Neutral Wind Research Articles

On the Spatial Structure and Zonal Drift of Low Latitude E Region Irregularity Patches Over Hainan

AbstractAll‐sky radar measurements provide a unique capability to resolve the spatial structure of E region irregularities over a large zonal region. With the all‐sky radar interferometry observations at Ledong (18.4°N, 109.0°E) in Hainan, China, the spatial structure and zonal drift of low latitude E region field‐aligned irregularities (FAIs) over a large region are statistically investigated for the first time. It is revealed that the E region FAIs, including both the continuous and quasi‐periodic (QP) types shown in radar range‐time‐intensity maps, occurred most frequently in summer. The continuous type was observed being generated locally without obvious zonal drift. The QP type generally covered ∼40–500 km zonally, and consisted of up to 9 (peaking at 3–4) FAI patches separated by ∼20–130 km (peaking at ∼60 km). The spatially separated FAI patches predominantly drifted westward at the speed ∼50–200 m/s. Besides the Kelvin‐Helmholtz instability, gravity waves were surmised to be a major source for causing the spatial structures of low latitude QP type E region FAIs. Neutral wind was suggested to play an important role for their zonal drifts.

Driver of the Positive Ionospheric Storm over the South American Sector during 4 November 2021 Geomagnetic Storm

During geomagnetic storms, ionospheric storms can be driven by several mechanisms. Observations performed using ground- and space-based instruments were used to reveal the driver of the positive ionospheric storm over the South American sector during the 4 November 2021 geomagnetic storm. The positive storm appeared from 10:30 UT to 18:00 UT and covered the region from 40°S to 20°N. The maximum magnitudes of TEC (Total Electron Content) enhancement and relative TEC enhancement were about 20 TECU and 100%, respectively. Defense Meteorological Satellite Program (DMSP) also observed a significant electron density increase over South America and the eastern Pacific Ocean. In the meantime, about 50% ∑O/N2 enhancement was observed by the Global-scale Observations of the Limb and Disk (GOLD) satellite at low latitudes. Ionosonde observations (AS00Q and CAJ2M) registered an ~80 km uplift in F2 peak height (HmF2) and a prominent F2 peak electron density (NmF2) increase ~3 h after the uplift. A prominent enhancement in the cross-polar cap potential (CPCP) in the southern hemisphere was also observed by Super Dual Auroral Radar Network (SuperDARN) one hour earlier than the HmF2 uplift. Measurements of the Ionospheric Connection Explorer satellite (ICON) showed that the outward E×B drift was enhanced significantly and that the horizontal ion drift was poleward. According to the ICON ion drift observations, the HmF2 uplift was caused by an electric field rather than equatorward neutral wind. We propose that the enhanced eastward electric field dominated the positive ionospheric storm and that the thermospheric composition variation may have also contributed.

Statistical relation of traveling ionospheric disturbances with neutral wind and disturbances in the stratosphere

Using the representative statistics on traveling ionospheric disturbances (TIDs) obtained by Yekaterinburg and Magadan radars, we have shown that distributions of TIDs and average TID velocities by azimuths and local time agree well with the hypothesis on internal gravity wave (IGW) filtering by the neutral wind. We have examined the influence of significant winter sudden stratospheric warmings on IGW in the ionosphere. A method has been proposed for estimating zonal and meridional neutral wind velocities from MSTID parameters. The method is universal and allows us to estimate the zonal and meridional neutral wind velocities from the statistics on MSTID 2D phase velocity vector obtained by any tool. There is a large amount of data from which MSTID 2D phase velocity vector (as opposed to the 3D phase velocity vector) can be derived, including maps of TEC disturbances and all-sky camera images. This method may therefore be useful in developing and improving neutral wind models.

Статистическая связь перемещающихся ионосферных возмущений с нейтральным ветром и возмущениями в стратосфере

Using the representative statistics on traveling ionospheric disturbances (TIDs) obtained by Yekaterinburg and Magadan radars, we have shown that distributions of TIDs and average TID velocities by azimuths and local time agree well with the hypothesis on internal gravity wave (IGW) filtering by the neutral wind. We have examined the influence of significant winter sudden stratospheric warmings on IGW in the ionosphere. A method has been proposed for estimating zonal and meridional neutral wind velocities from MSTID parameters. The method is universal and allows us to estimate the zonal and meridional neutral wind velocities from the statistics on MSTID 2D phase velocity vector obtained by any tool. There is a large amount of data from which MSTID 2D phase velocity vector (as opposed to the 3D phase velocity vector) can be derived, including maps of TEC disturbances and all-sky camera images. This method may therefore be useful in developing and improving neutral wind models.

