Kyoto University · Physics and Astronomy
Professor Satoshi Andoh's research lab specializes in atmospheric and ionospheric sciences, focusing on the dynamics and variability of sporadic E (Es) layers in the Earth's ionosphere. The lab employs advanced three-dimensional numerical ionospheric models to investigate the roles of atmospheric tides, wind shears, electric fields, and neutral winds in shaping the formation, structure, and day-to-day variations of Es layers at mid- and low-latitudes. Their work bridges atmospheric physics and space weather, aiming to improve understanding and forecasting of ionospheric disturbances that affect radio communication and navigation systems. The lab is particularly known for pioneering 3D simulations that reproduce complex, sporadic, and multi-layered ionospheric phenomena.
Figures are computed from collected data and may differ slightly.
Abstract We present the first simulations that successfully reproduce the day-to-day variability of the mid-latitude sporadic E ( $$E_s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>E</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:math> ) layers. $$E_s$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>E</mml:mi><mml:mi>s</mml:mi></mml:msub></mml:math> layers appearing in the lower ionosphere have been extensively investigated to monitor and f
Abstract A regional numerical ionospheric model with neutral winds, corresponding to the Ground‐to‐topside model of Atmosphere and Ionosphere for Aeronomy model, was used to investigate the temporal evolution of 3‐D structures of metal ion layers (MILs) around Japan. The MILs that appear specifically in the ionospheric E region, called “sporadic E ,” display complicated multi‐layer structures and intense density variations. Although the wind shear theory elucidates the basic formation mechanism
Abstract To reveal mechanisms of day‐to‐day variations of the low‐latitude sporadic E (Es) layers, Es layer simulations were performed and compared to plasma layers observed by the Arecibo radar. Many studies have been conducted about the Es layers till now. However, few studies investigated the day‐to‐day variations of the Es layers especially at the low‐latitudes. Herein, for the first time, our numerical model generally succeeded in reproducing features of the day‐to‐day variations of the low
Abstract The present study aims to reveal horizontal sporadic E (Es) movements driven by atmospheric diurnal/semi-diurnal tides using a three-dimensional (3D) ionospheric model. Horizontal Es movements have been investigated since the mid-twentieth century, using a variety of 1D/2D observational techniques. However, there are no comprehensive studies that explain the different results asserted by the observations. Herein, we performed 3D Es simulations at mid- and low-latitudes. This is the firs
Abstract This study investigates the effects of the electric fields (E‐fields) on day‐to‐day variations in geomagnetic mid‐latitude sporadic E layers (EsLs) using a numerical ionospheric model. It is widely accepted that geomagnetic mid‐latitude EsL dynamics depend largely on wind shear variations. In contrast, E‐field effects on geomagnetic mid‐latitude EsLs have not been investigated extensively and are still little known. Previous observations have reported that E‐fields change EsL heights by
Abstract This study provides a physical mechanism for the temporary intensification of wintertime sporadic E layers (EsLs) in 2009. It is widely accepted that vertical wind shears control EsL formations. EsL intensity is minimal in winter, partially because of the weakened vertical wind shears. Despite the wintertime minimum EsL intensity, temporary intensifications of EsLs occurred for 10–30 days in some winters, the cause of which remains unclear. In this study, we conducted month-long EsL sim
Abstract This study examines the role of winds in wintertime sporadic E layer intensification (WEsLI) in 2009 from a global viewpoint. Previous studies showed that sporadic E layer (EsL) intensity had increased for 20–30 days in some winters, although intense EsLs do not form generally in winter. A recent study found that vertical ion convergence (VIC) driven by intensified migrating semidiurnal (SW2) tides caused WEsLI at middle latitudes in 2009. However, no studies have investigated the globa
Data file for the paper 'Temporal evolution of three-dimensional structures of metal ion layer around Japan simulated by a mid-latitude ionospheric model'
The temporal evolution of the three-dimensional metal ion flow (MIF) is crucial for polar sporadic E layer dynamics. Yet, until now it has not been studied in detail. Here, we present a new ionospheric model for metal ion dynamics, which incorporates electric fields and winds from a whole atmospheric model. We revealed the time-dependent three-dimensional MIFs in the polar ionosphere, driven by two-cell convective electric fields. The simulated MIFs closely matched observations reported in previ
Data file for the paper 'Temporal evolution of three-dimensional structures of metal ion layer around Japan simulated by a mid-latitude ionospheric model'
Abstract We investigate the cause of the spatial distribution of sporadic E (Es) layer occurrences in the austral summer Southern Hemisphere using a numerical model that incorporates metal ion dynamics. Previous studies have attributed longitudinal variations in Es occurrence (EsO) distributions to geomagnetic field distributions, particularly suggesting that high magnetic inclination causes a significant reduction in EsO near Southern Africa. In this study, we perform Es layer simulations for l
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