We describe an upgrade of the HIgh Altitude Mechanistic general Circulation Model (HIAMCM) regarding 1) a new Dynamic Smagorinsky Model (DSM) for the parameterization of non-resolved scales and 2) the explicit computation of the major constituents. The DSM probes the smallest resolved scales to specify subgrid-scale viscosities, heat conduction coefficients, and diffusivities in a self-consistent fashion. The upgraded HIAMCM produces reasonable summer-to-winter-pole circulations in the upper mesosphere and in the thermosphere, as well as reversed circulation cells in between. The zonal-mean gravity wave (GW) drag reverses from the mesosphere and to the lower thermosphere in accordance with multi-step vertical coupling (MSVC). Interhemispheric asymmetries are explained via MSVC combined with interhemispheric coupling. In the winter (summer) thermosphere, the average dynamic heating (cooling) due to the residual circulation is substantial. The vertical heat flux by large-scale waves above about 150 km at low to middle latitudes is upward, which is consistent with the generation of tidal wave energy by radiative heating. The vertical heat flux due to gravity waves is downward, as expected. The constituent transport induces additional heating (cooling) in the winter (summer) upper thermosphere via the material time derivative of the heat capacity. At F region altitudes from middle to high latitudes, the strongest GW amplitudes during wintertime (summertime) are found on the dayside (nightside). These asymmetries are consistent with MSVC and the seasonal variation of the diurnal tide.

The composition, structure, and dynamics of the lower thermosphere (E- and F-region) has been of interest since the early days of radio communication. Bouncing HF signals off the ionosphere in the F-region ($300-400$ km) allowed long-range communication. Traveling ionospheric disturbances (TIDs) were first noticed in the HF signals bouncing off of the higher F-region ionization and are generally believed to be caused by atmospheric gravity waves perturbing the background structure.

Day-to-day variability in the Arctic winter thermosphere is driven, in part, by weather in the middle and lower atmosphere. The research presented here investigates the link between day-to-day stratospheric conditions, and local I-T variability over Alaska during the 2018-2019 Arctic winter. This work uses 4.3-mu m brightness temperature perturbation variances from the Atmospheric Infrared Sounder (AIRS) to quantify GW activity in the stratosphere, temperature perturbations from the High Altitude Mechanistic general Circulation Model (HIAMCM) to infer GW activity in the thermosphere, and Incoherent Scatter Radar electron density measurements for Medium Scale Traveling Ionospheric Disturbances (MSTID) activity in the ionosphere. We find that GW activity in the stratosphere and thermosphere, and MSTID activity in the ionosphere were suppressed during the 2018-2019 sudden stratospheric warming. These MSTID observations are in good agreement with HIAMCM thermospheric GW activity output. MSTID activity over Alaska is linked to stratospheric GW activity over Europe and NE Russia at different times during the season, highlighting the importance of cross-polar GW propagation. MSTID amplitudes over Alaska are also positively correlated with polar vortex strength and stratospheric wind speeds over Alaska at 50 km. These results support the conclusion that the I-T region is strongly coupled to the lower atmosphere through GW interactions with the polar vortex and their subsequent cross-polar propagation. While the importance of lower atmospheric drivers has previously been shown at mid-latitudes, this research emphasizes the importance of the polar vortex and lower atmospheric GW coupling in driving MSTID and thermospheric GW variability at high latitudes.

In Vadas et al. (2024, ), we modeled the atmospheric gravity waves (GWs) during 11-14 January 2016 using the HIAMCM, and found that the polar vortex jet generates medium to large-scale, higher-order GWs in the thermosphere. In this paper, we model the traveling ionospheric disturbances (TIDs) generated by these GWs using the HIAMCM-SAMI3 and compare with ionospheric observations from ground-based Global Navigation Satellite System (GNSS) receivers, Incoherent Scatter Radars (ISR) and the Super Dual Auroral Radar Network (SuperDARN). We find that medium to large-scale TIDs are generated worldwide by the higher-order GWs from this event. Many of the TIDs over Europe and Asia have concentric ring/arc-like structure, and most of those over North/South America have planar wave structure and occur during the daytime. Those over North/South America propagate southward and are generated by higher-order GWs from Europe/Asia which propagate over the Arctic. These latter TIDs can be misidentified as arising from geomagnetic forcing. We find that the higher-order GWs that propagate to Africa and Brazil from Europe may aid in the formation of equatorial plasma bubbles (EPBs) there. We find that the simulated GWs, TIDs and EPBs agree with EISCAT, PFISR, GNSS, and SuperDARN measurements. We find that the higher-order GWs are concentrated at 60-90 degrees $60-90{}<^>{\circ}$N at z >= $z\ \ge $ 200 km, in agreement with GOCE and CHAMP data. Thus the polar vortex jet is important for generating TIDs in the northern winter ionosphere via multi-step vertical coupling through GWs.

