Soil moisture plays a pivotal role in terrestrial water circulation, energy transfer, and mass exchange. The X-band radiometer on-board Fengyun-3B and -3C satellites have been used for soil moisture retrieval since 2011. In this study, the spatial and temporal integrity of all available Fengyun-3 series soil moisture products were evaluated, and the data accuracy was validated against four in-situ measurements ascertained globally. The validation results reveal that: (1) The ascending Fengyun-3B soil moisture retrievals express higher spatial coverage percentages than others, and a higher temporal coverage percentage appears at 20–60 °N and 20–50 °S in summer. (2) The soil moisture products derived from both Fengyun-3B and -3C satellites reveal superior goodness of fit and smaller bias in the northern hemisphere in-situ measurements than in the southern hemisphere. In particular, the satellite retrieved pixel scale soil moisture datasets possesses a better correlation to small scale networks with densely distributed stations. In the southern hemisphere, the bias was positively correlated with the vegetation index and negatively correlated to land surface temperature, and this regularity may act as a reference for Fengyun-3 soil moisture correction. Moreover, the Fengyun-3 soil moisture products reveal positive responses to precipitation, and the memory of soil moisture to precipitation could last for at least 5 days. (3) The X-band signals were gradually impacted by increasing vegetation optical depth, leading to obvious overestimations. Further corrections, including hardware and software, are urgently required to enhance the anti-interference and robustness of the X-band signal.

土壤水分在陆地水循环，能量转移和质量交换中起着关键作用。自2011年以来，风云3B和-3C卫星上的X波段辐射计已用于土壤水分的检索。在这项研究中，评估了所有可用的风云3系列土壤水分产品的时空完整性，并提供了数据相对于全球确定的四个原位测量结果验证了准确性。验证结果表明：（1）上升的风云3B土壤水分反演的空间覆盖率高于其他，夏季20–60°N和20–50°S时空覆盖率较高。（2）与南半球相比，来自风云3B和-3C卫星的土壤水分产物在北半球实地测量中显示出优越的拟合度和较小的偏差。特别是，卫星检索的像素级土壤湿度数据集与站点密集分布的小型网络具有更好的相关性。在南半球，偏差与植被指数正相关，与土地表面温度负相关，这一规律性可作为风云3号土壤水分校正的参考。而且，风云3号土壤水分产物对降水表现出正响应，并且土壤水分对降水的记忆至少可以持续5天。（3）X波段信号逐渐受到植被光学深度的影响，导致明显的高估。迫切需要进一步的校正，包括硬件和软件，以增强X波段信号的抗干扰性和鲁棒性。