New Versions of the AEI-derived LRI1B dataset
Laura MüllerVitali MüllerMalte MisfeldtHenry WegenerYihao YanMarkus HaukPallavi BekalSimon BähreGerhard Heinzel
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Abstract:
<p>The inter-satellite distance changes of the GRACE Follow-On spacecraft are measured by the main science instrument, the K-Band Ranging (KBR) system, and by the new Laser Ranging Interferometer (LRI), which exhibits a higher precision. The official ranging data is provided by the Science Data System (SDS) in the so-called KBR1B and LRI1B data products, which are available in the latest version v04. However, the Albert Einstein Institute (AEI) in Hannover is deriving alternative LRI1B data products (v50+v52). These data sets allow us to investigate different processing strategies that might improve the quality of the ranging data.</p><p>We will present the most important processing steps for the AEI-derived data products and compare them to the official SDS v04 data. The main differences in the processing regard</p><ul><li>the deglitching algorithm, which is essential to remove disturbances induced by thruster activations or by single event upsets</li> <li>transformation of LRI time-tags to GPS time using a smooth and at day-bounds continuous correction formed by CLK1B, TIM1B, datation reports and empirical offsets obtained by daily cross-correlating KBR and LRI (only v50)</li> <li>conversion of phase-to-range using a novel formula that was published recently and that can utilize a time-depend laser frequency (scale factor)</li> <li>light-time-correction using alternative formulas that are expected to be more precise</li> <li>tilt-to-length (TTL) coupling correction, which is similar to the antenna offset correction (AOC) in KBR1B but missing in LRI1B v04 so far.</li> </ul><p>Furthermore, we have implemented a quality flag to indicate special events such as sun-blinding periods or momentum transfer events that might reduce the quality of the ranging data. This allows to down-weight affected segments during gravity field recovery. By comparing LRI1B v04 and AEI-derived LRI1B data, a verification and validation of the official dataset is possible. We will conclude with some examples where the LRI1B data quality can be improved compared to the v04 results.</p><p>Our LRI1B datasets are available at:&#160; https://www.aei.mpg.de/grace-fo-ranging-datasets</p>Keywords:
Ranging