Initial Ionospheric Ion Line Results and Evaluation by Sanya Incoherent Scatter Radar (SYISR). Issue 9 (16th September 2022) - Hao, Honglian
Abstract: A new incoherent scatter radar (ISR) has recently been dedicated at Sanya (SYISR), China (geographic 18.34°N and 109.62°E) to detect the low‐latitude ionospheric plasma by conducting continuous operation and electronic beam steering on a pulse‐to‐pulse basis. This paper provides an overview of the processing procedure of SYISR ion line data and presents some preliminary observational results under various transmitting signal schemes and different working modes, such as the zenith‐directed mode and meridional and zonal scanning modes, with comparison to the international reference ionosphere model (IRI‐2016), ionosonde and Ionospheric Connections Explorer (ICON) satellite measurements. The diurnal and altitude versus latitude variation characteristics of electron density ( N e ), electron temperature ( T e ), and ion temperature ( T i ) are in accordance with those of other ISR measurements in mid‐low latitudes, and IRI shows some discrepancies with SYISR observations, including the sunrise and sunset enhancement in SYISR_ T i and the overestimated IRI_ T e . The comparison between the daytime SYISR_ T i and ICON_ T i shows good consistency based on 31 observational samples. The measurement of line‐of‐sight velocity ( V i ) for long pulse can reveal the properties of the medium scale traveling ionospheric disturbances manifesting the radar's potential to study the mesoscale ionospheric variation in the Sanya area. The derived vector velocities with a better measurement accuracy during the day are generally in line with ionospheric plasma physics. The results show that SYISR can obtain continuous ionospheric parameters through multi‐beam scanning measurements at ∼700 km horizontal scale, which provides important information for studying the atmosphere‐ionosphere‐magnetosphere coupling and ionospheric scintillation at low latitudes in East Asia. Plain Language Summary: China's first phased‐array incoherent scatter radar was completed in 2021 in Sanya, which is called SYISR. SYISR aims to investigate fundamental scientific problems in the ionosphere, including atmosphere‐ionosphere‐magnetosphere coupling, regional ionospheric properties and ionospheric irregularities in southern China. SYISR can directly measure electron density, electron and ion temperature, and drift velocity of the ionospheric plasma and can be used to indirectly obtain the temperature of the neutral atmosphere, wind field and irregularity information. This paper describes in detail the data processing from the IQ signal to the derived ionospheric parameters for SYISR. Ionospheric experiments in various scanning modes have been performed, mainly including a single beam in zenith‐directed mode and multiple beams in meridian and zonal scanning modes, and the obtained results are evaluated. These experimental results are evaluated through comparison with the IRI‐2016 model, digital ionosonde and Ionospheric Connections Explorer satellite. The comparison results indicate that SYISR is able to provide reliable, unique, and important ionospheric information for the study of ionospheric science at low latitudes in East Asia. Key Points: Sanya incoherent scatter radar (SYISR) is a new phased array system dedicated to the ionospheric observations at low latitudes in Asia sector SYISR is operational, providing high‐quality ionospheric measurements in multiple radar scanning modes and radio pulse schemes modes Data processing procedures and initial ion‐line results using typical experiment modes are reported