Statistical Characteristics of the Local Proton Cyclotron Band Emissions Observed by the CSES

• Published in: Journal of geophysical research. Space physics 2022-11, Vol.127 (11), p.n/a
• Main Authors: Wang, Yalu, Zhima, Zeren, Wang, Xiao, Wu, Yingyan, Ouyang, Xin‐Yan, Hu, Yunpeng, Lu, Hengxin, Shen, Xuhui, Dong, Lei
• Format: Article
• Language: English
• Subjects: Algorithms; Bandwidths; Cyclotron frequency; Cyclotrons; Emissions; Ionosphere; Latitude; Protons; Summer; Upper ionosphere; Winter
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2022JA030860

We present observations on the local proton cyclotron band emissions (PCBEs), which is one type of hiss wave in the upper ionosphere, recorded by the China Seismo‐Electromagnetic Satellite (CSES). The PCBEs are characterized by narrow‐band electromagnetic emissions along the local proton cyclotron frequency (fcp ${f}_{\mathrm{c}\mathrm{p}}$), exhibiting a sharp cutoff effect. The lower cutoff frequency (fcut−low ${f}_{\mathrm{c}\mathrm{u}\mathrm{t}-\mathrm{l}\mathrm{o}\mathrm{w}}$) is closely along the local fcp ${f}_{\mathrm{c}\mathrm{p}}$, decreasing with magnetic latitude, while the upper cutoff frequency (fcut−up ${f}_{\mathrm{c}\mathrm{u}\mathrm{t}-\mathrm{u}\mathrm{p}}$) is diffuse and deviates from the local fcp ${f}_{\mathrm{c}\mathrm{p}}$. We developed an algorithm to automatically extract PCBEs from CSES's massive electromagnetic data and statistically examined their occurrence and bandwidth's dependence on location and season. The global morphology of PCBEs in 2019 shows that they primarily occur in the mid‐high magnetic latitude (approximately 20°–55°) dayside ionosphere, with the maximum occurrence happening around the South Atlantic Anomaly region. Their bandwidth shows a decreasing tendency with magnetic latitude and strong seasonal dependence, with a wider bandwidth in local winter and a narrower one in local summer. The ratio of fcut−low ${f}_{\mathrm{c}\mathrm{u}\mathrm{t}-\mathrm{l}\mathrm{o}\mathrm{w}}$ and fcp ${f}_{\mathrm{c}\mathrm{p}}$ also shows a seasonal dependence, with greater values in local summer and smaller values in local winter. This characteristic of fcut−low ${f}_{\mathrm{c}\mathrm{u}\mathrm{t}-\mathrm{l}\mathrm{o}\mathrm{w}}$ is similar to that of the H+‐He+ cutoff frequency (fcut−ion ${f}_{\mathrm{c}\mathrm{u}\mathrm{t}-\mathrm{i}\mathrm{o}\mathrm{n}}$). This study provides statistical characteristics of occurrence and the cutoff features of PCBEs based on the CSES operating in the upper ionosphere. Key Points The local proton cyclotron band emissions (PCBEs) are predominant on the dayside with a maximum occurrence around the South Atlantic Anomaly region The bandwidth tends to decrease with magnetic latitude and shows a strong seasonal dependence The local PCBEs exhibit a sharp cutoff effect due to the ion composition in the ionosphere