On the nature of low-latitude Es influencing the genesis of equatorial plasma bubble

摘要

The potential influence of the postsunset low-latitude sporadic E (E_s) on the genesis of equatorial plasma bubble (EPB) has been investigated using observations made with the Gadanki radar and two ionosondes, one located at the magnetic equator providing the F layer characteristics and another at magnetically low-latitude providing the Es parameters. Observations revealed that the occurrence of EPB was associated with either the disruption of Es or presence of nonblanketing-type E_s or intermittently occurring blanketing E_s at low-latitude. In contrast, when blanketing E_s occurred for a relatively long duration in the sunset hours, EPB did not occur. Model computation clearly reveals that the growth of the Rayleigh-Taylor instability depends very much on the thickness, height, and shape of electron density profile of the E_s layer. The above findings thus suggest that low-latitude E_s variability plays decisive role on the day-to-day variability of EPB through the growth rate of the Rayleigh-Taylor instability.