We have studied the electric \(\vec {E}\) and magnetic \(\vec {B}\) fields by displaying the arrival directions through a 2D image named spectral-directionalogram (SD-gram). This technique maps electromagnetic field directions in time and frequency space. We tested the method through modeling experiments. An exclusive case is explained theoretically. In addition, method is applied on the two field data sets. One was acquired on the land and other in the ocean. The land data, is studied for the 50 Hz and harmonics. The frequencies are continuous in the direction during a time range, while splittings are observed during the other. In the second example, we have used marine electromagnetic data. The spectrogram suggests two anomalies, one close to 1 Hz and the other having a broad spectral range between 1 to 0.08 Hz. We hypothesize two possible causative sources, microseisms and degassing of a mud volcano. Out of these two choices, one can be easily falsified using the SD-gram. These examples highlight the usefulness of the technique in the data analysis. Moreover, the electromagnetic noise caused by the ocean waves have different spectral damping characteristics compared to those of plane waves. Therefore, we are proposing a new damping relation for the ocean, where dispersion is a dominant case.

我们研究了电\(\vec {E}\)和磁\(\vec {B}\)通过名为光谱方向图 (SD-gram) 的 2D 图像显示到达方向。这种技术在时间和频率空间映射电磁场方向。我们通过建模实验测试了该方法。从理论上解释了一个排他性的情况。此外，该方法应用于两个字段数据集。一种是在陆地上获得的，另一种是在海洋中获得的。陆地数据是针对 50 Hz 和谐波进行研究的。频率在一个时间范围内的方向上是连续的，而在另一个时间范围内观察到分裂。在第二个例子中，我们使用了海洋电磁数据。频谱图表明存在两种异常情况，一种接近 1 Hz，另一种具有 1 到 0.08 Hz 之间的宽频谱范围。我们假设两个可能的原因，泥火山的微震和脱气。在这两种选择中，使用 SD-gram 可以轻松伪造其中一种。这些示例突出了该技术在数据分析中的有用性。此外，与平面波相比，海浪引起的电磁噪声具有不同的光谱阻尼特性。因此，我们为海洋提出了一种新的阻尼关系，其中弥散是主要情况。