Progress of Earth Observation and Earth Science in China
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SPACE SCIENCE ACTIVITIES IN CHINA Progress of Earth Observation and Earth Science in China GUO Huadong1,2, LIU Guang1, LIANG Dong1,2, ZHANG Lu1, XIAO Han1 National Report 2016 1 (Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, Beijing 100094) 2 (University of Chinese Academy of Sciences, Beijing 100049) Abstract Sustainability is the current theme of global development, and for China it is not only an opportunity but also a challenge. In 2016, the Paris Agreement on climate change was adopted, addressing the need to limit the rise of 2018 global temperatures. The United Nations (UN) has set Sustainable Development Goals (SDGs) to transform our world in terms of closely linking human well-being, economic prosperity and healthy environments. Sustainable development requires the support of spatial information and objective evaluation, and the capability of macro- scopic, rapid, accurate Earth observation techniques plays an important role in sustainable development. Recently, Earth observation technologies have been developing rapidly in China, where scientists are building coordinated, comprehensive and sustainable Earth observation systems for global monitoring programs. Recent efforts include the Digital Belt and Road Program (DBAR) and comparative studies of the “three poles”. This and other re- E-mail: [email protected] searches will provide powerful support for solving problems such as global change and environmental degradation. Key words Earth observation, Earth system science, Big Earth Data, Moon-based Earth observation, Global sustainable de- velopment, Digital Belt and Road Program, Three poles Earth is our common homeland. However, global 1. Advances in Earth Observation change, disasters, and environmental problems are af- fecting the safety and development of every country. Sustainable Development Goals (SDGs) underscore the China has actively responded to and participated in the need for the scientific community and emphasize global UN SDGs, the Paris Climate Change Agreement and the issues such as climate change, renewable energy, food, Charter on Cooperation to Achieve the Coordinated Use health and water supply[1]. They also show the impor- of Space Facilities in the Event of Natural or Techno- tance of coordinating research on every factor affecting logical Disasters, and is cooperating with other coun- those issues, such as society, the economy, and the en- tries to jointly achieve sustainable development of the vironment, using global monitoring and simulation. In planet. Earth observation technologies in China are de- November 2017, the 23rd Conference of the Parties to veloping rapidly. At present, Earth observation systems the United Nations (UN) Framework Convention on are being built to coordinate comprehensive research on Climate Change was held in Bonn, Germany, to formu- sustainability. Major global monitoring programs in- late guidelines for the implementation of the Paris clude the DBAR and “three-pole” comparative studies Agreement. The main issues are controlling the global of the North Pole, South Pole, and the “High-mountain temperature within 2 degrees Celsius of that before the Asia” region around the Himalayas and Qinghai-Tibetan industrial revolution, and reducing greenhouse gas Plateau. The data produced can provide powerful sup- emissions in stages. In order to guide actions, it is nec- port for solving problems such as global change and essary to determine the allocation and interdependence environmental degradation. of the indicators at local, national, and global scales. SPACE SCIENCE ACTIVITIES IN CHINA Products and standards need to be established for moni- Regarding sensors and the observation strategy, the toring, evaluating, and understanding the relationships derivation of Doppler parameters with the removal of among the indicators[2]. In order to achieve this goal, the stop-and-go assumption have been completed and a China has further strengthened the construction of ob- Moon-based SAR signal model based on curve trajec- servation facilities and improved international scientific tory has been established. Following this, a 2D spectrum programs to expand its capabilities for comprehensive of the Moon-based SAR was derived by utilizing the observation to meet the goals of sustainable develop- series reversion method. Based on the Earth-Moon National Report 2016 ment. It has also strengthened the standards for Earth geometric relationship and relative velocity of the radar, science data, the design of processing methods, and the observation geometry of a single base station’s radar mechanisms to ensure global information sharing[3]. has been established. By means of calculating the solar zenith