We present a multi-year climatology of Large Scale Traveling Ionospheric Disturbance (LSTID) period oscillations observed using 14 MHz amateur (ham) radio data. Traveling ionospheric disturbances (TIDs) are quasi periodic electron density perturbations in the F region ionosphere that affect radio communications and can help with understanding energy transport throughout the coupled magnetosphere-ionosphere-neutral atmosphere system. These are seen, in daytime, as variations in contact ranges in 14 MHz amateur radio communication reports recorded by automated monitoring systems such as the Weak Signal Propagation Reporting Network (WSPRNet), the Reverse Beacon Network (RBN), and PSKReporter. A new deterministic and fully automated method was developed for identifying and quantifying these disturbances. This technique, which filters for TID wave periods between 1 and 5 hours and curve fits a sinusoidal function to the first hop skip-distance edge of observed communication ranges, provides both TID amplitudes and periods. In this study, we present full year climatologies of LSTID events over the continental United States (CONUS) using RBN, WSPRNet, and PSK observations from 2016–2021. Results are organized as a function wave period, amplitude, and season. We find that LSTIDs increase in winter and decline during the fall and spring, with slight enhancements in the summer and occasional brief declines in LSTID winter activity. This seasonal pattern shows consistency with previous studies and observations of LSTIDs and medium scale TIDs that suggests this behavior may be associated with neutral wind filtering in the middle atmosphere, sudden stratospheric warming (SSW) events, and multi-step vertical coupling (MSVC) processes. MSVC is a process where gravity waves (GWs) from the lower neutral atmosphere propagate upwards, break, and produce new, higher-order GWs in the thermosphere and TIDs in the ionosphere.

This paper presents a study of the global medium-scale (scales<620 km) gravity wave (GW) activity (in terms of zonal wind variance) and its seasonal, local time, and longitudinal variations by employing the enhanced-resolution (similar to 50 km) whole atmosphere model (WAMT254) and space-based observations for geomagnetically quiet conditions. It is found that the GW hotspots produced by WAMT254 in the troposphere and stratosphere agree well with previously well-studied orographic and nonorographic sources. In the ionosphere-thermosphere (IT) region, GWs spread out forming latitudinal band-like hotspots. During solstices, a primary maximum in GW activity is observed in WAMT254 and GOCE over winter mid-high latitudes, likely associated with higher-order waves with primary sources in polar night jet, fronts, and polar vortex. During all the seasons, the enhancement of GWs around the geomagnetic poles as observed by GOCE (at similar to 250 km) is well captured by simulations. WAMT254 GWs in the IT region also show dependence on local time due to their interaction with migrating tides leading to diurnal and semidiurnal variations. The GWs are more likely to propagate up from the MLT region during westward/weakly eastward phase of thermospheric tides, signifying the dominance of eastward GW momentum flux in the MLT. Additionally, as a novel finding, a wavenumber-4 signature in GW activity is predicted by WAMT254 between 6 and 12 local times in the tropics at similar to 250 km, which propagates eastward with local time. This behavior is likely associated with the modulation of GWs by wave-4 signal of nonmigrating tides in the lower thermospheric zonal winds.

We analyze an episode of strong mountain wave (MW) activity over the western US from 9 to 12 January 2017 using the HIgh Altitude mechanistic General Circulation Model. We find that medium-scale MWs were generated by strong eastward flow over the Sierra Nevada and the Rocky Mountains. During this time, part of the stratospheric polar vortex jet extended from the western US to eastern Canada such that the MWs propagated into the lower mesosphere where they dissipated from westward vertical wind shear. This resulted in secondary gravity waves (GWs) that propagated into the lower thermosphere where tertiary GWs having concentric ring structures were created. With increasing altitude in the thermosphere, certain propagation directions were highlighted as a result of the dissipation induced by the tidal winds. At 260 km, we find eastward propagation during local morning over the northeastern US, equatorward propagation around local noon over the southern US, westward propagation during local afternoon over the northwestern US, and poleward propagation over Canada after local midnight. In addition, the model shows equatorward propagating larger-scale GWs over Canada from remote sources around local noon. The simulated regional GW-mean flow interaction patterns are consistent with multi-step vertical coupling triggered by the MWs. The traveling ionospheric disturbances (TIDs) during the MW event are simulated with the ionospheric model SAMI3. The simulated GWs and TIDs are consistent with the medium-to-large-scale TIDs observed over the continental US in GPS TEC data.

