在冻结参量探测中，L波段穿透性更强，相比其他微波波段更具优势，但当前对于L波段微波辐射响应深度研究相对较少，冻结条件下土壤的微波辐射响应特性还有待于进一步明晰。对此，本研究以东北典型冻土区中的黑土为研究对象，在冬季自然冻结条件下，使用频率为1.414GHz的双极化L波段微波辐射计对不同初始含水率的黑土进行近场试验，通过试验结果分析黑土在冻结过程中以及冻结后的微波辐射响应深度变化。结果发现：在冻结过程中，10%和30%含水率的土壤L波段微波响应深度均大于5cm，与此同时，土壤含水率依然对亮温起主导作用。在冻结之后，初始含水率通过影响未冻水含量进而影响L波段微波辐射响应深度，试验测得，初始含水率分别为0%（寒土）、10%的黑土冻结后微波辐射响应深度分别约为105cm和50cm，初始含水率为20%，30%的黑土冻结后微波辐射响应深度分别在35~50cm和25~35cm之间。除此之外，试验同时证实了冻土微波辐射响应深度高于基于模型计算的穿透深度。以上研究结论对于冻土参量遥感反演领域具有重要参考价值。

In the field of frozen parameter detection, the L-band has stronger penetration capabilities compared to other microwave bands, offering significant advantages. However, there is currently a relative lack of in-depth research on the microwave radiation response of L-band under frozen conditions, and the characteristics of microwave radiation response of soil under frozen conditions require further clarification. In this study, we focus on the black soil in a typical frozen soil area in Northeast China as the subject of research. Under natural freezing conditions in winter, we conducted near-field experiments on black soil with different initial moisture contents using a dual-polarized L-band microwave radiometer with a frequency of 1.414 GHz. By analyzing the experimental results, we examined the changes in the microwave radiation response depth of black soil during and after the freezing process. The findings indicate that during the freezing process, the L-band microwave response depth of soils with moisture contents of 10% and 30% consistently exceeds 5 cm, and soil moisture content continues to play a dominant role in determining brightness temperature. After freezing process, the initial moisture content affects the L-band microwave radiation response depth by influencing the amount of unfrozen water. The experiments measured that the microwave radiation response depth of black soil after freezing with initial moisture contents of 0% (cold soil) and 10% is approximately 105 cm and 50 cm, respectively. For black soil with initial moisture contents of 20% and 30%, the microwave radiation response depth after freezing is between 35~50 cm and 25~35 cm, respectively. In addition, the experiments also confirmed that the microwave radiation response depth of frozen soil is higher than the penetration depth calculated based on models. The conclusions of this study have significant reference value for the field of remote sensing inversion of frozen soil parameters.