The future of auroral E-region plasma turbulence research

The heating caused by ionospheric E-region plasma turbulence has documented global implications for the energy transfer from space into the terrestrial atmosphere. Traveling atmospheric disturbances, neutral wind motion, energy deposition rates, and ionospheric conductance have all been shown to be potentially affected by turbulent plasma heating. Therefore it is proposed to enhance and expand existing ionospheric radar capabilities and fund research into E-region plasma turbulence so that it is possible to more accurately quantify the solar-terrestrial energy budget and study phenomena related to E-region plasma turbulence. The proposed research funding includes the development of models to accurately predict and model the E-region plasma turbulence using particle-in-cell analysis, fluid-based analysis, and hybrid combinations of the two. This review provides an expanded and more detailed description of the past, present, and future of auroral E-region plasma turbulence research compared to the summary report submitted to the National Academy of Sciences Decadal Survey for Solar and Space Physics (Heliophysics) 2024–2033 (Huyghebaert et al., 2022a).

Explaining Ionospheric Ion Upflow in the Subauroral Polarization Streams

Ionospheric ion upflow is an important process for magnetosphere-ionosphere coupling via O+ source for the magnetosphere. This process occurs frequently in the subauroral polarization stream (SAPS) region where the SAPS-enhanced ion-neutral frictional heating tends to push ions upward because of enhanced upward pressure gradient force. However, the SAPS-induced neutral wind transport by ion-neutral friction may also play an important role in triggering ion upflow, which has been rarely studied. In this work, the thermosphere-ionosphere-electrodynamics general circulation model (TIEGCM) with/without an empirical SAPS model has been employed to investigate the impacts of SAPS on ion upflow in the topside ionosphere. Our results separate different transport processes in the ion continuity equation, showing that SAPS can accelerate upward ambipolar diffusion along its channel because of ion-neutral frictional heating, but SAPS-induced horizontal neutral wind may have a comparable or even larger contribution to vertical ion drift when SAPS are fully developed. In addition, the neutral wind can induce both upward and downward ion drift in the SAPS region, depending on the direction of the neutral wind and the local geomagnetic declination and inclination.

Variations in the Equatorial Ionospheric F Region Current during the 2022 Tonga Volcanic Eruption

In this work, the temporal variations in the ionospheric F region current (FRC) during the 2022 volcanic eruption in Tonga are reported for the first time. The FRC increased and underwent several polarity reversals following the eruption, as observed by the dual Swarm satellites. By combining neutral wind observations derived from the Ionospheric Connection Explorer (ICON) satellite, we attempt to reveal the potential physical mechanisms responsible for these variations. The ICON and Swarm satellites were located at almost the same distance from the epicenter of the volcanic wave, thus providing a good opportunity for analyzing coordinated observations. The F-layer neutral wind data reflect eastward and westward fluctuations that are basically consistent with the polarity reversals identified in the FRC. The E-layer neutral wind also exhibits polarity reversals that affect the equatorial ionosphere electron density anomaly. These results show that the atmospheric fluctuations caused by the analyzed volcanic eruption affected the wind pattern distribution in the E-F region, thus further affecting the spatial distribution of the FRC and electron density in the F layer.

INM-IM: INM RAS Earth ionosphere F region dynamical model

Abstract A new INM RAS global dynamical model of Earth’s ionosphere F region (100–500 km), which takes into account plasma-chemical processes, ambipolar diffusion, and advective ion transport due to electromagnetic drifts and neutral wind is presented. The model includes parameterizations of polar electric fields induced by magnetospheric convection and simplified equatorial drifts considerations. The focus of the paper is directed on the description of specific methods developed and utilized in the ionospheric model. Key processes responsible for the formation of global ionospheric features are outlined and their representation in the model is evaluated. The main global ionospheric characteristic features, such as seasonal and diurnal cycles, the equatorial ionization anomaly (EIA), polar ionization caps and the main trough have been adequately reproduced based on this model.