Planetary wave (PW) modulation of gravity wave (GW) dissipation has long been proposed as a source of longitudinal variability in the mesosphere and lower thermosphere. However, direct measurements of GW drag are rare. We identify 2‐day wave variations in GW momentum fluxes measured by the Southern Argentina Agile Meteor Radar (SAAMER) in Rio Grande, Tierra del Fuego, and a meteor radar at the Andes Lidar Observatory (ALO) in Cerro Pachon, Chile. Typical amplitudes range from 1 to 5 and are generally, though not always, out of phase with the horizontal wind consistent with wind‐induced dissipation of upward‐propagating GWs. The 2‐day wave‐modulated GW drag ranges between 20 and 140 m and can amplify, damp, and alter the phase of the 2‐day wave. These multiple relationships between the GW drag and the 2‐day wave suggest that in situ processes may influence GW drag, including secondary GWs excited from the breakdown of primary GW packets.

The Hunga Tonga-Hunga Ha‘apai (HTHH) volcanic eruption on 15th January 2022 was an unprecedented event and a unique opportunity to investigate volcanic-caused gravity waves (GW) and their global propagation. In this study, we have combined all the available meteor radar observations and data analysis to identify the HTHH GW in the observations. Our results are compared to model-based wind perturbations from HIAMCM of secondary waves that are forced by the GW model MESORAC using GOES-17 observations. Furthermore, we leverage the GW polarization relations to identify different wave features in the observations and perturbation runs with HIAMCM. There is a remarkable agreement in the observed phase speeds for the eastward and westward GW propagation between the observations and HIAMCM wind perturbations indicating that the mesospheric HTHH GW are explainable by secondary waves generated by breaking of the primary GWs from the eruption. We also shed some light on the importance of the quasi-2-day wave on the HTHH GW propagation.

Every evening, the sunset removes the primary energy input to the upper atmosphere, causing rapid atmospheric cooling and generating disturbances called solar terminator waves (STWs). Although they theoretically occur every night, STWs remain poorly understood, partially because the rapidly changing atmospheric conditions near sunset make measurements challenging. This study examines neutral wind measurements from the Michelson Interferometer for Global High-resolution Thermospheric Imaging (MIGHTI) on board NASA's Ionospheric Connection Explorer (ICON) observatory to uncover signatures of STWs. We report the north-south wind signatures of STWs and their altitude profile from 200 to 300 km, both of which have never been previously reported. We show that STWs are some of the largest amplitude dynamical features above 200 km near solstices, but are much weaker near equinoxes. By comparing our observations with the outputs of four different models, we find that STWs are likely generated directly or indirectly (from wave propagation) below 97 km. Future work is necessary to better understand how STWs are generated, how they vary on a daily basis, and the extent of their impacts on Earth's upper atmosphere.

