Land surface temperature (LST) is a key parameter in numerous environmental studies. However, currently, there is no satellite sensor that can completely provide LST data with both high spatial and high temporal resolutions simultaneously. LST downscaling is regarded as an effective remedy for improving the temporal and spatial resolutions of LST data. In this study, a geographically and temporally weighted autoregressive (GTWAR) model of LST downscaling is that comprehensively considers the spatial heterogeneity, spatial autoregression and temporality of LST is newly proposed. The normalized difference water index (NDWI), the normalized difference built-up index (NDBI), and the normalized difference vegetation index (NDVI) were selected as explanatory variables to downscale the moderate resolution imaging spectroradiometer (MODIS) LST from 1000 m to 100 m, while the Landsat 8 LST was selected as the reference data. Compared with the thermal data sharpening (TsHARP), the geographically weighted regression (GWR), the geographically weighted autoregressive (GWAR) and the geographically and temporally weighted regression (GTWR) downscaling methods, the proposed method was superior based on quantitative indices, with the lowest root mean square error (RMSE) (Zhangye: 1.57 ℃, Beijing: 1.22 ℃) and mean absolute error (MAE) (Zhangye: 1.06 ℃, Beijing: 0.85 ℃). The downscaling model of GTWAR will facilitate improvements in the accuracy of downscaling for temporal series of LST data. Index Terms-Geographically and temporally weighted autoregressive (GTWAR) model, land surface temperature (LST), spatial downscaling, Landsat 8, moderate resolution imaging spectroradiometer(MODIS).
With the increasing of data volume and data dimensions in road network query, the response gets slow in searching services, which cannot satisfy users demand for preference-based searching. This paper proposes a user preference-based Skyline query algorithm. At the first stage, this method is based on the fact that the static property of data does not change during the query processes. Therefore, Skyline starts its calculation in the non-spatial data set to have the candidate results and dominance relation. Then it calculates the total costs of routine by defining user preference function. At the second stage, compare the data connections with the total costs of preference to minimize time for processing data and searching. The experiment result shows that the definition of user preference meets the users demand, and Skyline query algorithm benefits to have quick response.
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