Introduction     

Renata Dmowska  Göran Ekström 《Pure and Applied Geophysics》1994,142(1):1-2

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Extreme precipitation in WRF during the Newcastle East Coast Low of 2007     

James B. Gilmore  Jason P. Evans  Steven C. Sherwood  Marie Ekström  Fei Ji 《Theoretical and Applied Climatology》2016,125(3-4):809-827

In the context of regional downscaling, we study the representation of extreme precipitation in the Weather Research and Forecasting (WRF) model, focusing on a major event that occurred on the 8^th of June 2007 along the coast of eastern Australia (abbreviated “Newy”). This was one of the strongest extra-tropical low-pressure systems off eastern Australia in the last 30 years and was one of several storms comprising a test bed for the WRF ensemble that underpins the regional climate change projections for eastern Australia (New South Wales/Australian Capital Territory Regional Climate Modelling Project, NARCliM). Newy provides an informative case study for examining precipitation extremes as simulated by WRF set up for regional downscaling. Here, simulations from the NARCliM physics ensemble of Newy available at ～10 km grid spacing are used. Extremes and spatio-temporal characteristics are examined using land-based daily and hourly precipitation totals, with a particular focus on hourly accumulations. Of the different physics schemes assessed, the cumulus and the boundary layer schemes cause the largest differences. Although the Betts-Miller-Janjic cumulus scheme produces better rainfall totals over the entire storm, the Kain-Fritsch cumulus scheme promotes higher and more realistic hourly extreme precipitation totals. Analysis indicates the Kain-Fritsch runs are correlated with larger resolved grid-scale vertical moisture fluxes, which are produced through the influence of parameterized convection on the larger-scale circulation and the subsequent convergence and ascent of moisture. Results show that WRF qualitatively reproduces spatial precipitation patterns during the storm, albeit with some errors in timing. This case study indicates that whilst regional climate simulations of an extreme event such as Newy in WRF may be well represented at daily scales irrespective of the physics scheme used, the representation at hourly scales is likely to be physics scheme dependent.  相似文献   

Designing laboratory wind simulations using artificial neural networks     

Josip Križan  Goran Gašparac  Hrvoje Kozmar  Oleg Antonić  Branko Grisogono 《Theoretical and Applied Climatology》2015,120(3-4):723-736

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The impact of interactive visualization on trade-off-based geospatial decision-making     

Goran Milutinović  Ulla Ahonen-Jonnarth  Stefan Seipel  Sven Anders Brandt 《International journal of geographical information science》2019,33(10):2094-2123

In a previous work we developed GISwaps, a novel method for geospatial decision-making based on Even Swaps. In this paper, we present the results of an evaluation of a visualization framework integrated with this method, implemented within a decision support system. This evaluation is based on two different studies. In the quantitative study, 15 student participants used GISwaps with no visual features, and 15 participants used GISwaps with the integrated visual framework, as the tool in a solar farm site location case study. The results of the quantitative evaluation show positive impact of the visualization in terms of increased coherency in trade-offs. The results also show a statistically significant difference in average trade-off values between the groups, with users from the non-visual group setting on average 20% higher trade-off values compared with the users in the visual group. In the qualitative study, we had one expert in GIS, two experts in decision-making and two experts in solar energy as a focus user group. Data in this study were obtained by observations and semi-structured interviews with the participants. The impact of the visualization framework was assessed positively by all participants in the expert group.  相似文献   

Global Event Location with Full and Sparse Data Sets Using Three-dimensional Models of Mantle P-wave Velocity     

M. Antolik  G. Ekström  A.M. Dziewonski 《Pure and Applied Geophysics》2001,158(1-2):291-317

—?In order to improve on the accuracy of event locations at teleseismic distances it is necessary to adequately correct for lateral variations in structure along the ray paths, either through deterministic model-based corrections, empirical path/station corrections, or a combination of both approaches. In this paper we investigate the ability of current three-dimensional models of mantle P-wave velocity to accurately locate teleseismic events. We test four recently published models; two are parameterized in terms of relatively long-wavelength spherical harmonic functions up to degree 12, and two are parameterized in terms of blocks of constant velocity which have a dimension of a few hundreds of km. These models, together with detailed crustal corrections, are used to locate a set of 112 global test events, consisting of both earthquakes and explosions with P-wave travel-time data compiled by the Internation al Seismological Centre (ISC). The results indicate that the supposedly higher resolution block models do not improve the accuracy of teleseismic event locations over the longer wavelength spherical harmonic models. For some source locations the block models do not predict the range of observed travel-time residuals as well as the longer wavelength models. The accuracy of the locations largely varies randomly with geographic position although events in central Asia are particularly well located. We also tested the effect of reduced data sets on the locations. Multiple location iterations using 30 P-wave travel times indicate that teleseismic events may be located within an area of 1000?km² of the true location 66% of the time with only the model-based corrections, and increasing to 75% if calibration information is available. If as few as 8 phases are available then this is possible only 50% of the time. Further refinement in models and/or procedure, such as the addition of P _n phases, azimuth data, and consideration of P-wave anisotropy may provide further improvement in the teleseismic location of small events.  相似文献   

