All‐Sky Interferometric Meteor Radar Observations of Zonal Structure and Drifts of Low‐Latitude Ionospheric E Region Irregularities

Abstract

All-sky interferometric meteor radar has been operated worldwide for the measurements of neutral winds in the mesopause region. In this paper, we employ an all-sky meteor radar and an ionospheric radar, which are situated at Ledong (18.4°N,109°E) and Sanya (18.3°N,109.6°E), respectively, and both have the interferometry capability, to study the zonal structure and drifts of ionospheric E region irregularities producing continuous and quasiperiodic echoes. We use the collocated optical meteor observations to calibrate the radar system phase offsets for interferometry measurements. A good correspondence between the irregularity measurements from both radars was found. The observations show that the quasiperiodic striations with both negative and positive slopes in radar range-time-intensity maps were produced by spatially separated irregularity structures, which drift through the radar field of view. The continuous echoes were due to irregularities generated locally. Specifically, comparing with ionospheric radar, all-sky meteor radar has a much wider field of view that can provide E region irregularity information over a large zonal region of more than 300 km. It is suggested that all-sky meteor radar provides a capability to probe ionospheric E region irregularities and to trace their movements. Plain Language Summary The interferometry observations of ionospheric E regionirregularities from a conventional all-sky meteor radar and an ionospheric radar are reported. The results show the feasibility of making ionospheric E region irregularity measurements and tracing their movements over a large zonal field of view of more than 300 km with conventional meteor radars. Since there are tens of such meteor radars continuously operated at middle and low latitudes, the interferometry observations with these meteor radars would contribute to a better understanding of worldwide ionospheric E region irregularities. 10.1029/2019EA000884Key Points:• Interferometry observations of ionospheric E region irregularities are made with an all-sky meteor radar • The zonal structure and movements of E region irregularities over a zonal field of view of more than 300 km are revealed by meteor radar • Comparison of meteor radar E region irregularity observations with ionospheric radar shows a good correspondenceCorrespondence to:

The Evolution of Complex Es Observed by Multi Instruments Over Low‐Latitude China

“…Thus, the ranges are dependent upon which part of the irregularities generated the backscatter, which may lead to an overestimate or underestimate. In spite of this, the range rate of radar backscatter echoes was comparable to the drifting velocity of strong E s structures and was consistent with previous studies (e.g., Chu & Wang, 1997; Haldoupis et al, 2001; Wang et al, 2019).…”

“…But the echo striations in previous studies usually had smaller range extent limited to relatively narrow radar beam widths. Recently, the newly developed capability of all‐sky meteor radar in detecting E region irregularities has illustrated V‐shape echoes generated by drifting E s patches, which extended to more than 200 km owing to the extraordinary wide radar beam (Wang et al, 2019; Xie et al, 2019). Though the beam width of the Sanya VHF radar is considerably wide, it is much narrower than that of all‐sky meteor radars.…”

IONISE: An Ionospheric Observational Network for Irregularity and Scintillation in East and Southeast Asia

“…It is relevant to mention that there are some instruments which are not primary for ionospheric observation in the IONISE stations, such as all‐sky meteor radar, which can also be employed for deriving ionospheric information. Whereas all‐sky meteor radar is usually employed to obtain neutral winds from the radial velocities of specular meteor echoes, Xie et al (2019) and Wang et al (2019) developed the capability for observing ionospheric E ‐region irregularities under the all‐sky meteor mode. Most of the IONISE sites, including the chains of BD‐GEO TEC/scintillation receivers, were operated after 2018.…”

Morphological Characteristics of Thousand‐Kilometer‐Scale Es Structures Over China

“…However, the horizontal shape of E s structures has remained unclear for decades. Although observations from radars and airglow imagers revealed the quasiperiodic and wave‐like feature of E s (e.g., Djuth et al., 1999; Hysell et al., 2009), these results were mostly for small‐scale structures limited within the radar‐/airglow‐illuminated volume, which usually suffer from a low spatial distribution, for example, less than 400 km (Wang et al., 2019) that is unfavorable for depicting the E s morphology in a large scale of thousands of kilometers. Thus, despite E s layers are observed simultaneously or sequentially at stations separated by hundreds of kilometers or more, it's hard to distinguish whether these E s layers are due to the same large‐scale structure or small‐scale E s patches coincidently occurred simultaneously.…”