近年来,随着全球导航卫星系统(Global navigation satellite systems, GNSS)的发展,兴起了一种基于信噪比(Signal to Noise Ratio,SNR)的GNSS多路径遥感技术(GNSS-Multipath Reflectometry,GNSS-MR)。该技术利用GNSS接收机即可获取反射面信息,在雪深反演中具有信号源丰富、采样率高等优势。但是目前许多GNSS接收机并不记录SNR观测值。为了使这些接收机也具有雪深监测能力,文章提出了一种基于信号强度(Signal Strength Indicator,SSI)的多模多频GNSS-MR雪深反演融合方法。实验研究选取美国阿拉斯加州SG27测站；结果表明：四大全球卫星系统的多频点SSI数据均能反演雪深。经多模多频GNSS-MR雪深反演融合后,SSI反演结果与雪深实测序列间的均方根误差为2.36cm,相关系数为0.98。同时,实验研究也进行了基于SNR数据的多模多频GNSS-MR雪深反演,发现：SSI反演结果和SNR反演结果具有一致性,实验验证了基于SSI的多模多频GNSS-MR雪深反演融合方法的可行性和有效性。

In recent years, with the development of Global Navigation Satellite Systems (GNSS), a GNSS-Multipath Reflectometry (GNSS-MR) technique based on Signal to Noise Ratio (SNR) has been developed.SThis technology can obtain the information of the reflector by using GNSS receiver, and has the advantages of abundant signal sources and high sampling rate in snow depth inversion.SBut now many GNSS receiver do not record SNR observations.SIn order to make these receivers also have the ability of snow depth monitoring, a multi-mode and multi-frequency GNSS-MR snow depth inversion fusion method based on Signal Strength Indicator (SSI) is proposed in this paper.SThe experimental station is SG27 in Alaska, United States.The results show that the multi-frequency SSI data of four global satellite systems can retrieve snow depth.SAfter multi-mode and multi-frequency GNSS-MR snow depth inversion fusion, the root mean square error between the SSI inversion results and the measured snow depth series is 2.36cm, and the correlation coefficient is 0.98.SAt the same time, the multi-mode and multi-frequency GNSS-MR snow depth inversion based on SNR data is also carried out in the calculation example, and it is found that:The results of SSI inversion are consistent with those of SNR inversion, and the feasibility and effectiveness of multi-mode and multi-frequency GNSS-MR snow depth inversion fusion based on SSI are verified by experiments.S