angle between a specific point’s normal vector 1.1 Moon-based Earth Observation and the solar direction vector, an instantaneous observa- The Moon is the only natural satellite of Earth, and it tional scope variation and the theoretical value of the can be utilized as a long-term, stable Earth observation long wave and shortwave radiation can be derived. platform. Compared to manmade satellite platforms, ob- Chinese scientists also proposed to carry out research on 2018 serving geoscience phenomena from the Moon has the observing Earth radiation’s from the Moon. Using an advantages of longevity, consistency, and stability. Eq- active cavity radiometer with a total channel (0.2 to uipping various kinds of sensors on the lunar surface 100 μm), a solar channel (0.2 to 4 μm), and near-infrared will provide an unprecedented guarantee of comprehen- channel (0.7 to 1.1 μm) was proposed for the total out- sive multi-sphere studies at the global scale, and give going Earth radiation, the reflected solar radiation, and solutions to a series of key scientific issues on the inter- near-infrared thermal emission. action between multiple spheres from the perspective of In research on the lunar environment and observation a geodynamic system. This can enhance the ability to site selection, simultaneous observations and a consis- observe geoscience phenomena and help deepen our tency test were completed for the same occultation event understanding of the Earth system. In response to Earth from deep-space bistatic stations. The preliminary test system science and the development of and demand for revealed strong correlation between the fluctuation of the global change research, Chinese scientists proposed a lunar ionosphere and time variance of solar zenith angles. Moon-based Earth observation platform for long-term Taking into consideration the influence of the nodal pre- systematic observation. It will be the first systematic re- cession of the ecliptic and the Moon’s path, the illumi- search about the principle and feasibility of a Moon- nation conditions of the two poles of the Moon at differ- based platform[4]. ent periods were further studied. For the first time, the ill- Research on a Moon-based Earth observation plat- umination results of half of the lunar precession period form has produced a simulation system for Moon-based were given. A comprehensive analysis of the lunar South Earth observation geometry and a model based on the Pole was carried out along with an analysis of the special geometrical relationship between the Sun, Moon, and geological conditions of the South Pole-Aitken basin. Earth. After analyzing the spatial coverage, the temporal Based on national strategic needs, China’s Chang’E coverage, and the look vector pointing error, it has been IV mission of scientific exploration targets needs from found that equipping sensors in the full observation re- three aspects: material composition, shallow structure, gion of the lunar surface (80°S–80°N, 80°W–80°E) will and the Moon’s low-frequency radio environment. Moon- have optimal performance for spatial, temporal, and an- based Earth observation is a new research field, but is gular coverage of a given Earth surface feature. Further- an inevitable trend after air-borne and space-borne plat- more, based on the polar coordinate representation of forms developed to a certain stage. This will give a new, nadir points, a new automatic geometric correction me- unique solution to a series of key scientific issues about thod has been proposed for cross-platform Moon- based the Earth system. Earth observation images. This achievement solves the 1.2 Big Earth Data Science Engineering distortion caused by the cyclic movements of the nadir point, Earth curvature, and elevation, and it also main- The Chinese Academy of Sciences (CAS) has been fully tains the integrity and authenticity of the image[4, 5]. aware of the importance of Big Earth Data and launched ·290· GUO Huadong, et al. Progress of Earth Observation and Earth Science in China a project titled “Big Earth Data Science Engineering world-class Big Earth Data platform to drive the disci- (CASEarth)” in the Strategic Priority Research Program pline. CASEarth will explore the new big data-driven, (SPRP) of CAS, in order to carry out systimatic research multidisciplinary, globally collaborative paradigm of on Big Earth Data. SPRP is a major scientific and tech- scientific discovery, and demonstrate and propel major nological task approved by the Chinese government to breakthroughs in Earth system sciences, life sciences be deployed, organized, and implemented by CAS. It is and the associated disciplines. (3) Construct a decision National Report 2016 oriented toward resolving major scientific and techno- support system. The system should serve high-level logical