Determining the Origin of Tidal Oscillations in the Ionospheric Transition Region With EISCAT Radar and Global Simulation Data

Günzkofer, Florian; Pokhotelov, Dimitry; Stober, Gunter; Liu, Huixin; Liu, Hanli; Mitchell, N. J.; Tjulin, Anders; Borries, Claudia

doi:10.1029/2022ja030861

Cited by 8 publications

(9 citation statements)

References 53 publications

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“…One major assumption for the present study was the application of TIE‐GCM neutral winds and ion‐neutral collision frequencies for both measurement and model calculations. It is possible to calculate neutral winds from EISCAT CP2 measurements (Brekke et al., 1973; Günzkofer et al., 2022; Nozawa et al., 2010) but this, in turn, requires knowledge of the ion‐neutral collision frequency. The ion‐neutral collision frequency can be measured from dual‐frequency EISCAT experiments (Grassmann, 1993; Günzkofer, Liu, et al., 2023; Günzkofer, Stober, et al., 2023; Nicolls et al., 2014) which is not possible in combination with beam‐swing measurements.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE‐GCM With EISCAT Measurements

Günzkofer,

Liu,

Stober

et al. 2024

Earth and Space Science

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Joule heating is one of the main energy inputs into the thermosphere‐ionosphere system. Precise modeling of this process is essential for any space weather application. Existing thermosphere‐ionosphere models tend to underestimate the actual Joule heating rate quite significantly. The Thermosphere‐Ionosphere‐Electrodynamics General‐Circulation‐Model applies an empirical scaling factor of 1.5 for compensation. We calculate vertical profiles of Joule heating rates from approximately 2,220 hr of measurements with the EISCAT incoherent scatter radar and the corresponding model runs. We investigate model runs with the plasma convection driven by both the Heelis and the Weimer model. The required scaling of the Joule heating profiles is determined with respect to the Kp index, the Kan‐Lee merging electric field EKL, and the magnetic local time. Though the default scaling factor of 1.5 appears to be adequate on average, we find that the required scaling varies strongly with all three parameters ranging from 0.46 to ∼20 at geomagnetically disturbed and quiet times, respectively. Furthermore, the required scaling is significantly different in runs driven by the Heelis and Weimer model. Adjusting the scaling factor with respect to the Kp index, EKL, the magnetic local time, and the choice of convection model would reduce the difference between Joule heating rates calculated from measurement and model plasma parameters.

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Section: Discussionmentioning

confidence: 99%

Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE‐GCM With EISCAT Measurements

Günzkofer,

Liu,

Stober

et al. 2024

Earth and Space Science

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“…In the following, we apply this method to an AGW-TID event that occurred during the MLT fall transition. The fall transition is connected to the autumn equinox and has been shown to have a major impact on atmospheric tides in the MLT region (Stober et al, 2021d;Pedatella et al, 2021;Günzkofer et al, 2022). Other studies suggest that there is also an impact on the gravity wave forcing from below (Placke et al, 2015) which, in consequence, will alter the observed wave parameters in the ionosphere.…”

Section: Agw-tid Parameters During the Fall Transitionmentioning

confidence: 99%

“…Strong changes in AGW-TID activity in the MLT are caused by the seasonal variation of mesospheric mean winds (Stober et al, 2021d), especially during the spring and fall equinox transitions. The latter in particular has been shown to impact tidal waves in the mesosphere (Stober et al, 2020;Pedatella et al, 2021) and possibly well up in the thermosphere (Günzkofer et al, 2022). Investigating the impact of the MLT fall transition, the change of the MLT wind system around the autumn equinox (Stober et al, 2021d), on AGW-TIDs is one of the central topics of this manuscript.…”

Section: Introductionmentioning

confidence: 98%

Inferring neutral winds in the ionospheric transition region from AGW-TID observations with the EISCAT VHF radar and the Nordic Meteor Radar Cluster

Günzkofer

Pokhotelov

Stober

et al. 2023

Preprint

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Abstract. Atmospheric Gravity Waves and Traveling Ionospheric Disturbances can be observed in the neutral atmosphere and the ionosphere at a wide range of spatial and temporal scales. Especially at medium scales, these oscillations are often not resolved in general circulation models and are parameterized. We show that ionospheric disturbances forced by upward propagating atmospheric gravity waves can be simultaneously observed with the EISCAT Very High Frequency incoherent scatter radar and the Nordic Meteor Radar Cluster. From combined multi-static measurements, both vertical and horizontal wave parameters can be determined by applying a specially developed Fourier filter analysis method. This method is demonstrated using the example of a strongly pronounced wave mode that occurred during the EISCAT experiment on 7 July 2020. Leveraging the developed technique, we show that the wave characteristics of Traveling Ionospheric Disturbances are notably impacted by the fall transition of the mesosphere/lower thermosphere. We also demonstrate the application of using the determined wave parameters to infer the thermospheric neutral wind velocities. Applying the dissipative anelastic gravity wave dispersion relation, we obtain vertical wind profiles in the lower thermosphere.

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“…Whereas ground-based remote sensing facilities have been providing continuous measurements of key LTI parameters as a function of altitude and local time, and are currently a main source of information on ion-neutral interactions across the LTI (see, e.g., Wahlund et al (1992); Rishbeth and Van Eyken (1993); and, as examples of recent studies, e.g. the work by Tesema et al (2022); Günzkofer et al (2022)), there are limitations of remote sensing methods in addressing the science questions outlined herein. These limitations are related to the temporal and spatial resolution that ground-based instruments can provide as well as to the need for co-temporal, co-spatial measurements of all parameters involved.…”

Section: On the Need For In Situ Lower Thermosphere-ionosphere Measur...mentioning

confidence: 99%

Plasma-neutral interactions in the lower thermosphere-ionosphere: The need for in situ measurements to address focused questions

Sarris

Palmroth

Aikio

et al. 2023

Front. Astron. Space Sci.

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The lower thermosphere-ionosphere (LTI) is a key transition region between Earth’s atmosphere and space. Interactions between ions and neutrals maximize within the LTI and in particular at altitudes from 100 to 200 km, which is the least visited region of the near-Earth environment. The lack of in situ co-temporal and co-spatial measurements of all relevant parameters and their elusiveness to most remote-sensing methods means that the complex interactions between its neutral and charged constituents remain poorly characterized to this date. This lack of measurements, together with the ambiguity in the quantification of key processes in the 100–200 km altitude range affect current modeling efforts to expand atmospheric models upward to include the LTI and limit current space weather prediction capabilities. We present focused questions in the LTI that are related to the complex interactions between its neutral and charged constituents. These questions concern core physical processes that govern the energetics, dynamics, and chemistry of the LTI and need to be addressed as fundamental and long-standing questions in this critically unexplored boundary region. We also outline the range of in situ measurements that are needed to unambiguously quantify key LTI processes within this region, and present elements of an in situ concept based on past proposed mission concepts.

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Determining the Origin of Tidal Oscillations in the Ionospheric Transition Region With EISCAT Radar and Global Simulation Data

Cited by 8 publications

References 53 publications

Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE‐GCM With EISCAT Measurements

Evaluation of the Empirical Scaling Factor of Joule Heating Rates in TIE‐GCM With EISCAT Measurements

Inferring neutral winds in the ionospheric transition region from AGW-TID observations with the EISCAT VHF radar and the Nordic Meteor Radar Cluster

Plasma-neutral interactions in the lower thermosphere-ionosphere: The need for in situ measurements to address focused questions

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