Surthce elevation is tile basic data for geo-science. It is difficult to retrieve tidal-flats＇ elevation from a single Re- mote Sensing （RS） image because of the complicated sediment dynanical environment and huge ...Surthce elevation is tile basic data for geo-science. It is difficult to retrieve tidal-flats＇ elevation from a single Re- mote Sensing （RS） image because of the complicated sediment dynanical environment and huge spatial difference in tidal-flats＇ moisture content. A Digital Elevation Model （DEM） construction method for inconstant inter-tidal zone based on high tempo-resolution MODIS data set in a short period is proposed in a ease study on the Dongsha Sandbank of the Jiangsu Radial Tidal Sand-ridges. In the present study, a batch-preprocessing method based on image partition to handle massive MODIS IB images is developed and applied to 8163 scenes of MODIS images. The dataset of short-period and muhi-temporal MODIS images for inter-tidal flats＇ DEM inversion is selected and the usability of MODIS dataset is analyzed. Shorelines of the Dongsha Sandbank are extracted by use of batch supervised classification. In accord with tidal- 0 level forecasted by the Chenjiawu Tidal Gauge Station at the overpass moment of each RS image, DEMs of inter-tidal flats in January and sutmner（Jul, Aug and Sept）, 2003 are built under ArcG1S9.2. Studies show that： （1） The dataset of short-duration and muhi-phase MODIS images can be used to retrieve the historical DEM of tidal-flats at changeful tidal flats. （2） Aualysis on usability of MODIS images from Aqua and Terra indicates that there are more usable and higbquality MODIS images in spring, autumn and winter, but less in summer. Therefore, the period for building inter-tidal fiats＇ DEM is suggested to be one month in spring, autumn and winter and three months in summer.展开更多
The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow ...The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow Sea seafloor. The anticlockwise rotary tidal wave to the south of Shandong Peninsula meets the following progressive tidal wave from the South Yellow Sea, forming a radial current field outside Jianggang. This current field provides a necessary dynamic condition for the formation and existence of the radial sand ridges on the Yellow Sea seafloor. The results of simulated 'old current field (holocene)' show that there existed a convergent-divergent tidal zone just outside the palaeo-Yangtze River estuary where a palaeo-underwater accumulation was developed. The calculated results from wave models indicate that the wave impact on the topography, under the condition of high water level and strong winds, is significant. The storm current induced by typhoons landing in the Yangtze River estuary and turning away to the sea can have an obvious influence, too, on the sand ridges. The depositional dynamic mechanism of formation andevolution of the radial sand ridges on the Yellow Sea seafloor is ' tidal current-induced formation-storm-inducedchange-tidal current-induced recovery' .展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos .40701117 andJ0630535)
文摘Surthce elevation is tile basic data for geo-science. It is difficult to retrieve tidal-flats＇ elevation from a single Re- mote Sensing （RS） image because of the complicated sediment dynanical environment and huge spatial difference in tidal-flats＇ moisture content. A Digital Elevation Model （DEM） construction method for inconstant inter-tidal zone based on high tempo-resolution MODIS data set in a short period is proposed in a ease study on the Dongsha Sandbank of the Jiangsu Radial Tidal Sand-ridges. In the present study, a batch-preprocessing method based on image partition to handle massive MODIS IB images is developed and applied to 8163 scenes of MODIS images. The dataset of short-period and muhi-temporal MODIS images for inter-tidal flats＇ DEM inversion is selected and the usability of MODIS dataset is analyzed. Shorelines of the Dongsha Sandbank are extracted by use of batch supervised classification. In accord with tidal- 0 level forecasted by the Chenjiawu Tidal Gauge Station at the overpass moment of each RS image, DEMs of inter-tidal flats in January and sutmner（Jul, Aug and Sept）, 2003 are built under ArcG1S9.2. Studies show that： （1） The dataset of short-duration and muhi-phase MODIS images can be used to retrieve the historical DEM of tidal-flats at changeful tidal flats. （2） Aualysis on usability of MODIS images from Aqua and Terra indicates that there are more usable and higbquality MODIS images in spring, autumn and winter, but less in summer. Therefore, the period for building inter-tidal fiats＇ DEM is suggested to be one month in spring, autumn and winter and three months in summer.
基金Project supported by the National Natural Science Foundation of China (Grant No. 49236120).
文摘The results of simulated tidal current field, wave field and storm-induced current field are employed to interpret the depositional dynamic mechanism of formation and evolution of the radial sand ridges on the Yellow Sea seafloor. The anticlockwise rotary tidal wave to the south of Shandong Peninsula meets the following progressive tidal wave from the South Yellow Sea, forming a radial current field outside Jianggang. This current field provides a necessary dynamic condition for the formation and existence of the radial sand ridges on the Yellow Sea seafloor. The results of simulated 'old current field (holocene)' show that there existed a convergent-divergent tidal zone just outside the palaeo-Yangtze River estuary where a palaeo-underwater accumulation was developed. The calculated results from wave models indicate that the wave impact on the topography, under the condition of high water level and strong winds, is significant. The storm current induced by typhoons landing in the Yangtze River estuary and turning away to the sea can have an obvious influence, too, on the sand ridges. The depositional dynamic mechanism of formation andevolution of the radial sand ridges on the Yellow Sea seafloor is ' tidal current-induced formation-storm-inducedchange-tidal current-induced recovery' .
