地球物理学报 ›› 2016, Vol. 59 ›› Issue (7): 26502662.doi: 10.6038/cjg20160728
郑婉秋1, 孟小红1, 刘建红2, 王建1
ZHENG Wan-Qiu1, MENG Xiao-Hong1, LIU Jian-Hong2, WANG Jian1
摘要: 有限差分时间域正演是弹性波逆时偏移和全波形反演的基础,正演的计算精度也控制着偏移结果的准确性,若精度不高,则在偏移、反演后会带来假象.为了有效提高正演精度,本文结合窗函数优化方法,在窗函数截断伪谱法空间褶积序列以逼近有限差分算子的基础上,提出了一种基于Chebyshev窗的余弦调制模型,在原始Chebyshev窗的基础上引入了调制次数和调制范围,通过调节这两个参数可以人工可视化的调节截断误差,新的窗函数继承了Chebyshev窗的特点,在不明显降低截断谱范围的基础上明显降低了截断误差.本文针对不同正演阶数N,给出了一组经验调制系数,并通过数值模拟方法,对比了新方法、改进二项式窗和基于最小二乘优化方法的正演效果.结果表明,基于余弦调制的Chebyshev窗控制数值频散的能力更强,在大网格下可以得到更精确的正演结果.从经济角度分析,该方法减小了计算花费,提高了计算效率.
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