Density profile of the B18_2012 firn core

Density was measured by micro-focus Computer Tomography with a resolution of 0.1mm and subsequently smoothed with a Gaussian filter with sigma 2 cm.采用微焦点计算机断层扫描（micro-focus Computer Tomography）进行密度测定，扫描分辨率为0.1毫米；随后使用标准差为2 cm的高斯滤波器对测量数据进行平滑处理。