A summary of the PRUDENCE model projections of changes in European climate by the end of this century   总被引：3，自引：0，他引：3  

Jens Hesselbjerg Christensen  Ole Bøssing Christensen 《Climatic change》2007,81(1):7-30

An overview of the PRUDENCE fine resolution climate model experiments for Europe is presented in terms of their climate change signals, in particular 2-meter temperature and precipitation. A comparison is made with regard to the seasonal variation in climate change response of the different models participating in the project. In particular, it will be possible to check how representative a particular PRUDENCE regional experiment is of the overall set in terms of seasonal values of temperature and precipitation. This is of relevance for such further studies and impact models that for practical reasons cannot use all the PRUDENCE regional experiments. This paper also provides some guidelines for how to select subsets of the PRUDENCE regional experiments according to such main sources of uncertainty in regional climate simulations as the choice of the emission scenario and of the driving global climate model.  相似文献   

Development of python-FALL3D: a modified procedure for modelling volcanic ash dispersal in the Asia-Pacific region     

A. N. Bear-Crozier  Nugraha Kartadinata  Anjar Heriwaseso  Ole Nielsen 《Natural Hazards》2012,64(1):821-838

Volcanic ash is the most widespread of all volcanic hazards and has the potential to affect hundreds of thousands, or even millions, of people in the densely populated islands of Indonesia. There is limited information available for this region on the hazard posed by volcanic ash, particularly from volcanoes that have not erupted in recent times. There is a need for computational models capable of accurately predicting volcanic ash dispersal at ground level when coupled with field observations of historical or ongoing eruptive activity. To maximise the effectiveness of such models, they should be readily accessible, easy to use and well tested. Geoscience Australia in collaboration with the Australia-Indonesia Facility for Disaster Reduction and the Indonesian Centre for Volcanology and Geohazard Mitigation has collaboratively adapted an existing open-source volcanic ash dispersion model for use in Indonesia. The core model is the widely used, open-source volcanic ash dispersion model FALL3D. A Python wrapper (name here python-FALL3D) has been developed, which modifies the modelling procedure of FALL3D in order to simplify its use for those with little or no background in computational modelling. The modified procedure does not alter the core functionality of FALL3D, but simplifies the modelling procedure by streamlining the installation process, automating both the pre-processing of input meteorological datasets and configuring and executing each utility program in a single-step process. An application example was presented using python-FALL3D for an active volcano in West Java, Indonesia. The example showed that communities located on the western side of Gunung Gede are always susceptible to volcanic ash ground loading regardless of the seasonal variations in wind conditions, whereas communities on the eastern side of Gunung Gede have a marked increase in susceptibility to ground loading during rainy season conditions when prevailing winds include a strong easterly component.  相似文献   

Deglaciation chronology,sea-level changes and environmental changes from Holocene lake sediments of Germania Havn Sø, Sabine Ø, northeast Greenland     

Ole Bennike  Bernd Wagner 《Quaternary Research》2012,78(1):103-109

Germania Havn Sø is located at the outermost coast of northeastern Greenland. According to radiocarbon dating, the lake basin was deglaciated in the early Holocene, around 11,000 cal yr BP. At that time the lake was a marine bay, but the lake was isolated soon after deglaciation at ~ 10,600 cal yr BP. The marine fauna was species-poor, indicating harsh conditions with a high sedimentation rate and lowered salinity due to glacial meltwater supply. The pioneer vegetation around the lake was dominated by mosses and herbs. Deposition of relatively coarse sediments during the early Holocene indicates erosion of the newly deglaciated terrain. Remains of the first woody plant (Salix herbacea) appear at 7600 cal yr BP and remains of other woody plants (Salix arctica, Dryas octopetala, Cassiope tetragona and Empetrum nigrum) appear around one millennium later. Declining concentrations of D. octopetala and the caddis fly Apatania zonella in the late Holocene probably imply falling summer temperatures. Only moderate changes in the granulometric and geochemical record during the Holocene indicate relatively stable environmental settings in the lake, which can probably be explained by its location at the outer coast and the buffering effect of the neighboring ocean.  相似文献   

Memory-Efficient Categorical Multi-point Statistics Algorithms Based on Compact Search Trees   总被引：1，自引：1，他引：0  

Tuanfeng Zhang  Stein Inge Pedersen  Christen Knudby  David McCormick 《Mathematical Geosciences》2012,44(7):863-879

Multi-point statistics (MPS) has emerged as an advanced geomodeling approach. A practical MPS algorithm named snesim (simple normal equations simulation), which uses categorical-variable training images, was proposed in 2001. The snesim algorithm generates a search tree to store the occurrence statistics of all patterns in the training image within a given set of search templates before the simulation proceeds. The snesim search tree concept makes MPS simulation central processing unit efficient but consumes large amounts of memory, particularly when three-dimensional training images contain complex patterns and when a large search template is required to ensure optimal reproduction of the image patterns. To crack the memory-restriction bottleneck, we have developed a compact search tree that contains the same information but reduces memory cost by one order of magnitude. Furthermore, the compact structure also accelerates MPS simulation significantly. Such remarkable improvement makes MPS a more practical tool to use in building the large and complex three-dimensional facies models required in the oil and gas industry.  相似文献   

The pseudometeorite Angara     

Holger Pedersen 《Meteoritics & planetary science》2013,48(6):1091-1095

Several pallasites are known to have formed strewn fields with multiple fragments. Therefore, it seems possible that the famous Krasnojarsk pallasite—the Pallas Iron of 687 kg—could have been accompanied by one or more additional fragments that had not been recovered due to incomplete observations from the overgrown and remote place of fall. During a survey for literature accounts of distant fragments in such a hypothetical strewn field, a report of native iron was found, dating to 1847. The fragments of nickel‐free iron—amounting to at least a few kg—had been recovered 1836–1843 during placer gold mining north of the Angara River. The position of these finds is coincident with Burovaya, Murozhna, and Uderei, the three known fragments of the pseudometeorite Angara, all collected in 1885.  相似文献