A note on frame transformations with applications to geodetic datums   总被引：1，自引：0，他引：1  

Tomás?SolerEmail author  John?Marshall 《GPS Solutions》2003,7(1):23-32

Rigorous equations in compact symbolic matrix notation are introduced to transform coordinates and velocities between ITRF frames and modern GPS-based geocentric geodetic datums. The theory is general but, after neglecting higher than second-order terms, it is shown that the equations revert to the formulation currently applied in most major continental datums. We discuss several examples: the North American Datum of 1983 (NAD83), the European Terrestrial Reference System of 1989 (ETRS89), the Geodetic Datum of Australia of 1994 (GDA94), and the South American Geocentric Reference System (SIRGAS). Electronic Publication  相似文献   

Automatic Location of Swarm Earthquakes from Local Network Data     

Fischer  Tomáš 《Studia Geophysica et Geodaetica》2003,47(1):83-98

An advanced method of automated seismic phase picking and exact location and magnitude determination of swarm micro-earthquakes from local network data is presented. The phase picker is applied in two steps: first, S-wave groups are identified using a polarisation detector, and then corresponding P-wave groups are searched for. The times of maximum P- and S-amplitudes are then used as starting points for the determination of accurate P- and S-arrival times. The maximum S-wave amplitudes are utilised for determining local magnitudes. The whole procedure is checked by simultaneous preliminary hypocentre location providing estimates of local magnitudes and a compatibility check of the candidate P- and S-phases. The closest station to the earthquake cluster is used as a master, and the phase search at the remaining stations is governed by the P- and S-phases identified at the master station. Thanks to the use of apriori information on the approximate position of hypocentres, the procedure is also capable of picking the individual P- and S-phases of sequences of overlapping swarm events. The performance of the procedure was tested by comparison of the automatically and interactively created catalogues of the January 1997 NW-Bohemia micro-earthquake swarm. With stations located at epicentral distances between 0 and 20 km, the difference between hypocentre coordinates obtained by automatic and interactive processing did not exceed 80 m for 86% events. All events above magnitude 0.5 were identified, and the automatically determined polarity of first P-wave motion proved to be correct in 89% of them.  相似文献   

Köppen Climate Types in Observed and Simulated Climates     

Kalvová  Jaroslava  Halenka  Tomáš  Bezpalcová  Klára  Nemešová  Ivana 《Studia Geophysica et Geodaetica》2003,47(1):185-202

The Köppen climate classification was applied to the observed gridded climatological sets and the outputs of four general circulation models (GCMs) over the continents of the Earth. All data had been acquired via the Data Distribution Centre established by the Intergovernmental Panel on Climate Change. The ability of the GCMs to simulate the Köppen climate zones identified in the real data was explored and possible future (global warming) changes in the climate types' distribution for each GCM were assessed. Differences in the area distributions derived from the GCMs' recent climate simulations give evidence about uncertainties generally involved in climate models. As to the global warming simulations, all GCM projections of warming climate (horizon 2050) show that the zones representing tropical rain climates and dry climates become larger, and the zones identified with boreal forest and snow climates together with the polar climates are smaller.  相似文献   

On the Integrability of Limited-Area Numerical Weather Prediction Model ALADIN over Extended Time Periods     

Huth  Radan  Mládek  Richard  Metelka  Ladislav  Sedlák  Pavel  Huthová  Zuzana  Kliegrová  Stanislava  Kyselý  Jan  Pokorná  Lucie  Halenka  Tomáš  Janoušek  Martin 《Studia Geophysica et Geodaetica》2003,47(4):863-873

This note summarizes results of the first integration of regional numerical weather prediction model ALADIN in a climate mode. The ALADIN model, developed in an international cooperation led by Météo France, is operationally used for weather prediction. The grid step of the model is 12 km; the integration domain covers a major part of Europe. A one-month-long run has been performed with this model on observed boundary conditions (represented by assimilations by the global model ARPEGE). It is demonstrated that no excessive error is generated and accumulated in the model during the integration; hence the model is integrable for extended time periods and may serve a basis for a development towards a regional climate model.  相似文献   

The Linear Coregionalization Model and the Product–Sum Space–Time Variogram     

S. De Iaco  D. E. Myers  D. Posa 《Mathematical Geology》2003,35(1):25-38

The product covariance model, the product–sum covariance model, and the integrated product and integrated product–sum models have the advantage of being easily fitted by the use of marginal variograms. These models and the use of the marginals are described in a series of papers by De Iaco, Myers, and Posa. Such models allow not only estimating values at nondata locations but also prediction in future times, hence, they are useful for analyzing air pollution data, meteorological data, or ground water data. These three kinds of data are nearly always multivariate and because the processes determining the deposition or dynamics will affect all variates, a multivariate approach is desirable. It is shown that the use of marginal variograms for space–time modeling can be extended to the multivariate case and in particular to the use of the Linear Coregionalization Model (LCM) for cokriging in space–time. An application to an environmental data set is given.  相似文献   

