In this paper, we study on the precursor seed structures well before the prospective occurrence of equatorial plasma bubble (EPB). We use the scanning mode observations made by the 30‐MHz Gadanki Ionospheric Radar Interferometer for estimating interbubble spacing and high time resolution observations made by a collocated digisonde for inferring horizontal wavelength of wave‐like variations prior to the onset of EPB. Horizontal wavelength of wave‐like variations has been inferred from plasma density variations and height variations of isodensity contours; both show consistent results. Remarkable agreement has been found between the estimated horizontal wavelength and interbubble spacing, which demonstrates the potential of digisonde in providing relevant seed structure for a prospective EPB formation. Further analysis based on observational results and numerical simulation of collisional interchange instability shows that while the eventual formation of EPB has a strong bearing on the height of the F layer and density gradient scale length, the growth perspective of the EPB depends on the seed wavelength. These results are presented and discussed keeping the future prospective of EPB forecasting/nowcasting.

中文翻译：

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日落前的波结构与气泡间距的关系：赤道等离子泡的播种角度

在本文中，我们在预期发生赤道等离子气泡（EPB）之前就对前体种子结构进行了研究。我们使用30 MHz Gadanki电离层雷达干涉仪进行的扫描模式观测来估计气泡间距，并使用并置的数码二极管进行高时间分辨率观测，以推断出EPB出现之前波状变化的水平波长。从等密度线的等离子体密度变化和高度变化可以推断出波状变化的水平波长。两者均显示一致的结果。在估计的水平波长和气泡间距之间发现了显着的一致性，这表明了地高辛在为预期的EPB形成提供相关种子结构方面的潜力。F层和密度梯度尺度长度不同，EPB的生长角度取决于种子波长。呈现并讨论了这些结果，从而使EPB的预测/临近预报保持了未来的前景。