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Panet I.,CNRS Paris Institute of Global Physics | Kuroishi Y.,Geographical Survey Institute | Holschneider M.,University of Potsdam
International Association of Geodesy Symposia | Year: 2012

For geodetic and geophysical purposes, such as geoid determination or the study of the Earth's structure, heterogeneous gravity datasets of various origins need to be combined over an area of interest, in order to derive a local gravity model at the highest possible resolution. The quality of the obtained gravity model strongly depends on the use of appropriate noise models for the different datasets in the combination process. In addition to random errors, those datasets are indeed often affected by systematic biases and correlated errors. Here we show how wavelets can be used to realize such combination in a flexible and economic way, and how the use of domain decomposition approaches allows to recalibrate the noise models in different wavebands and for different areas. We represent the gravity potential as a linear combination of Poisson multipole wavelets (Holschneider et al. 2003). We compute the wavelet model of the gravity field by regularized least-squares adjustment of the datasets. To solve the normal system, we apply the Schwarz iterative algorithms, based on a domain decomposition of the models space. Hierarchical scale subdomains are defined as subsets of wavelets at different scales, and for each scale, block subdomains are defined based on spatial splittings of the area. In the computation process, the data weights can be refined for each subdomain, allowing to take into account the effect of correlated noises in a simple way. Similarly, the weight of the regularization can be recalibrated for each subdomain, introducing non-stationarity in the a priori assumption of smoothness of the gravity field. We show and discuss examples of application of this method for regional gravity field modelling over a test area in Japan. © Springer-Verlag Berlin Heidelberg 2012. Source


Sobue S.-I.,Japan Aerospace Exploration Agency | Araki H.,National Astronomical Observation of Japan | Tazawa S.,National Astronomical Observation of Japan | Noda H.,National Astronomical Observation of Japan | And 3 more authors.
Advanced Techniques in Computing Sciences and Software Engineering | Year: 2010

This paper describes an application of a geographical information system with visualized and sonification lunar remote sensing data provided by Japan's lunar explorer (SELENE "KAGUYA"). Web based GIS is a very powerful tool which lunar scientists can use to visualize and access remote sensing data with other geospatial information. We discuss enhancement of the pseudo-colored visual map presentation of lunar topographical altimetry data derived from LALT and the map of the data to several sound parameters (Interval, harmony, and tempo). This paper describes an overview of this GIS with a sonification system, called "Moonbell". © Springer Science+Business Media B.V. 2010. Source


Heggy E.,Jet Propulsion Laboratory | Sedze M.,CNRS Paris Institute of Global Physics | Sedze M.,Institute Geographique National | Bretar F.,Institute Geographique National | And 4 more authors.
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2010

Until recently the coarse resolution of topographic mapping acted as a break on understanding the forces and processes that shape the Earth's surface. However, active surface deformation is an important indicator for the earth crustal dynamics since it is directly linked to earthquakes, volcanic eruptions and landslides. Both airborne laser scanning systems (LiDAR) and spaceborne interferometric synthetic aperture radars (InSAR) have provided valuable information for many case studies requiring high-resolution characterization of ground movement in relatively large areas to assess the threat and impact of natural hazards especially for volcanic eruptions. © 2010 IEEE. Source


Tateishi R.,Chiba University | Uriyangqai B.,Inner Mongolia Normal University | Al-Bilbisi H.,University of Jordan | Ghar M.A.,National Authority for Remote Sensing and Space science NARSS | And 9 more authors.
International Journal of Digital Earth | Year: 2011

Global land cover is one of the fundamental contents of Digital Earth. The Global Mapping project coordinated by the International Steering Committee for Global Mapping has produced a 1-km global land cover dataset - Global Land Cover by National Mapping Organizations. It has 20 land cover classes defined using the Land Cover Classification System. Of them, 14 classes were derived using supervised classification. The remaining six were classified independently: urban, tree open, mangrove, wetland, snow/ice, andwater. Primary source data of this land cover mapping were eight periods of 16-day composite 7-band 1-km MODIS data of 2003. Training data for supervised classification were collected using Landsat images, MODIS NDVI seasonal change patterns, Google Earth, Virtual Earth, existing regional maps, and expert's comments. The overall accuracy is 76.5% and the overall accuracy with the weight of the mapped area coverage is 81.2%. The data are available from the Global Mapping project website (http://www.iscgm.org/). TheMODISdata used, land cover training data, and a list of existing regional maps are also available from the CEReS website. This mapping attempt demonstrates that training/validation data accumulation from different mapping projects must be promoted to support future global land cover mapping. © 2011 Taylor & Francis. Source


Haas R.,Chalmers University of Technology | Sekido M.,Japan National Institute of Information and Communications Technology | Hobiger T.,Japan National Institute of Information and Communications Technology | Kondo T.,Japan National Institute of Information and Communications Technology | And 6 more authors.
Artificial Satellites | Year: 2010

We give a short overview about the achievements of the Fennoscandian- Japanese ultra-rapid dUT1-project that was initiated in early 2007. The combination of real-time data transfer, near real-time data conversion and correlation, together with near-real time data analysis allows to determine dUT1 with a very low latency of less than 5 minutes after the end of a VLBI-session. The accuracy of these ultra-rapid dUT1-results is on the same order than the results of the standard rapid-service of the International Earth Rotation and Reference Frame Service (IERS). The ultra-rapid approach is currently extended to 24 hour sessions and is expected to become an important contribution for the future next generation VLBI system called VLBI2010. Source

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