On the Dynamics of the Jovian Ionosphere and Thermosphere: III. The Modelling of Auroral Conductivity     

George MillwardSteve Miller  Tom StallardAlan D. Aylward  Nicholas Achilleos 《Icarus》2002,160(1):95-107

Recent work has been concerned with calculating the three-dimensional ion concentrations and Pedersen and Hall conductivities within the auroral region of Jupiter for varying conditions of incident electron precipitation. Using the jovian ionospheric model, we present results that show the auroral ionospheric response to changing the incoming flux of precipitating electrons (for constant initial energy) and also the response to changing the initial energy (for both constant flux and constant energy flux). The results show that, for expected energy fluxes of precipitating particles, the average auroral integrated Pedersen conductivity attains values in excess of 1 mho. In addition, it is shown that electrons with an initial energy of around 60 keV are particularly effective at generating auroral conductivity: Particles of this energy penetrate most effectively to the layer of the jovian ionosphere at which the auroral conductivity is at a maximum.  相似文献   

A New Leak Detection System for Long-Distance Pipelines Utilizing Soil-Gas Techniques     

K.F. Liang  M.C. Tom Kuo 《Ground Water Monitoring & Remediation》2006,26(3):53-59

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GPS/GNSS Current Bibliography     

Tomás Soler 《GPS Solutions》2006,10(1):63-66

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The Natural Hazards Theme of the International Year of Planet Earth     

Tom Beer 《Natural Hazards》2007,42(3):469-480

The United Nations has declared 2008 to be the International Year of Planet Earth. It is being organised under the auspices of the International Union of Geological Sciences and UNESCO. Planning for the International Year of Planet Earth has consisted of establishing 10 major science themes including Hazards. The Hazards Theme is centred around the following key questions: (1) How have humans altered the geosphere, the biosphere and the landscape, thereby creating long-term changes detrimental to life and the environment and triggering certain hazards, while increasing societal vulnerability to geophysical (geological and hydrometeorological) hazards? (2) What technologies and methodologies are required to assess the vulnerability of people and places to hazards and how might these be used at a variety of spatial scales? (3) How do geophysical hazards compare relative to each other regarding current capabilities for monitoring, prediction and mitigation and what can be done in the short-term to improve these capabilities (4) What barriers exist to the utilisation of risk and vulnerability information by governments (and other entities) for risk and vulnerability reduction policies and planning (including mitigation) from each of the geophysical hazards? Following the 26 December 2004 Indian Ocean Tsunami and the UN World Conference on Disaster Reduction held in Kobe, Japan in January 2005, the International Council for Science (ICSU) decided to establish a major research programme and initiative on Natural and Human Induced Environmental Hazards and Disasters that will co-operate with the Hazards theme of the International Year and continue through to 2011.  相似文献   

Detection of iodine monoxide radicals in the marine boundary layer using laser induced fluorescence spectroscopy     

Lisa K. Whalley  Kate L. Furneaux  Tom Gravestock  Helen M. Atkinson  Catherine S. E. Bale  Trevor Ingham  William J. Bloss  Dwayne E. Heard 《Journal of Atmospheric Chemistry》2007,58(1):19-39

A Laser Induced Fluorescence (LIF) instrument has been developed to detect iodine monoxide (IO) radicals in the atmosphere. An all solid-state Nd:YAG pumped Ti:Sapphire laser operating at approximately 445 nm was used to excite the (2,0) band of the IO A²Π_3/2 ← X²Π_3/2 electronic transition, with off-resonance fluorescence in the (2,5) band detected at 521 nm. The sensitivity of the instrument was determined by calibration. IO (between 10 and 150 pptV) was generated following the 184.9 nm photolysis of N₂O/CF₃I/N₂ mixtures with O₃ actinometry used to determine the photolysis flux. The detection limit was determined to be 0.3 pptV for a 300 s integration period, with an uncertainty of 23% (1σ). The instrument was deployed in August/September 2006 during the RHaMBLe (Reactive Halogens in the Marine Boundary Layer) campaign in Roscoff, France. Located on a small jetty, a few metres from the water’s edge at high tide, the instrument measured significant levels of IO on 11 days, with a maximum of 27.6 ± 3.2 pptV observed on one day (averaged over 10 s) representing the highest IO mixing ratio recorded in the marine boundary layer to date. IO displayed a clear diurnal profile with a maximum at low tide during the daytime. These results represent the first point measurements of IO in the atmosphere by LIF.  相似文献