We analyze the gravity waves (GWs) from the ground to the thermosphere during 11-14 January 2016 using the nudged HI Altitude Mechanistic general Circulation Model. We find that the entrance, core and exit regions of the polar vortex jet are important for generating primary GWs and amplifying GWs from below. These primary GWs dissipate in the upper stratosphere/lower mesosphere and deposit momentum there; the atmosphere responds by generating secondary GWs. This process is repeated, resulting in medium to large-scale higher-order, thermospheric GWs. We find that the amplitudes of the secondary/higher-order GWs from sources below the polar vortex jet are exponentially magnified. The higher-order, thermospheric GWs have concentric ring, arc-like and planar structures, and spread out latitudinally to 10 - 90 degrees N. Those GWs with the largest amplitudes propagate against the background wind. Some of the higher-order GWs generated over Europe propagate over the Arctic region then southward over the US to similar to 15-20 degrees N daily at similar to 14 - 24 UT (similar to 9 - 16 LT) due to the favorable background wind. These GWs have horizontal wavelengths lambda H similar to 200 - 2,200 km, horizontal phase speeds cH similar to 165 - 260 m/s, and periods tau r similar to 0.3 - 2.4 hr. Such GWs could be misidentified as being generated by auroral activity. The large-scale, higher-order GWs are generated in the lower thermosphere and propagate southwestward daily across the northern mid-thermosphere at similar to 8-16 LT with lambda H similar to 3,000 km and cH similar to 650 m/s. We compare the simulated GWs with those observed by AIRS, VIIRS/DNB, lidar and meteor radars and find reasonable to good agreement. Thus the polar vortex jet is important for facilitating the global generation of medium to large-scale, higher-order thermospheric GWs via multi-step vertical coupling. Gravity waves (GWs) are perturbations in the Earth's atmosphere created by various processes. When a GW breaks, it imparts momentum to the atmosphere, which in turn can become unbalanced and generate secondary GWs. The same process happens at higher altitudes where the secondary GWs break, thereby generating higher-order GWs. We simulate the primary, secondary and higher-order GWs on 11-14 January 2016 using a GW-resolving whole atmosphere model. We find that the entrance, core and exit regions of the jet that encircles the polar vortex generate primary GWs. In addition, the polar vortex jet magnifies the amplitudes of higher-order GWs from sources below the jet, such as mountain waves. The resulting higher-order GWs have horizontal wavelengths of hundreds to thousands of km with concentric ring, arc-like and planar structures in the thermosphere. We compare the simulated GWs with AIRS, VIIRS/DNB, lidar, and meteor radar observations and find reasonable to good agreement. The vertical shear of the horizontal wind in the entrance, core and exit regions of the polar vortex jet generate GWs in the stratosphere Higher-order GWs generated over Europe and Asia propagate over the Arctic then southward over the CONUS at similar to 9 - 16 LT due to favorable winds Large-scale GWs with lambda H similar to 3,000 km and cH similar to 650 m/s propagate southwestward across the northern thermosphere at similar to 8-16 LT

The Hunga Tonga–Hunga Ha′apai volcano erupted on 15 January 2022, launching Lamb waves and gravity waves into the atmosphere. In this study, we present results using 13 globally distributed meteor radars and identify the volcanogenic gravity waves in the mesospheric/lower thermospheric winds. Leveraging the High-Altitude Mechanistic general Circulation Model (HIAMCM), we compare the global propagation of these gravity waves. We observed an eastward-propagating gravity wave packet with an observed phase speed of 240 ± 5.7 m s−1 and a westward-propagating gravity wave with an observed phase speed of 166.5 ± 6.4 m s−1. We identified these waves in HIAMCM and obtained very good agreement of the observed phase speeds of 239.5 ± 4.3 and 162.2 ± 6.1 m s−1 for the eastward the westward waves, respectively. Considering that HIAMCM perturbations in the mesosphere/lower thermosphere were the result of the secondary waves generated by the dissipation of the primary gravity waves from the volcanic eruption, this affirms the importance of higher-order wave generation. Furthermore, based on meteor radar observations of the gravity wave propagation around the globe, we estimate the eruption time to be within 6 min of the nominal value of 15 January 2022 04:15 UTC, and we localized the volcanic eruption to be within 78 km relative to the World Geodetic System 84 coordinates of the volcano, confirming our estimates to be realistic.

Atmospheric predictability from subseasonal to seasonal time scales and climate variability are both influenced critically by gravity waves (GW). The quality of regional and global numerical models relies on thorough understanding of GW dynamics and its interplay with chemistry, precipitation, clouds, and climate across many scales. For the foreseeable future, GWs and many other relevant processes will remain partly unresolved, and models will continue to rely on parameterizations. Recent model intercomparisons and studies show that present-day GW parameterizations do not accurately represent GW processes. These shortcomings introduce uncertainties, among others, in predicting the effects of climate change on important modes of variability. However, the last decade has produced new data and advances in theoretical and numerical developments that promise to improve the situation. This review gives a survey of these developments, discusses the present status of GW parameterizations, and formulates recommendations on how to proceed from there.

Thermospheric wind measurements above 200 km show a prominent migrating wave associated with the evening solar terminator.• The first observations of solar terminator wave altitude profiles reveal > 200 km vertical wavelengths above 200 km.• Comparison with numerical models suggests a lower atmospheric origin and the potentially significant role of gravity waves.

