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| 1 | China Digital Ocean Prototype System显示文摘Digital Ocean is a new research domain of Digital Earth.Because of the spatiotemporal,three-dimensional(3D)and intrinsically dynamic nature of ocean data,it is more difficult to make a breakthrough in this domain.The construction of the China Digital Ocean Prototype System(CDOPS)pushes Digital Ocean a step forward from its operation as a mere concept to its achievement as a realistic system.In this paper,the technical framework of the CDOPS is discussed,including its data,function,and application layers.Then,two key technologies are studied in detail that will enable the construction of the 3D ocean environment and the visualization of the ocean model output data.Practical demonstrations show that the CDOPS provides a technical reference for the development of Digital Ocean.This paper is based on an ongoing research project of the development of CDOPS that aims at the facilitation,integration,sharing,accessing,visualization,and use of the ocean data and model computing data from the Digital Earth perspective. | Xin Zhang Wen Dong Sihai Li Jiancheng Luo Tianhe Chi | 2011 | International Journal of Digital Earth2011,4,3: | 7 |
| 2 | Effects of polarization calibration on aerosol optical depth retrieval: An ocean case sensitivity analysis显示文摘Reflectance measurements of both the visible and infrared bands of passive remote sensing sensors are widely used to retrieve aerosol optical depth(AOD) information. This is performed commonly for data obtained over both ocean and land, and these measurements allow for the off line development of a lookup table using radiative transfer models. Owing to molecular and aerosol effects, the reflected light received by the sensor is usually highly polarized. The linear polarization effect may be up to 100%, and the polarization factor of a sensor optical system will change the total intensity as well as the polarization status of the signal reaching the detector. The detector response will be different when the incident light polarization status changes, even if the total intensity remains constant. However, if the polarization calibration is neglected, it will cause obvious errors in the aerosol data retrieval. This is especially true for aerosol optical depth retrieval over an ocean. This measurement relies directly on the reflectance output of the sensor. Cases involving land surfaces are not discussed herein because the inhomogeneous properties conceal the error due to polarization. Taking the 550 and 860 nm bands as examples, the difference between the real top-of-atmosphere(TOA) reflectance and the reflectance reaching the detector is calculated using three different sensor polarization standards according to the Sea-viewing Wide Field-of-view Sensor(Sea Wi FS) and Moderate Resolution Imaging Spectroradiometer(MODIS) standards. The differences in AOD retrieval are also demonstrated using the lookup table developed previously from a vector radiative transfer code. The results reveal that under a normal situation in which the AOD is 0.15, the maximum AOD retrieval error could reach 0.04 in 550 nm but only 0.02 in 860 nm for the dust aerosol model. For the soot aerosol model, the maximum AOD retrieval error is 0.1 in 550 nm and 0.12 in 860 nm, indicating that the lack of polarization calibration will lead to large errors in aerosol retrieval over an ocean. | LIU TianYue CHI TianHe CHEN Wei | 2015 | Science China Earth Sciences2015,58,6: | 1 |
| 3 | Using virtual forest environment on collaborative forest management显示文摘 | Mingyao Qi Tianhe Chi Xin Zhang | 2004 | Geoscience and Remote Sensing Symposium2004,7,7: | 1 |
| 4 | “Digital earth” in support of an online oceanic educational public service and popularization显示文摘According to the initial vision of 'digital earth' (DE), the public should constitute a significant proportion of its users. However, to date, most of the studies and applications have focused on science, the private sector and government. A DE-supported online oceanic educational public service and popularization system, iOcean, is studied. First, the vision for the public's engagement with 'digital ocean' is described: an analysis is presented from four aspects, i.e., the space dimension, the time dimension, the state dimension and its relationship with human beings. Second, the technical framework of iOcean is discussed, including data updating and model computing, the data, the function, and the application layers. Third, two key technologies are studied in detail that will enable the construction of iOcean. More than half a million public viewers have used the current version's website. Practical demonstrations show that iOcean can bring virtual oceans to web browsers and desktops and construct a bridge between government departments and the general public. | ZHANG Xin DONG Wen JIANG Xiaoyi SHI Suixiang CHI Tianhe | 2013 | Acta Oceanologica Sinica2013,32,5: | 0 |