罗斯海海域大地水准面异常的成因研究  

Study on the origin of geoid anomalies in the Ross Sea area

作　　者：崔荣花 方剑 王勇 CUI RongHua;FANG Jian;WANG Yong(State Key Laboratory of Geodesy and Earth′s Dynamics,Innovation Academy for Precision Measurement Science and Technology,Chinese Academy of Sciences,Wuhan 430077,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院精密测量科学与技术创新研究院,大地测量与地球动力学国家重点实验室,武汉430077 [2]中国科学院大学,北京100049

出　　处：《地球物理学报》2021年第4期1279-1290,共12页Chinese Journal of Geophysics

基　　金：中国科学院战略先导研究专项-B类(XDB18010304);国家自然科学基金项目(41874096,41874091);武汉大学地球空间环境与大地测量教育部重点实验室开放基金项目(19-01-01)联合资助.

摘　　要：本文利用数值法求解瞬时地幔对流问题以模拟大地水准面异常.利用两个较新的S波速度异常层析模型SEMUCB_WM1和TX2019slab,将其转换为密度异常作为控制方程的浮力驱动项;采取的黏度结构模型中,上下地幔的黏度比为1∶50.为了研究地幔不同结构对罗斯海海域大地水准面异常的影响,分别提取上、下地幔的密度异常正/负值,作为对流控制方程的输入项,计算相应的模拟大地水准面异常.将模拟大地水准面异常与观测值进行对比,发现罗斯海海域的大地水准面异常主要来自下地幔及上地幔的负密度(波速)异常,下地幔正密度异常对该区域大地水准面负异常也有一定的贡献.本文认为,地幔密度负异常在罗斯海海域大地水准面异常的形成中占据主导作用,地幔对流的动力学效应对该区域大地水准面异常的形成影响较弱.In this paper,a numerical method is used to solve the instantaneous mantle convection to simulate geoid anomalies.Two recent S-wave velocity anomaly tomography models-SEMUCB_WM1 and TX2019slab are employed to convert geoid anomalies into density anomalies as the buoyancy driving term in the governing equation.The viscosity ratio of the upper and lower mantle used in this study is 1∶50.In order to study the influence of different structures of the mantle on geoid anomalies in the Ross Sea area,the positive/negative density anomalies of the upper and lower mantles are extracted respectively as input terms in the convection governing equations,and then geoid anomalies are calculated.Comparing the modeling geoid anomalies with observations shows that the geoid anomalies in the Ross Sea area mainly come from the negative density(seismic wave velocity)anomalies of the lower and upper mantle,and the positive density anomalies in the lower mantle also has a certain contribution to the negative geoid anomalies in this area.We suggest that negative mantle density anomalies play a dominant role in the formation of geoid anomalies in the Ross Sea,and the dynamic effect of mantle convection has a smaller influence on the formation of geoid anomalies in this area.

关 键 词：瞬时地幔对流 罗斯海 大地水准面异常 数值模拟 

分 类 号：P312[天文地球—固体地球物理学]