排序方式: 共有12条查询结果,搜索用时 46 毫秒
11.
Xu Yidi Yu Le Peng Dailiang Zhao Jiyao Cheng Yuqi Liu Xiaoxuan Li Wei Meng Ran Xu Xinliang Gong Peng 《中国科学:地球科学(英文版)》2020,63(9):1390-1407
Annual land use land cover(LULC) change information at medium spatial resolution(i.e. at 30 m) is required in numerous subjects, such as biophysical modelling, land management and global change studies. Annual LULC information,however, is usually not available at continental or national scale due to reasons such as insufficient remote sensing data coverage or lack of computational capabilities. Here we integrate high temporal resolution and coarse spatial resolution satellite images(i.e., Moderate Resolution Imaging Spectroradiometer(MODIS) and Global Inventory Modelling and Mapping Studies(GIMMS) normalized difference vegetation index(NDVI)) with high spatial resolution datasets(China's Land-Use/cover Datasets(CLUDs) derived from 30-meter Landsat TM/ETM+/OLI) to generate reliable annual nominal 30 m LULC maps for the whole of China between 1980 and 2015. We also test the performance of a statistical based change detection algorithm(Breaks for Additive Seasonal and Trend), originally designed for tracking forest change, in classifying all-type LULC change.As a result, a nominal 30 m annual land use/land cover datasets(CLUD-A) from 1980 to 2015 was developed for the whole China. The mapping results were assessed with a change sample dataset, a regional annual validation sample set and a three-year China sample set. Of the detected change years, 75.61% matched the exact time of conversion within ±1 year. Annual mapping results provided a detail process of urbanization, deforestation, afforestation, water and cropland dynamics over the past 36 years. The consistent characterization of land change dynamics for China can be further used in scientific research and to support land management for policy-makers. 相似文献
12.
Late Quaternary loess deposition in the southern Chaiwopu Basin of the northern Chinese Tian Shan foreland and its palaeoclimatic implications
下载免费PDF全文
![点击此处可从《Boreas: An International Journal of Quaternary Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Honghua Lu Yidi Xu Ying Niu Zhen Wang Hui Wang Junxiang Zhao Weiguo Zhang Xiangmin Zheng 《Boreas: An International Journal of Quaternary Research》2016,45(2):304-321
The piedmont aeolian sediment in Central Asia is has been widely used for Quaternary palaeoclimatic reconstructions. Here we present detailed sedimentological and rock magnetic investigations on 188 samples from the ~9.4‐m‐thick Urumqi River section (URS) in the southern Chaiwopu Basin of the northern Chinese Tian Shan foreland. Optically stimulated luminescence (OSL) dating constrains the time‐span of the URS loess sedimentation from c. 28 to c. 6.8 ka. This chronology implies that the onset of the URS loess sedimentation is approximately synchronous with the Shangwangfeng Glaciation (MIS 2) in the headwaters of the Urumqi River. Analyses of sediment grain size and rock magnetic parameters indicate that sediment grain‐size composition controls magnetic properties of the URS loess, i.e. the wind intensity model, distinct from the pedogenic model interpreting the variations in magnetic properties of the loess in the Chinese Loess Plateau (CLP). Overall, the variations in sediment grain size and magnetic properties throughout the URS indicate that the present study area was dominated by a climate of strengthened wind associated with gradually intensified aridity during the latest Pleistocene. In contrast, the intensity of aridity and coldness during the early Holocene gradually became relatively weakened. 相似文献