Vertical rise velocity of equatorial plasma bubbles estimated from Equatorial Atmosphere Radar (EAR) observations and HIRB model simulations

The vertical rise velocity (Vr) and maximum altitude (Hm) of equatorial plasma bubbles (EPBs) were estimated using the two‐dimensional fan sector maps of 47 MHz Equatorial Atmosphere Radar (EAR), Kototabang, during May 2010 to April 2013. A total of 86 EPBs were observed out of which 68 were postsunset EPBs and remaining 18 EPBs were observed around midnight hours. The vertical rise velocities of the EPBs observed around the midnight hours are significantly smaller (~26–128 m/s) compared to those observed in postsunset hours (~45–265 m/s). Further, the vertical growth of the EPBs around midnight hours ceases at relatively lower altitudes, whereas the majority of EPBs at postsunset hours found to have grown beyond the maximum detectable altitude of the EAR. The three‐dimensional numerical high‐resolution bubble (HIRB) model with varying background conditions are employed to investigate the possible factors that control the vertical rise velocity and maximum attainable altitudes of EPBs. The estimated rise velocities from EAR observations at both postsunset and midnight hours are, in general, consistent with the nonlinear evolution of EPBs from the HIRB model. The smaller vertical rise velocities (Vr) and lower maximum altitudes (Hm) of EPBs during midnight hours are discussed in terms of weak polarization electric fields within the bubble due to weaker background electric fields and reduced background ion density levels. Plain Language Summary Equatorial plasma bubbles are plasma density irregularities in the ionosphere. The radio waves passing through these irregular density structures undergo severe degradation/scintillation that could cause severe disruption of satellite‐based communication and augmentation systems such as GPS navigation. These bubbles develop at geomagnetic equator, grow vertically, and elongate along the field lines to latitudes away from the equator. The knowledge on bubble rise velocities and their maximum attainable altitudes improves the accuracy of scintillation forecasting at latitudes away from the equator and helps in mitigating the errors in satellite‐based augmentation systems. Key Points Vertical rise velocities of EPBs estimated from EAR observations are consistent with the nonlinear evolution of EPBs simulated by HIRB model The vertical rise velocities and maximum attainable altitudes of midnight EPBs are significantly smaller than those of postsunset EPBs Smaller rise velocities of midnight EPBs are due to both weak backg