Comparing GRACE-FO KBR and LRI Ranging Data with Focus on Carrier Frequency Variations

The GRACE Follow-On satellite mission measures distance variations between its two satellites in order to derive monthly gravity field maps, indicating mass variability on Earth a scale of few 100 km originating from hydrology, seismology, climatology and other sources. This hosts ranging instruments, conventional microwave system based K(a)-band (KBR) novel laser instrument (LRI), both relying interferometric phase readout. In this paper, we show how the measurements can be converted into range data using time-dependent carrier frequency (or wavelength) that takes account potential intraday or frequency. Moreover, analyze KBR-LRI residuals discuss which error noise contributors limit at high low Fourier frequencies. It turns out agreement KBR LRI biased observations slightly improved by considering processing. Although effect is probably small enough have little relevance for determination current precision level, analysis detailed characterization potentially future more precise missions.