Sphalerite composition in relation to the stress distribution of a boudinage     

Sandor Berglund  Tom K. Ekström 《Lithos》1974,7(1):1-6

The content of FeS in sphalerites from different parts of a boudinage is compared with the theoretical stress pattern. The calculated differences in stress correspond to less than one mole percent FeS and are often masked by the small variations in the fugacity of sulfur.  相似文献   

The July 2007 rock and ice avalanches at Mount Steele, St. Elias Mountains, Yukon, Canada   总被引：1，自引：0，他引：1  

Panya S. Lipovsky  Stephen G. Evans  John J. Clague  Chris Hopkinson  Réjean Couture  Peter Bobrowsky  Göran Ekström  Michael N. Demuth  Keith B. Delaney  Nicholas J. Roberts  Garry Clarke  Andrew Schaeffer 《Landslides》2008,5(4):445-455

A large rock and ice avalanche occurred on the north face of Mount Steele, southwest Yukon Territory, Canada, on July 24, 2007. In the days and weeks preceding the landslide, several smaller avalanches initiated from the same slope. The ice and rock debris traveled a maximum horizontal distance 5.76 km with a maximum vertical descent of 2,160 m, leaving a deposit 3.66 km² in area on Steele Glacier. The seismic magnitude estimated from long-period surface waves (M _s) is 5.2. Modeling of the waveforms suggests an estimated duration of approximately 100 s and an average velocity of between 35 and 65 m/s. This landslide is one of 18 large rock avalanches known to have occurred since 1899 on slopes adjacent to glaciers in western Canada. We describe the setting, reconstruct the event chronology and present a preliminary characterization of the Mount Steele ice and rock avalanches based on field reconnaissance, analysis of seismic records and an airborne LiDAR survey. We also present the results of a successful dynamic simulation for the July 24 event.  相似文献   

Electrochemical Degradation of Triketone Herbicides and Identification of Their Main Degradation Products          下载免费PDF全文

Milica Jović  Dragan Manojlović  Dalibor Stanković  Uroš Gašić  Dejan Jeremić  Ilija Brčeski  Goran Roglić 《洁净——土壤、空气、水》2015,43(7):1093-1099

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Ground-based astrometric observations of latitude for improved reference frame     

Goran Damljanovi? 《Planetary and Space Science》2008,56(14):1896-1902

The Commission 19 (Earth Rotation) of the International Astronomical Union—IAU established the Working Group on Earth Rotation in the Hipparcos Reference Frame—WG ERHRF at 1995 to collect the optical observations of latitude and universal time variations, made during 1899.7-1992.0 in line with Earth orientation programmes (to derive Earth Orientation Parameters—EOP), with Dr. Jan Vondrák (Astronomical Institute of Academy of Sciences of the Czech Republic, Prague) as the head of WG ERHRF. Dr. Vondrák collected about 4.4 million optical observations of latitude/universal time variations made at 33 observatories. These data were used for EOP investigations, Hipparcos Catalogue—radio sources connection, etc. Nowadays, it is used to correct the positions and proper motions of stars of Hipparcos Catalogue (as an optical reference frame) using ground-based observations of some Hipparcos stars. After Hipparcos Catalogue, some new astrometric catalogues appeared (as ARIHIP, EOC-2, etc.) with better accuracy of proper motions. We use the latitude observations made by visual zenith-telescope (ZT), as classical astrometric instrument, at seven observatories (all over the world) of International Latitude Service—ILS. The observations were used in the programmes of monitoring the Earth orientation during the 20th century. We received the data from Dr. Vondrák via private communication. The observatories are Carloforte—CA, Cincinnati—CI, Gaithersburg—GT, Kitab—KZ, Mizusawa—MZZ, Tschardjui—TS and Ukiah—UK. The task is to improve proper motions in declination of the observed Hipparcos stars. The original method was developed. We removed from the instantaneous observed latitudes, all known effects (polar motion and some local instrumental errors), and the corrected latitudes were then the input data to calculate the corrections of Hipparcos proper motions in declination using the least squares method—LSM with the linear model. We did an improvement of Hipparcos proper motions in declination via mentioned latitude variations with time by using a long-term (a few decades) visual zenith-telescope data of ILS. The calculated results were compared with the ARIHIP and EOC-2 data, and the consistency were good. The main steps of the calculations and some of the results are presented here.  相似文献   

Reactivity of dissolved organic matter in response to acid deposition     

Sara M. Ekström  Margareta Sandahl  P. Anders Nilsson  Dan B. Kleja  Emma S. Kritzberg 《Aquatic Sciences - Research Across Boundaries》2016,78(3):463-475

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