Simulations of Laser Ranging Instrument Data in Future Gravity Missions

Since 2002, GRACE and GRACE-FO have recorded valuable data on changes in the Earth mass distribution, indicating melting ice caps, a rising sea level and redistributions of groundwater. The continuation of this data collection is of high interest for climate research. Future gravity missions, such as NGGM, GRACE-C and TianQin-2 are currently under development and will use a Laser Ranging Instrument (LRI) to measure the main observable – distance variations between two satellites which are orbiting the Earth in a separation of 200 km.To support studies for future gravity missions, we developed a novel LRI Level 1A data simulator that uses orbit files containing the satellite positions and velocities, as well as attitude datasets providing satellite orientations. Under consideration of physical principles and instrument characteristics of laser interferometers in space, the simulator derives LRI phase measurements and LRI inter-satellite pointing angles in a format similar to GRACE-FO level1a files. The data is further processed to level1b using the same software used for the processing of GRACE-FO LRI flight data. The simulator is already capable of deriving realistic LRI ranging data and led to improvements in our GRACE-FO LRI level1b processing chain.In this poster presentation we provide an overview of which effects are already considered in the simulator, explain the data validation strategy, and present a tone-error analyses from  different contributors.