The Qujing incoherent scatter radar: system description and preliminary measurements

Zhang²,

Zhang

et al. 2020

JGR Space Physics

Self Cite

The day-to-day variability of the ionospheric electron density and its longitudinal gradient challenges our description and understanding of the ionosphere, which is also essential for reliable applications of the Global Navigation Satellite System (GNSS). In this paper we conduct a case study of the anomalous enhancements in ionospheric electron density and its longitudinal gradient to reveal the spatial extent and related drivers of the enhancements. The ionospheric data analyzed include the vertical total electron content (TEC) by the Global Navigation Satellite System receivers, peak electron density (NmF2) and height (hmF2) of the F layer by a chain of ionosondes, and electron density profiles recorded by the Qujing incoherent scatter radar (103.8°E, 25.6°N) during the period from 29 May to 2 June 2015. Electron density enhancements are found in the region around the northern crest of equatorial ionization anomaly on the first 2 days of June 2015. It is the first time to report that, during the anomalous enhancement, the increase in electron density over Qujing depends on altitude, being stronger at higher altitudes. Further, there are strong longitudinal gradients in vertical TEC in the regions during the course of the electron density enhancements. Low latitude hmF2 and especially the equatorial electrojet become much larger on the enhancement days, implying the important role of equatorial zonal electric fields in the formation of the electron density enhancements at low latitudes.

Section: Datamentioning

confidence: 99%

A Case Study of the Enhancements in Ionospheric Electron Density and Its Longitudinal Gradient at Chinese Low Latitudes

Zhang²,

Zhang

et al. 2020

JGR Space Physics

Self Cite

“…The behaviors of NmF 2 and hmF 2 in Liu et al () and Jiang et al () are different from the general view that electron density should decay faster if the ionosphere is at a lower altitude when no external ionization is involved. Further, in a paper which provide a general description of a new‐built incoherent scatter radar (ISR) at Qujing (103.8°E, 25.6°N) of China, Ding et al () reported that the Qujing ISR frequently observed enhancements in electron density in the ionospheric F region during the afternoon‐evening period. Figure 12 of Ding et al (), for example, revealed exactly the same feature that NmF 2 enhances when hmF 2 descends to lower altitudes.…”

Section: Introductionmentioning

confidence: 99%

“…Further, in a paper which provide a general description of a new‐built incoherent scatter radar (ISR) at Qujing (103.8°E, 25.6°N) of China, Ding et al () reported that the Qujing ISR frequently observed enhancements in electron density in the ionospheric F region during the afternoon‐evening period. Figure 12 of Ding et al (), for example, revealed exactly the same feature that NmF 2 enhances when hmF 2 descends to lower altitudes. Thus, it is still an unsolved question on the relationship between the variations of NmF 2 and hmF 2; namely, whether the increase in NmF 2 can be related in general to a drop in hmF 2 or not.…”

Section: Introductionmentioning

confidence: 99%

New Features of the Enhancements in Electron Density at Low Latitudes

Zhang²,

et al. 2020

JGR Space Physics

Self Cite

In this study, we present some new features of the enhancements of electron density in the ionospheric F region at low latitudes. The peak parameters of the ionosphere were recorded by Sanya (109.6°E, 18.3°N) ionosonde and electron density profiles analyzed were measured by the Qujing (103.8°E, 25.6°N) incoherent scatter radar. The peak electron density of the F2 layer (NmF2) is found to be enhanced in the afternoon and sunset hours. Common features in the cases demonstrate that the NmF2 increases at low latitudes are characterized by a descent of the peak height (hmF2). Meanwhile, the electron density at Qujing shows an increase at the bottom of the ionosphere and a depression at topside altitudes. It is consistent with those of the ionosonde measurements at Sanya, for both the daytime and nighttime enhancements. Cross correlation analyses reveal a lag of NmF2 to hmF2 in the cases. After taking time shifts some events of the enhancements in NmF2 are still associated with a downwelling hmF2, confirming the processes which drive a lower hmF2 and a convergence of plasma flux may possibly bring about a rise in NmF2.

“…Ding ZH et al (2018b) presented some examples of the Qujing incoherent scatter radar (QJISR). The spectrum shape changes from a single hump to double humps with increasing altitude.…”

Section: Ionospheric Structures and Climatologymentioning

confidence: 99%

Recent ionospheric investigations in China (2018–2019)

Earth and Planetary Physics

Wan

2020

Key Points:Ionospheric observations have continuously accumulated with increasing GNSS receivers being installed q Studies of ionospheric climatology and space weather highlight new physical understanding q Study of ionospheric irregularities/scintillations reports interesting features q Abstract: Since the release of the 2018 National Report of China on ionospheric research ( Liu LB and Wan WX, 2018) to the Committee on Space Research (COSPAR), scientists from Mainland China have made many new fruitful investigations of various ionospheric-related issues. In this update report, we briefly introduce more than 130 recent reports ( [2018][2019]. The current report covers the following topics: ionospheric space weather, ionospheric structures and climatology, ionospheric dynamics and couplings, ionospheric irregularity and scintillation, modeling and data assimilation, and radio wave propagation in the ionosphere and sounding techniques. ΔV para (m/s) SYM-H (nT) V para (m/s) V para (m/s) ΔV para (m/s) Figure 2. (a) The SYM-H index on 13-17 July 2012. The blue line marks the storm onset (at 06:42 UT on 15 July); yellow and gray areas indicate the 24-hour storm-time and 24-hour quiet-time intervals. (b) The blue dots denote the storm-time equatorial field-aligned plasma drifts observed by C/NOFS with red curve representing median and red lines denoting upper and lower quartile values. (c) Same as panel (b), but for the 24-hour quiet time interval. (d) The difference between (b) and (c). (e-h) Same as panels (a-d), but for the case on 7-11 July 2012 where the 24-hour quiet and storm intervals start at 04:12 UT on 7 and 9 July, respectively, after Zhang R et al. (2018). Earth and Planetary Physics