The split-spectrum method (SSM) can largely isolate and correct for the ionospheric contribution in the L-band interferometric synthetic aperture radar (InSAR). The standard SSM is performed on the assumption of only the first-order ionospheric dispersive effect, which is proportional to the total electron content (TEC). It is also known that during extreme atmospheric events, either originated from the ionosphere or in the troposphere, other dispersive effects do exist and potentially provide new insights into the dynamics of the atmosphere, but there have been few detection reports of such signals by InSAR. We apply L-band InSAR into heavy rain cases and examine the applicability and limitation of the standard SSM. Since no events such as earthquakes to cause surface deformation took place, the non-dispersive component is apparently attributable to the large amount of water vapor associated with heavy rain, whereas there are spotty anomalies in the dispersive component that are closely correlated with the heavy rain area. The ionosonde and Global Navigation Satellite System (GNSS) rate of total electron content index (ROTI) map both show little anomalies during the heavy rain, which suggests few ionospheric disturbances. Therefore, we interpret that the spotty anomalies in the dispersive component of the standard SSM during heavy rain are originated in the troposphere. While we can consider two physical mechanisms, one is runaway electron avalanche and the other is the dispersive effect due to rain, comparison with the observations from the ground-based lightning detection network and rain gauge data, we conclude that the rain dispersive effect is spatiotemporally favorable. We further propose a formulation to examine if another dispersive phase than the first-order TEC effect is present and apply it to the heavy rain cases as well as two extreme ionospheric sporadic-E events. Our formulation successfully isolates the presence of another dispersive phase during heavy rain that is in positive correlation with the local rain rate. In comparison with other dispersive phases during Sporadic-E episodes, the dispersive heavy rain phases seem to have the same order of magnitude with the ionospheric higher order effects.

分谱法 (SSM) 可以在很大程度上隔离和校正 L 波段干涉合成孔径雷达 (InSAR) 中的电离层贡献。标准 SSM 仅基于一阶电离层色散效应的假设执行，该效应与总电子含量 (TEC) 成正比。众所周知，在源自电离层或对流层的极端大气事件期间，确实存在其他色散效应，并可能为大气动力学提供新的见解，但 InSAR 对此类信号的检测报告很少。我们将 L 波段 InSAR 应用于大雨情况，并检查标准 SSM 的适用性和局限性。由于没有发生地震等导致地表变形的事件，非弥散分量明显归因于与大雨相关的大量水汽，而弥散分量中存在与暴雨区域密切相关的点状异常。电离层探测器和全球导航卫星系统（GNSS）总电子含量指数（ROTI）图在大雨期间均未显示异常，表明电离层干扰很少。因此，我们认为大雨期间标准SSM色散分量的点状异常起源于对流层。虽然我们可以考虑两种物理机制，一种是失控的电子雪崩，另一种是由于降雨引起的色散效应，与地基闪电探测网络和雨量计数据的观测结果相比，我们得出结论，雨水分散效应在时空上是有利的。我们进一步提出了一个公式来检查是否存在除一阶 TEC 效应之外的另一个分散阶段，并将其应用于大雨情况以及两个极端的电离层零星 E 事件。我们的配方成功地隔离了与当地降雨率呈正相关的大雨期间另一个分散阶段的存在。与零星 E 发作期间的其他弥散阶段相比，弥散大雨阶段似乎与电离层高阶效应具有相同的数量级。我们进一步提出了一个公式来检查是否存在除一阶 TEC 效应之外的另一个分散阶段，并将其应用于大雨情况以及两个极端的电离层零星 E 事件。我们的配方成功地隔离了与当地降雨率呈正相关的大雨期间另一个分散阶段的存在。与零星 E 发作期间的其他弥散阶段相比，弥散大雨阶段似乎与电离层高阶效应具有相同的数量级。我们进一步提出了一个公式来检查是否存在除一阶 TEC 效应之外的另一个分散阶段，并将其应用于大雨情况以及两个极端的电离层零星 E 事件。我们的配方成功地隔离了与当地降雨率呈正相关的大雨期间另一个分散阶段的存在。与零星 E 发作期间的其他弥散阶段相比，弥散大雨阶段似乎与电离层高阶效应具有相同的数量级。