ARIES ST Radar: The First Central Himalayan Wind Profiler

Recently, a 206.5[Formula: see text]MHz Stratosphere Troposphere (ST) Radar system was successfully installed and made operationalized at Aryabhatta Research Institute of Observational Sciences (ARIES) (29.4N, 79.2E, 1793[Formula: see text]m amsl), Nainital, India. It is the first such unique observational facility located in the central Himalayan region and will play an important role in understanding the meteorological conditions of the region that has a vital role in atmospheric studies in South Asia. The entire ST radar system is indigenously built and installed in a compact 30[Formula: see text][Formula: see text][Formula: see text]m two-storey building, making maximum use of the available space in the hilly terrain. A metal fence of 3.5–4[Formula: see text]m height was designed and installed along the perimeter of the array to attenuate the clutter returns from the nearby mountains with the shielding efficiency 22–25[Formula: see text]dB. Since its operation, the radar has obtained useful data of neutral atmosphere, precipitation, convection, and hailstorm events for scientific research. The technical details of different sub-systems, radar integration and calibration methodology are presented here. A dedicated off-line GUI based data processing tool has been developed and is being used for the data analysis. A comparison of wind components derived from ARIES ST Radar with collocated GPS-radiosonde observations indicates a good agreement with correlation coefficients for zonal (0.92), meridional (0.76), wind speed (0.86), and wind direction (0.7). The change in wind patterns is demonstrated up to a height of about 31[Formula: see text]km amsl and the tropopause was marked to be at 16–17[Formula: see text]km on 2020 June 20. A dramatic reversal of winds from westerly (below the tropopause) to easterly (above the tropopause) was also observed. ARIES ST Radar could capture the signature of the precipitation in addition to neutral air in the same Doppler spectrum and the height of the starting point of precipitation is identified to be [Formula: see text][Formula: see text]km. This ability to detect atmospheric scattering from both neutral wind (Bragg) and precipitation (Rayleigh) in the same spectrum makes the 200[Formula: see text]MHz band radar a unique instrument in the wind profiler application for atmospheric research.

Modeling Solar Eclipses at Extreme Ultra Violet Wavelengths and the Effects of Nonuniform Eclipse Shadow on the Ionosphere‐Thermosphere System

AbstractThe impacts of solar eclipses on the ionosphere‐thermosphere system particularly the composition, density, and transport are studied using numerical simulation and subsequent model‐data comparison. We introduce a newly developed model of a solar eclipse mask (shadow) at extreme ultraviolet (EUV) wavelengths—PyEclipse—that computes the corresponding shadowing as a function of space, time, and wavelength of the input solar image. The current model includes interfaces for Solar Dynamics Observatory and Geostationary Operational Environmental Satellites EUV telescopes providing solar images at nine different wavelengths. We show the significance of the EUV eclipse shadow spatial variability and that it varies significantly with wavelength owing to the highly variable solar coronal emissions. We demonstrate geometrical differences between the EUV eclipse shadow compared to a geometrically symmetric simplification revealing changes in occultation vary ±20%. The EUV eclipse mask is validated with in situ solar flux measurements by the PRoject for Onboard Autonomy 2/Large Yield Radiometer instrument suite showing the model captures the morphology and amplitudes of transient variability while the modeled gradients are slower. The effects of spatially EUV eclipse masks are investigated with Global Ionosphere Thermosphere Model for the 21 August 2017 eclipse. The results reveal that the modeled EUV eclipse mask, in comparison with the geometrically symmetric approximation, causes changes in the Total Electron Content in order of ±20%, 5%–20% in F‐region plasma drift, and 20%–30% in F‐region neutral winds.

Multi‐Scale Geomagnetic Forcing Derived From High‐Resolution Observations and Their Impacts on the Upper Atmosphere

AbstractTechniques developed in the past few years enable the derivation of high‐resolution regional ion convection and particle precipitation patterns from the Super Dual Auroral Radar Network (SuperDARN) and Time History of Events and Macroscale Interactions during Substorms All‐Sky Imager (ASI) observations, respectively. For the first time in this study, a global ionosphere‐thermosphere model (GITM) is driven by such high‐resolution patterns to simulate the I‐T response to the multi‐scale geomagnetic forcing during a real event. Specifically, GITM simulations have been conducted for the 26 March 2014 event with different ways to specify the high‐latitude forcing, including empirical models, high‐resolution SuperDARN convection patterns, and high‐resolution ASI particle precipitation maps. Multi‐scale ion convection forcing estimated from high‐resolution SuperDARN observations is found to have a very strong meso‐scale component. Multi‐scale convection forcing increases the regional Joule heating (integrated over the high‐resolution SuperDARN observation domain) by ∼30% on average, which is mostly contributed by the meso‐scale component. Meso‐scale electron precipitation derived from ASI measurements contributes on average about 30% to the total electron energy flux, and its impact on the I‐T system is comparable to the meso‐scale convection forcing estimated from SuperDARN observations. Both meso‐scale convection and precipitation forcing are found to enhance ionospheric and thermospheric disturbances with prominent structures and magnitudes of a few tens of meters per second in the horizontal neutral winds at 270 km and a few percent in the neutral density at 400 km through comparisons between simulations driven by the original and smoothed high‐resolution forcing patterns.

