Climatology of successive equatorial plasma bubbles observed by GPS ROTI over Malaysia

Abstract

The occurrence rate of the equatorial plasma bubble (EPB) with season, solar activity, and geomagnetic conditions are investigated using long‐term data sets of Malaysia Real‐Time Kinematics Network (MyRTKnet) from 2008 to 2013. The rate of TEC (total electron content) change index (ROTI) in 5 min was derived from MyRTKnet data to detect the EPB with scale sizes around tens of kilometers. Then, the daily east‐west cross sections of 2‐D ROTI maps were used to examine the EPB features over 100°E–119°E longitudes. The EPBs tend to occur successively in one night along the observational coverage of MyRTKnet during equinoxes in high solar activity years. The perturbations in a form of wavelike structures along the observed longitudes might be responsible for the development of successive EPBs due to high growth rate of the Rayleigh‐Taylor instability (RTI) process. On the contrary, the occurrence of successive EPBs is infrequent and the occurrence day of EPB remains active during equinoctial months in low solar activity years. The small growth rate of the RTI process during low solar activity years might require a strong seed perturbation to generate the EPB structure. The occurrence probability of the EPB was found to be similar during quiet and disturbed geomagnetic conditions. The results imply that the strong perturbations play an important role in the development of the EPB in low solar activity years. Nonetheless, the high growth rate of the RTI could cause the successive occurrence of the EPB in high solar activity years.

Characteristics of Equatorial and Low‐Latitude Plasma Irregularities as Investigated Using a Meridional Chain of Radio Experiments Over India

“…In the presence of these plasma irregularities, radio waves that traverse through the ionosphere undergo radio scintillations, a key concern of communication and navigation community. These irregularities are correlated well with the solar flux and the geomagnetic activity (Abdu, ; Buhari et al, ; Chandra & Rastogi, ; Gentile et al, ; Huang et al, ; Rastogi, ; Ray & DasGupta, ). Though many aspects of these irregularities have been understood by now, still key issues like day‐to‐day and intraseasonal variabilities of these irregularities are yet to be realized (e.g., Kelley et al, ).…”

Ionospheric Irregularities and Acoustic/Gravity Wave Activity Above Low‐Latitude Thunderstorms

“…Even though the scale sizes probed in a scintillation measurement and a ROTI measurement are orders of magnitude different, the cascading nature of ionospheric instabilities allows both to be a good proxy of the presence of small scale instabilities in the ionosphere. ROTI measurements have also been used as a proxy for plasma bubbles (equatorial spread F , ESF) on the scale size of tens of kilometers (Buhari et al, ). In the GPS TEC data used in this paper, as in those data used in the ROTI measurements, ionospheric turbulence of various scale sizes appears as temporal fluctuations.…”

Coordinated Ground‐Based and Space‐Based Observations of Equatorial Plasma Bubbles

“…During quiet times, the prereversal enhancement (PRE) of the zonal electric field is responsible for the enhanced upward E × B drift after sunset, which elevates the ionospheric height and subsequently amplifies the growth rate of R-T The morphological features and spatial/temporal variability of EPBs have been widely investigated via case studies and statistical analysis using different observational methods. Moreover, with the fast-growing and global availability of ground-based Global Navigation Satellite Systems (GNSS) measurements and space-based radio occultation data, the evolution characteristics of EPBs can be monitored continuously on both global or regional scales (Aa et al, 2018;Barros et al, 2018;Buhari et al, 2014Buhari et al, , 2017Cherniak et al, 2014;Katamzi-Joseph et al, 2017;Ma & Maruyama, 2006;Nishioka et al, 2008;Takahashi et al, 2015). The spatial variation of EPBs can be derived from the dark streaks of emission depletion in optical observations from ground-based all-sky imagers (ASIs) or space-based ultraviolet (UV) imaging spectrographs (Comberiate & Paxton, 2010;Hickey et al, 2018;Kelley et al, 2003;Kil et al, 2009;Makela, 2006;Martinis et al, 2015;Otsuka et al, 2002;Shiokawa et al, 2015).…”