Above-ground biomass of forest has great research and application value in the forest ecological system. There are mainly three types of models for estimating above-ground biomass of forest, i.e., forest measuring method, remote sensing method and integrated method. Remote sensing technique has become an important means for obtaining above-ground biomass of forest at the regional scale. There are mainly four types of remote sensing models, namely empirical, ANN, physical and NPP based models. This paper has analyzed and discussed the present methods for estimating above-ground biomass of forest based on remote sensing as well as their advantages and disadvantages. Finally, this paper points out that the integrated method combining remote sensing technique and forest succession model can be generally used to estimate above-ground biomass of forest at the regional scale in future.
Near surface air temperature is an important environment variable in many earth system models,because it is a key factor in the energy and water exchanges between land surface and atmosphere. Detailed measurements of spatial and temporal variations of near surface air temperature are critical for the effective understanding of climate, hydrology, ecology, agriculture and terrestrial life processes. Traditionally meteorological observation could provide accurate air temperature data at the point scale, but most earth system models need gridded input variables. Satellite remote sensing provides a straightforward and consistent way to observe air temperature at regional and global scales with more spatially detailed information than meteorological data. This paper systematically reviews the air temperature retrieving algorithms for thermal remote sensing data, which include TVX approaches, statistical approaches, neural network approaches and energy balance approaches. The main advantages and limitations of these four methods are also discussed. Finally, the development tendencies of estimating air temperature by remote sensing are pointed out, such as intensive research on thermal radiant transfer model, spatial-temporal scaling of air temperature and improvement of cloud detection.
This paper has dealt with some key problems existent in land cover mapping and analyzed objective adaptability of the classification system,which include the impacts of land cover definition uncertainty on classification effects, the features and adaptability of the classification algorithms, the gap and effects of fine and coarse scale monitoring techniques, the capability of land cover scaling for application, the scaling effects on classification, the procedures,problems and solutions of the classification system of land cover,the classification algorithm and its accuracy assessment, and the factors and solutions of accuracy and errors of the current monitoring systems.
In this paper, we propose a framework of GIS service chain for geodata and geoprocessing web services to handle complex geospatial tasks in web environment using XML web service, OGC standard and workflow techniques. An online image fusion web service is developed as an example based on the framework. This web service allows different images can be fused on-line. The prototype system integrated industry standards, including Web services, OGC WCS, OGC WPS, WSDL and BPEL4WS, allows invoke geoprocessing functionality in a platform and language independent manner on the Internet.