基于车载原子重力仪的外场绝对重力快速测绘研究

Research on rapid surveying and mapping of outfield absolute gravity based on vehicle-mounted atomic gravimeter

地球重力场信息是大地测量学、地球物理学、地球动力学等学科所必需的重要基础信息,重力场测绘是获取地球重力场信息的有效手段.相比于卫星、海洋、航空重力场测绘,车载重力场测绘具有灵活性强、空间分辨率高、精度高等优点.基于相对重力仪和高精度绝对重力基准点可以实现陆域小范围重力场测绘,但相对重力仪存在零点漂移,不适用于长基线、大范围的陆域测绘.本文基于小型化原子重力仪搭建了一套车载绝对重力快速测绘系统,在郊区安静外场环境,由12个测点约3 km的测绘结果评估仪器的内符合精度为0.123 mGal(1 Gal=10^(–2)m/s^(2)),外符合精度为0.112 mGal,并在闹市复杂外场环境下实现了单点调节时间小于2 min,有效测量时间5 min的快速绝对重力测量,通过19个测点跨区约24 km的重力场快速测绘,评估仪器的内符合精度为0.162 mGal,外符合精度为0.169 mGal.最后将原子重力仪的外场重力场测绘数据与卫星重力模型计算的数据进行了比较,发现两者的自由空间重力异常数据的整体变化趋势相吻合.本文为外场绝对重力场快速测绘提供了一种新的方案.

The information about Earth’s gravity field is an important basic information necessarily for geodesy,geophysics,geodynamics and other disciplines.The mapping of gravity field is an effective mean to obtain the gravity field information.Compared with the surveying of gravity field based on satellite,ship,and airplane,vehicle-mounted gravity mapping has advantages of strong flexibility,high spatial resolution and high accuracy.A short baseline or a small-scale gravity field mapping can be realized based on the combination of relative gravimeters and the high-precision absolute gravity reference point.However,this method is not suitable for the situation of a long baseline or a large-scale gravity field surveying due to the drift of relative gravimeter.In this work,a vehicle-mounted system for rapid surveying of the absolute gravity field is built up based on a miniaturized atomic gravimeter.The inner precision of the instrument is evaluated to be 0.123 mGal,and the outer precision is 0.112 mGal in a field test which contains 12 points for 3 km distance.Furthermore,with this system,the absolute gravity data are obatined within 2 min for adjusting and 5 min for measuring in downtown for each measured point.A rapid surveying of absolute gravity field for 19 points is carried out and the route covers 24 km.The inner precision of the instrument is evaluated to be 0.162 mGal,and the outer precision is0.169 mGal.Finally,the free-air gravity anomalies obtained from the measured data of atomic gravimeter and the fitting results of satellite gravity model are analyzed,and it is found that the trends of changing are basically consistent with each other.This paper provides a new proposal for the rapid surveying of the absolute gravity field.