TY - JOUR

T1 - Comparing GRACE-FO KBR and LRI Ranging Data with Focus on Carrier Frequency Variations

AU - Müller, Vitali

AU - Hauk, Markus

AU - Misfeldt, Malte

AU - Müller, Laura

AU - Wegener, Henry

AU - Yan, Yihao

AU - Heinzel, Gerhard

N1 - Funding information: This work and some authors have been supported by: The Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, Project-ID 434617780, SFB 1464). Clusters of Excellence “QuantumFrontiers: Light and Matter at the Quantum Frontier: Foundations and Applications in Metrology” (EXC-2123, project number: 390837967); the European Space Agency in the framework of Next Generation Gravity Mission development and ESA’s third-party mission support for GRACE-FO; the Chinese Academy of Sciences (CAS) and the Max Planck Society (MPG) in the framework of the LEGACY cooperation on low-frequency gravitational-wave astronomy (M.IF.A.QOP18098) and Bundesministerium für Bildung und Forschung (BMBF, project number: 03F0654B).

PY - 2022/9/1

Y1 - 2022/9/1

N2 - 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 on a scale of a few 100 km originating from hydrology, seismology, climatology and other sources. This mission hosts two ranging instruments, a conventional microwave system based on K(a)-band ranging (KBR) and a novel laser ranging instrument (LRI), both relying on interferometric phase readout. In this paper, we show how the phase measurements can be converted into range data using a time-dependent carrier frequency (or wavelength) that takes into account potential intraday variability in the microwave or laser frequency. Moreover, we analyze the KBR-LRI residuals and discuss which error and noise contributors limit the residuals at high and low Fourier frequencies. It turns out that the agreement between KBR and LRI biased range observations can be slightly improved by considering intraday carrier frequency variations in the processing. Although the effect is probably small enough to have little relevance for gravity field determination at the current precision level, this analysis is of relevance for detailed instrument characterization and potentially for future more precise missions.

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

KW - GRACE Follow-On

KW - instrumentation

KW - laser ranging

KW - microwave ranging

UR - http://www.scopus.com/inward/record.url?scp=85139566821&partnerID=8YFLogxK

U2 - 10.3390/rs14174335

DO - 10.3390/rs14174335

M3 - Article

VL - 14

SP - 4335

JO - Remote sensing

JF - Remote sensing

SN - 2072-4292

IS - 17

M1 - 4335

ER -