We simulate the gravity waves (GWs) and traveling ionospheric disturbances (TIDs) created by the Hunga Tonga-Hunga Ha'apai (hereafter "Tonga") volcanic eruption on 15 January 2022 at similar to 04:15 UT. We calculate the primary GWs and forces/heatings generated where they dissipate with MESORAC, the secondary GWs with HIAMCM, and the TIDs with SAMI3. We find that medium and large-scale TIDs (MSTIDs and LSTIDs) are induced by the secondary GWs, with horizontal phase speeds c(H) similar or equal to 100-750 m/s, horizontal wavelengths lambda(H) similar or equal to 600-6,000 km, and ground-based periods tau(r) similar or equal to 30 min to 3 hr. The LSTID amplitudes over New Zealand are similar or equal to 2-3 TECU, but decrease sharply similar or equal to 5,000 km from Tonga. The LSTID amplitudes are extremely small over Australia and South Africa because body forces create highly asymmetric GW fields and the GWs propagate perpendicular to the magnetic field there. We analyze the TIDs from SAMI3 and find that a 30 min detrend window eliminates the fastest far-field LSTIDs. We analyze the GPS/TEC via detrending with 2-3 hr windows, and find that the fastest LSTIDs reach the US and South America at similar to 8:30-9:00 UT with c(H) similar or equal to 680 m/s, lambda(H) similar or equal to 3,400 km, and tau(r) similar or equal to 83 min, in good agreement with model results. We find good agreement between modeled and observed TIDs over New Zealand, Australia, Hawaii, Japan and Norway. The observed F-peak height, hmF2, drops by. 110-140 km over the western US with a 2.8 hr periodicity from 8:00 to 13:00 UT. We show that the Lamb waves (LWs) observed by AIRS with lambda(H) = 380 km have amplitudes that are similar or equal to 2.3% that of the primary GWs at z similar or equal to 110 km. We conclude that the observed TIDs can be fully explained by secondary GWs rather than by "leaked" LWs. Plain Language Summary Gravity waves (GWs) are created by various processes, such as volcanic eruptions. A breaking GW imparts momentum and energy to the atmosphere, which creates secondary GWs. Traveling ionospheric disturbances (TIDs) are created by GWs through collisions between neutral and ion molecules. We simulate the GWs and TIDs created by the Tonga eruption on 15 January 2022. We find that medium and large-scale TIDs (MSTIDs and LSTIDs) are induced by the secondary GWs. These TIDs propagate globally, and have speeds of 100-750 m/s and horizontal scales of hundreds to thousands of km. The fastest TIDs reach the United States and South America at similar to 8:30-9:00 UT; these TIDs have large scales and large periods, in agreement with observations. These LSTIDs can only be seen if they are not "detrended out" when processing the ionospheric data. Previous studies eliminated these LSTIDs by restricting their detrend windows, and then incorrectly suggested that Lamb waves were responsible for the TIDs they observed. Using longer detrend windows, we find good agreement between the modeled and observed TIDs. We find that the observed TIDs can be fully explained by secondary GWs, rather than by the leakage of Lamb waves into GWs.

We present high-resolution simulation results of the response of the ionosphere/plasmasphere system to the 15 January 2022 Tonga volcanic eruption. We use the coupled Sami3 is Also a Model of the Ionosphere ionosphere/plasmasphere model and the HIgh Altitude Mechanistic general Circulation Model whole atmosphere model with primary atmospheric gravity wave effects from the Model for gravity wavE SOurces, Ray trAcing and reConstruction model. We find that the Tonga eruption produced a "super" equatorial plasma bubble (EPB) extending similar to 30 degrees in longitude and up to 500 km in altitude with a density depletion of 3 orders of magnitude. We also found a "train" of EPBs developed and extended over the longitude range 150 degrees-200 degrees and that two EPBs reached altitudes over 4,000 km. The primary cause of this behavior is the significant modification of the zonal neutral wind caused by the atmospheric disturbance associated with the eruption, and the subsequent modification of the dynamo electric field.

A new Cloud Imaging and Particle Size (CIPS) gravity wave (GW) variance data set is available that facilitates automated analysis of GWs entering the mesosphere. This work examines several years of CIPS GW variances from 50 to 55 km in the context of the Arctic and Antarctic polar vortices. CIPS observes highest GW activity in the vortex edge region where horizontal wind speeds are largest, consistent with previously published GW climatologies in the stratosphere and mesosphere. CIPS observes the well‐documented planetary wave (PW)‐1 patterns in GW activity in both hemispheres. In the Northern Hemisphere, maximum GW activity occurs over the North Atlantic and western Europe. In the Southern Hemisphere, maximum GW activity stretches from the Andes over the South Atlantic and Indian Oceans, as expected. In the NH, CIPS GW spatial patterns are highly correlated with horizontal wind speed. In the SH, CIPS GW patterns are less positively correlated with the winds due to increased zonal symmetry and orographic forcing. The Andes Mountains and Antarctic Peninsula, South Georgia Island, Kerguelen/Heard Islands, New Zealand, and Tasmania are persistent sources of orographic GWs. Atmospheric Infrared sounder observations of stratospheric GWs are analyzed alongside CIPS to explore vertical GW coherence and to infer GW propagation and sources. NH midlatitude GW activity is reduced during the January 2021 SSW, as expected. This reduction in GWs leads to a simultaneous reduction in traveling ionospheric disturbances (TIDs), providing more evidence that weak polar vortex events with weak GW activity leads to reduced daytime TID activity.

