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2002年3月成功发射的美德合作卫星重力计划GRACE(Gravity Recovery And ClimateExperiment),即将提供空间分辨率约为200 km而时间分辨率为1个月的时变地球重力场模型序列。GRACE计划的星座由两颗相距约220 km,高度保持为300-500 km、倾角保持约90°的近极轨卫星组成。由于采用星载GPS和非保守力加速度计等高精度定轨技术,以及高精度的星一星跟踪数据反演地球重力场,在几百公里和更大空间尺度上, GRACE重力场的精度大大超过此前的卫星重力计划。根据GRACE时变重力场反演的地球系统质量重新分布,将对固体地球物理、海洋物理、气候学以及大地测量等应用有重要的意义。虽然其设计寿命只有5 yr,但研究表明GRACE的结果可用于研究北极冰长期时间尺度的变化,并进而研究极冰融化对全球气候变化,特别是对海平面长期变化的影响。在季节性时间尺度上,利用GRACE重力场反演的质量重新分布足以揭示平均小于1 cm的地表水变化,或小于1 mbar。的海底压强变化。除了巨大的社会效益和经济效益外,这些变化对了解地球系统的物质循环(主要是水循环)和能量循环有非常重要的意义。介绍GRACE重力场揭示的地球系统质量重新分布,为理解其地球物理应用提供必需的准备;同时针对我国大陆和沿海地区的地球物理应用提出初步的设想。
The GRACE (Gravity Recovery And Climate Experiment) successfully launched in March 2002 is about to provide a time-varying geo-gravitational field model sequence with a spatial resolution of about 200 km and a temporal resolution of one month. The constellation of the GRACE plan consists of two near-polar orbiting satellites at a distance of about 220 km, a height of 300-500 km and an inclination of about 90 °. Due to the high accuracy orbit determination technology such as on-board GPS and non-conservative accelerometers, and high-precision satellite-star tracking data for the retrieval of Earth’s gravitational field, the accuracy of the GRACE gravitational field is much greater over hundreds of kilometers and beyond More than the previous satellite gravity plan. The redistribution of the quality of the Earth’s system retrieved from the GRACE time-varying gravitational field will be of great importance to the applications of solid geophysics, oceanography, climatology and geodesy. Although its design life is only 5 yr, studies have shown that GRACE’s results can be used to study long-term time scales of Arctic ice and to study the effects of polar ice melting on global climate change, especially on long-term changes in sea level. On a seasonal time scale, mass redistribution using GRACE gravity field inversion is sufficient to reveal surface water changes less than 1 cm in average, or less than 1 mbar. The sea floor pressure changes. In addition to great social and economic benefits, these changes are very important for understanding the material cycle (mainly the water cycle) and the energy cycle of the Earth system. This paper introduces the redistribution of the mass of the Earth system revealed by the GRACE gravitational field and provides the necessary preparation for understanding its geophysical applications. At the same time, it proposes some preliminary ideas for the geophysical applications in China’s mainland and its coastal areas.