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Abstract:
Global climate change is one of the significant challenges of our time. A deeper understanding of how greenhouse gases (GHGs) impact and respond to climate change is one of the urgent scientific questions in Earth system science. Therefore, expanding the observational foundation for climate change studies with accurate, long-term, and consistent benchmark data is a fundamental need of climate science. The mission CACES—Climate and Atmospheric Components Exploring Satellites—based on the occultation technique with Low Earth Orbit (LEO) satellites to monitor the atmospheric thermodynamic state variables (i.e., pressure, temperature, and humidity) and greenhouse gases (i.e., H2O, CO2, CH4, etc.), was proposed in China. It has been accepted by the Strategic Priority Research Program of the Chinese Academy of Sciences (SPRPCAS) as the phase of breakthroughs in essential detection techniques since 2020. The mission architecture, including the constellation's design, the proposed payloads, and the spacecraft, were studied. CACES combines the LEO-LEO microwave occultation (LMO), infrared-laser occultation (LIO), and Nadir Hyperspectral Imaging (NHI) techniques aiming to provide essential atmospheric datasets for the research of global climate change. Through the end-to-end simulation, the spatiotemporal distribution of measurements was analyzed and evaluated for ensuring the desired performance. And the retrieval methods with bending angle and transmission amplitude from microwave and infrared-laser signals were also studied.
