密度误差对重力梯度正演精度的影响

Influences of density error on gravity gradient forward results

深入分析了重力梯度正演过程中密度误差对正演精度的影响.以地壳平均密度常数为参考,利用3种密度模型模拟地形的密度变化,建立了密度误差模型.然后分别对同一DEM进行了正演计算,具体分析密度误差对正演精度的影响.数值分析结果表明:a.密度误差对正演结果影响明显,当密度误差为0.2g/cm3时,梯度误差在10E左右;b.密度引起的梯度误差与地形相关,表现为误差数值与地形起伏成正比,变化趋势受地形调制;c.地形仍是梯度变化的主要因素,减小密度误差,DEM正演重力梯度数据可取得满意的精度.

The influences of density error on gravity gradient forward results were analyzed.Three density variation models applied to the same digital elevation model（DEM） in forward calculation were used in the techniques proposed.Then corresponding results to a constant density model were compared respectively.Those differences indirectly reflect the impact of density error on forward results.Our numerical analysis shows density error has significant influence on forward results.Gradient difference approximates 10E when density error was.In addition,the difference was also influenced by terrain attributes,whose value proportional to terrain undulation and trend was also modulated by terrain.Comparing influence of density with terrain,latter part was still a major factor that causes change of gradient,so once density error was reduced,forward method may provide satisfactory gradient data with present DEM.