Characteristics of slant sporadic-E layers observed at low-latitudes

IF 3.2 3区地球科学 Q2 ASTRONOMY & ASTROPHYSICS

Advances in Space Research Pub Date : 2026-07-01 Epub Date: 2025-09-30 DOI:10.1016/j.asr.2025.09.090

Peter T. Muka, Marcio T.A.H. Muella, Fredson Conceição-Santos, Laysa C.A. Resende, Paulo R. Fagundes, Olufemi L. Ogunmola, Pedro A. Fontes, Valdir G. Pillat, Mariah Cesar, Rodolfo de Jesus

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Abstract

This study investigates the occurrence, characteristics, and formation mechanisms of slant sporadic-E layers (Es_s). The Es_s-type layers observed at the Brazilian low-latitude stations of Jataí (17.9°S, 51.7°W) and São José dos Campos (23.2°S, 45.8°W), are analyzed using ionosonde data recorded for four months (April, June, September, and December) of 2016. Parameters such as top frequency (ftEs), blanketing frequency (fbEs), and virtual height (h’Es) were scaled from ionograms to characterize the slant (Es_s) traces. The results show that Es_s-type layers predominantly occur at night, forming between 95 and 120 km altitudes, with monthly and local variations. Model simulations using meteor radar-derived winds revealed that strong and stable zonal wind shear are associated with increased Es_s-type layer activity. In addition, wavelet spectral analyses of ftEs and fbEs showed that tidal periodicities (diurnal, semidiurnal, terdiurnal, and quarterdiurnal) and their interactions with gravity waves seem to play fundamental roles in the formation of Es_s-type layers. A comparison of ΔF (ftEs-fbEs) during Es_s-type events confirmed the presence of strong plasma density gradients, supporting the hypothesis that the slanted traces in ionograms result mostly from oblique reflections in inhomogeneous Es layer structures. However, the appearance of slant Es traces may in some cases be related to an actual tilt of the layer. Other relevant aspects of the observations associated with the possible physical mechanisms behind the formation of Es_s-type layers at low latitudes are highlighted and discussed.

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低纬度观测到的倾斜散点e层特征

本文研究了斜散e层（Ess）的赋存、特征及形成机制。利用2016年4月、6月、9月和12月4个月的电离探空仪资料，对巴西Jataí低纬度站（17.9°S, 51.7°W）和 o jos dos Campos站（23.2°S, 45.8°W）观测到的ess型层进行了分析。参数，如最高频率（fte），覆盖频率（fbEs），和虚拟高度（h 'Es）从电离图缩放，以表征倾斜（Ess）走线。结果表明，s型层主要出现在夜间，形成于海拔95 ~ 120 km之间，具有月变化和局地变化。利用流星雷达衍生风的模式模拟显示，强而稳定的纬向风切变与less型层活动增加有关。此外，fte和fbEs的小波谱分析表明，潮汐周期（日、半日、日、四分之一日）及其与重力波的相互作用似乎在ess型层的形成中起着重要作用。在ess型事件中ΔF （fes - fbes）的比较证实了强等离子体密度梯度的存在，支持了电离图中的倾斜迹线主要是由非均匀Es层结构的斜反射引起的假设。然而，在某些情况下，倾斜的Es痕迹的出现可能与层的实际倾斜有关。强调并讨论了与低纬度s型层形成背后可能的物理机制有关的观测的其他有关方面。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Advances in Space Research 地学天文-地球科学综合

CiteScore

5.20

自引率

11.50%

发文量

800

审稿时长

5.8 months

期刊介绍： The COSPAR publication Advances in Space Research (ASR) is an open journal covering all areas of space research including: space studies of the Earth''s surface, meteorology, climate, the Earth-Moon system, planets and small bodies of the solar system, upper atmospheres, ionospheres and magnetospheres of the Earth and planets including reference atmospheres, space plasmas in the solar system, astrophysics from space, materials sciences in space, fundamental physics in space, space debris, space weather, Earth observations of space phenomena, etc. NB: Please note that manuscripts related to life sciences as related to space are no more accepted for submission to Advances in Space Research. Such manuscripts should now be submitted to the new COSPAR Journal Life Sciences in Space Research (LSSR). All submissions are reviewed by two scientists in the field. COSPAR is an interdisciplinary scientific organization concerned with the progress of space research on an international scale. Operating under the rules of ICSU, COSPAR ignores political considerations and considers all questions solely from the scientific viewpoint.