We simulate the primary and secondary atmospheric gravity waves (GWs) excited by the upward movement of air generated by the Hunga Tonga‐Hunga Ha'apai (hereafter “Tonga”) volcanic eruption on 15 January 2022. The Model for gravity wavE SOurce, Ray trAcing and reConstruction (MESORAC) is used to calculate the primary GWs and the local body forces/heatings generated where they dissipate. We add these forces/heatings to the HIgh Altitude Mechanistic general Circulation Model (HIAMCM) to determine the secondary GWs and large‐scale wind changes that result. We find that a wide range of medium to large‐scale secondary GWs with concentric ring structure are created having horizontal wind amplitudes of u ′, v ′ ∼ 100–200 m/s, ground‐based periods of τ r ∼ 20 min to 7 hr, horizontal phase speeds of c H ∼ 100–600 m/s, and horizontal wavelengths of λ H ∼ 400–7,500 km. The fastest secondary GWs with c H ∼ 500–600 m/s are large‐scale GWs with λ H ∼ 3,000–7,500 km and τ r ∼ 1.5–7 hr. They reach the antipode over Africa ∼9 hr after creation. Large‐scale temporally and spatially varying wind changes of ∼80–120 m/s are created where the secondary GWs dissipate. We analyze the Tonga waves measured by the Michelson Interferometer for Global High‐resolution Thermospheric Imaging (MIGHTI) on the National Aeronautics and Space Administration Ionospheric Connection Explorer (ICON), and find that the observed GWs were medium to large‐scale with c H ∼ 100–600 m/s and λ H ∼ 800–7,500 km, in good agreement with the simulated secondary GWs. We also find good agreement between ICON‐MIGHTI and HIAMCM for the timing, amplitudes, locations, and wavelengths of the Tonga waves, provided we increase the GW amplitudes by ∼2 and sample them ∼30 min later than ICON.

&lt;p&gt;Atmospheric Gravity Waves (AGWs) forced in the lower atmosphere are known to have a significant impact on the mesosphere and lower thermosphere (MLT) region. In the ionosphere, they can generate Medium-Scale Traveling Ionospheric Disturbances (MSTIDs). These disturbances roughly occur on time scales of 15&amp;#8722;80 min and are therefore often parametrized rather than directly resolved in ionosphere models. The energy and momentum transport by AGW-TIDs strongly depends on their wave parameters. Measurements of AGW-TIDs in the MLT region and determination of the wave parameters (vertical and horizontal wavelength, wave period and propagation direction) are therefore an essential step to improve ionosphere modelling. However, measurements that provide a good resolution in the vertical dimension (&amp;#8818; 10 km) and time (&amp;#8818; 10 min) as well as a large enough coverage in the horizontal dimension (&amp;#8819; 300 &amp;#215; 300 km) are difficult at MLT altitudes. We show, that combined measurements of the EISCAT VHF incoherent scatter radar and the Nordic Meteor Radar Cluster allow to determine the wave parameters of AGW-TIDs across the whole MLT region. Fourier filter methods are used to separate wave modes by wavelength, period and propagation direction. The extracted wave modes are fitted with wave functions in time-altitude and horizontal cross sections which gives the wave parameters. The coverage regions of the two applied instruments are separated only by approximately 10 km in altitude, which allows to identify a single wave mode in both measurements. We present the developed techniques on the example of a strongly pronounced AGW-TID measured on July 7, 2020. As a first application, two measurement campaigns have been conducted in early September and mid-October 2022 to study possible changes in AGW-TID parameters due to the MLT fall transition occurring around equinox. Another possible application of our method is to infer thermospheric neutral winds from the observed waves. We demonstrate this process under the assumption of the anelastic dissipative gravity wave dispersion relation.&lt;/p&gt;