First Lidar Profiling of Meteoric Ca⁺ Ion Transport From ∼80 to 300 km in the Midlatitude Nighttime Ionosphere

Abstract

We report a world record of lidar profiling of metallic Ca+ ions up to 300 km in the midlatitude nighttime ionosphere during geomagnetic quiet time. Ca+ measurements (∼80–300 km) were made over Beijing (40.42°N, 116.02°E) with an Optical‐Parametric‐Oscillator‐based lidar from March 2020 through June 2021. Main Ca+ layers (80–100 km) persist through all nights, and high‐density sporadic Ca+ layers (∼100–120 km) frequently occur in summer. Thermosphere‐ionosphere Ca+ (TICa+) layers (∼110–300 km) are likely formed via Ca+ uplifting from these sporadic layers. The lidar observations capture the complete evolution of TICa+ layers from onset to ending, revealing intriguing features. Concurrent ionosonde measurements show strong sporadic E layers developed before TICa+ and spread F onset. Neutral winds can partially account for observed vertical transport but enhanced electric fields are required to explain the results. Such lidar observations promise new insights into E‐ and F‐region coupling and plasma inhomogeneities.

Multiple Ionospheric Descending Layers Over Arecibo

“…Notably, these IonDLs are observed during quiet geomagnetic conditions. And occurring range/starting altitudes are higher than any previous reports from ISR, sounding rocket, coherent radar, lidar, and rocket observations (Earle et al, 2000;Fujitaka & Tohmatsu, 1971, 1973Patra et al, 2002;Jiao et al, 2022). Predominant IonDLs reach the E region and/or the top of the E region from 350-400 km, which mostly crosses the discontinuity region of ∼170 km at twilight times.…”

“…Most of the earlier investigations reported the presence of IDLs up to 180 km (Christakis et al, 2009;Raizada et al, 2020;Earle et al, 2000;Fujitaka & Tohmatsu, 1973), and moreover, most of them are nighttime observations (Jiao et al, 2022). For example, Fujitaka and Tohmatsu (1973) stated morphology of the IDLs using the rocket observations that middle latitude IDLs usually observed after midnight at an altitude of 140 km.…”

“…Earle et al (2000) mentioned these IDLs form near 170 km since their data is altitudelimited to 170 km, and also, there is a discontinuity in the layering process around that altitude. At the altitudes of IDLs, a recent study by Jiao et al (2022) showed that TICa + (Thermosphere-Ionophere Ca + ) appear even beyond 170 km. Interestingly, these IDLslike layers were observed in Ca + lidar at Yanqing Station (40.42 o N, 116.02 o E) near Bei--3-manuscript submitted to JGR: Space Physics jing.…”

“…Similar layers were also observed over Arecibo using AO Ca + lidar (Raizada et al, 2020), but the altitudes were limited to ∼180 km. Jiao et al (2022) ruled out the long-range transport from low or high latitudes and hypothesized that regional vertical ion transport from the D-E to the F region occurs at the time of spread-F event by a combination of enhanced neutral wind electric field in the mid-latitude ionosphere.…”

“…Most of the earlier investigations on IDLs are mainly focused on the altitude range below 170 km (Earle et al, 2000;Fujitaka & Tohmatsu, 1971, 1973Patra et al, 2002;Dos Santos et al, 2019) until recently by Jiao et al (2022). From the same AO-ISR observations, IDLs were studied by Earle et al (2000) and suggested that gravity waves or local modulations of the large-scale background winds may be more significant in forming these IDLs.…”