Across Boundaries》1955,17(2):524-528

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