Investigation of the ΣO/N2 Depletion With Latitudinally Tilted Equatorward Boundary Observed by GOLD During the Geomagnetic Storm on April 20, 2020

AbstractA long‐lived (>10 hr) O/N2 column density ratio (∑O/N2) depletion at middle latitudes was observed by the Global‐scale Observations of the Limb and Disk (GOLD) during the 20 April 2020 geomagnetic storm. The observed ∑O/N2 depletion tilts latitudinally at equatorward boundary with the lowest latitude of ∼20°N at ∼75°W, and changes orientation near 75°W, with a north‐westward tilt to the west of ∼75W and a north‐eastward tilt to the east of ∼75W. The National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model shows the similar ∑O/N2 depletion patterns and magnitudes, but the longitudes with the most equatorward were ∼100°W and moved westward from ∼100°W to ∼140°W during the storm recovery period. Horizontal winds play major role in forming this middle‐latitude ∑O/N2 depletion structure. The strongest equatorward winds in the longitude sector near the magnetic pole resulted in the most equatorward expansion of all longitudes, generating the depletion with latitudinally tilted equatorward boundary. In addition, the high‐latitude westward zonal wind and the middle‐latitude eastward zonal wind maintained the long existence of this depletion in the GOLD Field of View. The further analysis on neutral winds shows that storm‐time meridional winds at middle latitudes in the mid‐low thermosphere are mainly dominated by pressure gradient force, while zonal winds are determined primarily by horizontal momentum advection.

Energy Deposition by Mesoscale High‐Latitude Electric Fields Into the Thermosphere During the 26 October 2019 Geomagnetic Storm

AbstractMesoscale high‐latitude electric fields are known to deposit energy into the ionospheric and thermospheric system, yet the energy deposition process is not fully understood. We conduct a case study to quantify the energy deposition from mesoscale high‐latitude electric fields to the thermosphere. For the investigation, we obtain the high‐latitude electric field with mesoscale variabilities from Poker Flat Incoherent Scatter Radar measurements during a moderate geomagnetic storm, providing the driver for the Global Ionosphere and Thermosphere Model (GITM) via the High‐latitude Input for Mesoscale Electrodynamics framework. The HIME‐GITM simulation is compared with GITM simulations driven by the large‐scale electric field from the Weimer model. Our modeling results indicate that the mesoscale electric field modifies the thermospheric energy budget primarily through enhancing the Joule heating. Specifically, in the local high‐latitude region of interest, the mesoscale electric field enhances the Joule heating by up to five times. The resulting neutral temperature enhancement can reach up to 50 K above 200 km altitude. Significant increase in the neutral density above 250 km altitude and in the neutral wind speed are found in the local region as well, lagging a few minutes after the Joule heating enhancement. We demonstrate that the energy deposited by the mesoscale electric field transfers primarily to the gravitational potential energy in the thermosphere.

On the Onset Time and Background Ionospheric Conditions of Postsunset Equatorial Plasma Bubble

AbstractOnset time and conditions of the postsunset equatorial plasma bubble (EPB) observed by the Gadanki Ionospheric Radar Interferometer are presented and discussed in the light of collocated digisonde observations of background ionosphere. Observations show two important findings: (a) onset time of EPB is linked with the sunset terminator and it varies between the low latitude E region sunset and apex F region sunset with a tendency of EPB onset to be close to low latitude E region sunset, and (b) higher height of the bottomside F layer (by 50–60 km) and vertical plasma drift (by 10–30 m s−1) observed over Gadanki are found to be associated with the EPBs growing in a narrow longitude zone of ±1° centered on Gadanki than those outside this zone. The early onset of EPB coinciding with the low latitude E region sunset is attributed to the early predominance of the F region dynamo leading to prereversal enhancement (PRE) of zonal electric field, consistent with theoretical expectation. Delay in the onset of EPB is attributed to the effect of flux tube integrated Pedersen conductivity owing to low latitude sporadic E activity and the F region meridional neutral wind that could change the F region plasma density along the flux tube through field‐aligned movement of plasma. Observations also show that ionosonde observations from a single location cannot be used to predict the growth of EPB at other location, including those close to the station but away from the station by about 120 km.

