In this paper, we address the day‐to‐day variation in the development of equatorial plasma bubble (EPB) using simultaneous observations made by the 30 MHz Gadanki Ionospheric Radar Interferometer (GIRI) and ionosonde (DPS‐4D) from Gadanki and C/NOFS. We show that wave‐like variations with horizontal wavelengths of 200–660 km observed prior to sunset have a close connection with EPB spacings. We also show that the locations of EPB development at their origins, which varied on a day‐to‐day basis, were as large as 2600 km from Gadanki. A detailed analysis clearly reveals the cause of such variability and provides clue as to where the background ionospheric conditions led to the growth of the Rayleigh Taylor instability (RTI) generating EPB and where they failed. Results clearly show that while ionosonde observations show great potential for understanding day‐to‐day variation and predicting EPB development overhead (within ±1° longitude), they are inadequate to assess the growth potential of EPB at longitudes away from a longitude zone of about ±1° from overhead. A detailed analysis suggests that the day‐to‐day variability in EPB development is governed by large scale wave structures (LSWS) and it is inferred that the LSWS troughs (low electron density) are the sites for the EPB development. Results further suggest that LSWS with horizontal wavelength of 200–660 km acts as seed for the growth of the RTI resulting in EPBs with same spacing. While the sources of LSWS remain to be identified, it is suggested that observations with longitudinally distributed ground‐based sensor, viz., ionosonde, preferably separated by 250–300 km, would be an immediate step forward in this effort.

中文翻译：

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关于赤道等离子泡日常发生的评估

在本文中，我们利用Gadanki和C / NOFS。我们表明，日落之前观察到的水平波长为200–660 km的波状变化与EPB间距密切相关。我们还显示，EPB的发源地每天变化，距加丹基2600公里。详细的分析清楚地揭示了这种可变性的原因，并提供了有关背景电离层条件导致产生瑞利泰勒不稳定性（RTI）的EPB增长以及它们失败的线索。结果清楚地表明，尽管离子探空仪观测结果显示出了解日常变化和预测EPB发育开销（在±1°以内）的巨大潜力，但它们不足以评估经度在大约经度区域以外的地方的EPB的生长潜力。距顶部±1°。详细的分析表明，EPB发展的日常变化受大规模波结构（LSWS）的控制，并且可以推断出LSWS槽（低电子密度）是EPB发展的场所。结果进一步表明，水平波长为200–660 km的LSWS作为RTI生长的种子，导致EPB具有相同的间距。虽然LSWS的来源仍有待确定，但建议使用纵向分布的地面传感器（即，离子探空仪，