Research on gravity measurement reference stations based on quantum absolute gravimeter

Absolute gravity measurement based on laser interferometry is the main means to establish gravity measurement reference, and it is also the gravity reference instrument used currently. In recent years, with the development of quantum absolute gravity measurement techniques, new opportunities have been presented for establishing a gravity reference with higher accuracy. With the support of the National Development and Reform Commission, Huazhong University of Science and Technology established the “precision gravity measurement facility (PGMF)” as a major national scientific and technological infrastructure. A key component of this facility's construction is the establishment of a micro-Gal level absolute gravity measurement reference station. This station provides a standardized reference for gravity measurement instruments and data, serving as a foundation for achieving high-precision measurements and applications in the field of gravity measurement. This paper is intended to establish a gravity measurement reference station centered on a high-precision quantum absolute gravimeter.

This paper focused on the construction of a micro-Gal level gravity reference station. The establishment of a high-precision, multi-point gravity comparison field was investigated, with emphasis on the overall environmental conditions of the comparison sites, as well as the gravity distribution and vertical gravity gradient at these points. The development of high-precision quantum absolute gravimeters was described, with particular attention given to two types of quantum absolute gravimeters that support the establishment and application of the micro-Gal level gravity reference station. A background physical field monitoring system was developed, comprising a superconducting gravimeter for monitoring background gravity variations within the comparison field, along with barometric pressure and groundwater data for environmental monitoring in the vicinity of the comparison field. Through high-precision gravity measurements of the comparison field and real-time, high-precision monitoring of the background environment, a micro-Gal level gravity comparison field was ultimately established.

A high-precision quantum absolute gravimeter has been successfully developed. This includes a reference-type quantum absolute gravimeter (model AG-ref), which is suitable for long-term continuous absolute gravity measurements in laboratories and observatories, achieving an accuracy of 2 μGal. Additionally, a miniaturized quantum absolute gravimeter (model RAI-g) has been developed for fixed-point calibration at stations, capable of providing comparison and measurement services for relevant industrial sectors, with an accuracy ranging from 2 to 5 μGal. Based on this instrumentation, a high-precision gravity comparison field and a comprehensive background physical field monitoring system have been established. By utilizing the self-developed high-precision quantum absolute gravimeter for comparison and calibration, a gravity reference station with an accuracy of 2 μGal has been ultimately established. Furthermore, long-term monitoring of background gravity variations is conducted using high-precision superconducting gravimeters and quantum absolute gravimeters, enabling continuous monitoring and maintenance of the gravity values at the reference points. At present, this platform possesses the capability to ensure traceability for high-precision gravity measurement benchmarks, as well as to perform inspection, comparison, and calibration of various gravity measurement instruments.

A reference quantum absolute gravimeter suitable for station measurements and a miniaturized quantum absolute gravimeter for reference extension were developed. A gravity comparison field and a background physical environment monitoring system were established, and finally a micro-Gal level gravity measurement reference station was established.