Ionospheric response during Tropical Cyclones - A Brief Review on Amphan and Nisarga

Here, we explore the different characteristics of a possible coupling between tropospheric and ionospheric activities during the impact of tropical cyclones (TC) like Amphan and Nisarga in the Indian subcontinent. We have analyzed the effect of TCs Amphan and Nisarga on the low latitude ionosphere using the measurements from several IGS stations around India and a GPS + NavIC station in Indore, India. For the first time, this study assesses the impact of tropical cyclones on the equatorial ionosphere using both GPS and NavIC. After the landfall of TC Amphan, the VTEC analysis shows a significant drop from nominal values in both NavIC as well in GPS by 5.1 TECU and 3.6 TECU, respectively. In contrast to TC Amphan, Nisarga showed a rise in VTEC which ranged from 0.9 TECU in GPS to 1.7 - 5 TECU in NavIC satellites except for PRN6. The paper examines Outgoing Longwave Radiation as a proxy to the convective activity which may be responsible for the ionospheric variation through the generation of gravity waves. In addition, the horizontal neutral wind observations at the location of TC landfall confirm the presence of ionospheric disturbances. VTEC perturbation analysis using a band-pass filter reveals a variation in differential TEC values between ±0.4 and ±0.8 based on the IGS station measurements. This indicates that the gravity wave is one of the responsible mechanisms for the lower–upper atmospheric coupling during both cyclones.

Multi-instrument observations of the Pajala fireball: Origin, characteristics, and atmospheric implications

Meteor observations provide information about Solar System constituents and their influx onto Earth, their interaction processes in the atmosphere, as well as the neutral dynamics of the upper atmosphere. This study presents optical, radar, and infrasound measurements of a daytime fireball that occurred on 4 December 2020 at 13:30 UTC over Northeast Sweden. The fireball was recorded with two video cameras, allowing a trajectory determination to be made. The orbital parameters are compatible with the Northern Taurid meteor shower. The dynamic mass estimate based on the optical trajectory was found to be 0.6–1.7 kg, but this estimate can greatly vary from the true entry mass significantly due to the assumptions made. The meteor trail plasma was observed with an ionosonde as a sporadic E-like ionogram trace that lasted for 30 min. Infrasound emissions were detected at two sites, having propagation times consistent with a source location at an altitude of 80–90 km. Two VHF specular meteor radars observed a 6 minute long non-specular range spread trail echo as well as a faint head echo. Combined interferometric range-Doppler analysis of the meteor trail echoes at the two radars, allowed estimation of the mesospheric horizontal wind altitude profile, as well as tracking of the gradual deformation of the trail over time due to a prevailing neutral wind shear. This combined analysis indicates that the radar measurements of long-lived non-specular range-spread meteor trails produced by larger meteoroids can be used to measure the meteor radiant by observing the line traveled by the meteor. Furthermore, a multistatic meteor radar observation of these types of events can be used to estimate mesospheric neutral wind altitude profiles.

Hemispherically Asymmetric Evolution of Nighttime Ionospheric Equatorial Ionization Anomaly in the American Longitude Sector

AbstractThe Global‐scale Observation of Limb and Disk (GOLD) mission observed distinct post‐sunset, hemispherically asymmetric evolution of the equatorial ionization anomaly between 40° and 50°W on 19 November 2018, with the southern crest shifting poleward but the northern crest remaining in the same latitude region. The Whole Atmosphere Community Climate Model‐eXtended captured this phenomenon. Diagnostic analysis revealed that this asymmetric evolution was due to the hemispheric asymmetry in plasma transport by E × B drifts and neutral winds. In the Northern hemisphere, northward neutral wind transport dominated around sunset (20 UT near 45°W), causing the crest to be at lower altitudes and decay faster. After pre‐reversal enhancement (PRE) occurred at 20 UT in the northern hemisphere, E × B and neutral wind transport largely balanced each other, and the crest remained in the same latitude region. In the southern hemisphere EIA crest, PRE occurred around 1 hr later than the one in the north. The northward neutral wind transported the plasma to higher altitudes with less recombination. E × B transport augmented the neutral wind transport after 21 UT, lifting and pushing the crest poleward. The magnetic field configuration (large declination) and the resultant occurrence time difference in PRE between 40°W and 50°W not only play critical roles in the asymmetric evolution of the two crests, but also makes it possible for this phenomenon to be observed in the GOLD field‐of‐view.

First Results on Characteristics of Nighttime MSTIDs Observed Over South Africa: Influence of Thermospheric Wind and Sporadic E

AbstractThis paper reports the climatology of medium‐scale traveling ionospheric disturbances (MSTIDs) observed between September 2018 and August 2019 in the nighttime redline airglow intensity measurements from an all‐sky imager located in Sutherland, South Africa (32.4°S, 20.8°E; magnetic latitude: 40.7°S). The nighttime MSTIDs appeared as either single or multiple dark bands, commenced mostly before midnight, and predominantly occurred during the southern winter solstice. They primarily propagated westward with speeds of 31–127 m/s. The periods and wavelengths of the multi‐band MSTIDs were in the ranges of 26–155 min and 134–578 km, respectively, while the temporal and spatial scales of the single band MSTIDs were 11–30 min and 43–143 km, respectively. Analysis of neutral wind measurements from a co‐located Fabry‐Perot interferometer showed that the thermospheric wind was mostly northeastward in the evenings of MSTID occurrence and that the favored westward propagation of the MSTIDs was the least restricted propagation direction by the background wind. Based on data from nearby ionosondes, the MSTIDs were mostly accompanied by sporadic E and spread‐F structures. From the seasonal occurrences of MSTIDs and sporadic E as well as the MSTID propagation and prevalent wind directions, it is concluded that Perkins instability is the most likely source of the majority of the observed nighttime MSTIDs, while the remainder may be seeded by gravity waves.

The Two‐Dimensional and Three‐Dimensional Structures Concerning the Traveling Ionospheric Disturbances Over Japan Caused by Typhoon Faxai

AbstractThe two‐dimensional concentric traveling ionospheric disturbances (TIDs) over Japan on the landfall day of Typhoon Faxai in 2019 were detected in total electron content by the ground‐based Global Navigation Satellite System observations. They propagated in the radial direction away from the typhoon eye with a horizontal velocity of ∼190 m/s, a period of ∼24 min, and a horizontal wavelength of ∼180 km. Then, we systematically investigated the corresponding three‐dimensional ionospheric responses for the first time. Remarkable wavelike structures of ionospheric electron density (Ne) and inverted conic‐like structures concerning the disturbed Ne (dNe) were visualized in the F region. Furthermore, the descending phase progression of dNe with increasing time was detected at 220–550 km altitudes, which powerfully revealed that the typhoon‐related TIDs were dominated by the upward atmospheric gravity waves (AGWs) propagating from the troposphere into the ionospheric F2 layer. By analyzing the spatial and temporal evolutions of Ne and dNe, we postulated that the transport process of neutral wind fluctuations associated with the upward AGWs were likely responsible for generating TIDs during Typhoon Faxai. In the end, the background wind velocity was estimated based on the recovered vertical wavelength of ∼460 km and the dispersion equation of AGWs. Our results also demonstrated that the weak background wind condition is essential for gravity waves propagating in the ionosphere.

Occurrence and Characteristics of Traveling Ionospheric Disturbances in the Antarctic Peninsula Region

AbstractA statistical picture of the occurrence and characteristics of Traveling Ionospheric Disturbances (TIDs) over the Antarctic Peninsula is established using Global Navigation Satellite System Total Electron Content and High Frequency sounding observations. The measured parameters of the majority of the disturbances allow classifying them as medium scale TIDs (MSTIDs). Overall, the observed climatology of ionospheric disturbances in the Antarctic Peninsula region varies significantly with the season and makes it possible to differentiate two major types of the disturbances: winter daytime and summer nighttime, based on their occurrence periods and characteristics. During the Antarctic summer period, the disturbances are present mainly during the nighttime and morning hours, when the background plasma density is at maximum (due to Weddell Sea Anomaly). These disturbances predominantly propagate northwestward and their occurrence probability is well correlated with the sporadic E layer observations, suggesting that these are electrified MSTIDs. During the winter, the TID events are almost exclusively observed during the daytime. The propagation direction of the disturbances during the daytime shows a strong correlation with the background neutral wind direction in the thermosphere. A possible mechanism for this effect is wind filtering of the Atmospheric Gravity Waves originating in the troposphere, which indicates that their source is in the lower atmosphere. The periods of the TIDs also significantly differ between the seasons. Wintertime TIDs have noticeably shorter periods (10–50 min) than those observed during other parts of the year (30–140 min), which also likely reflects the fact that the two types of TIDs are generated by different physical mechanisms.