# Geophysical Research Letters®

## RESEARCH LETTER

10.1029/2024GL109284

**Key Points:**

* The 18 November 2023 Starship flight and explosions generated large-scale multi-oscillation supersonic conic waves in the ionosphere

* The cone angle of the V-shaped ionospheric disturbances corresponds to the Mach angle of shock waves propagating in the lower ionosphere

* The shock waves from the Starship explosion caused a depletion in total electron content (TEC)

**Supporting Information:**

Supporting Information may be found in the online version of this article.

**Correspondence to:**

Y. V. Yasyukevich,
yu.yasyukevich@gnss-lab.org

**Citation:**

Yasyukevich, Y. V., Vesnin, A. M., Astafyeva, E., Maletckii, B. M., Lebedev, V. P., & Padokhin, A. M. (2024). Supersonic waves generated by the 18 November 2023 Starship flight and explosions: Unexpected northward propagation and a man-made non-chemical depletion. *Geophysical Research Letters*, *51*, e2024GL109284. https://doi.org/10.1029/2024GL109284

Received 14 MAR 2024

Accepted 30 JUL 2024

© 2024. The Author(s).
This is an open access article under the
terms of the Creative Commons
Attribution License, which permits use,
distribution and reproduction in any
medium, provided the original work is
properly cited.

<figure><img src="image_1.png" /></figure>

## Supersonic Waves Generated by the 18 November 2023 Starship Flight and Explosions: Unexpected Northward Propagation and a Man-Made Non-chemical Depletion

Y. V. Yasyukevich¹, A. M. Vesnin¹, E. Astafyeva², B. M. Maletckii², V. P. Lebedev¹, and A. M. Padokhin¹,³

¹Institute of Solar-Terrestrial Physics SB RAS, Irkutsk, Russia, ²Université Paris Cité, Institut de Physique du Globe de Paris (IPGP), CNRS UMR, Paris, France, ³Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation, Russian Academy of Sciences, Moscow, Russia

**Abstract** On 18 November 2023, SpaceX launched the Starship, the tallest and the most powerful rocket ever built. The Super Heavy engine separated from the Starship spacecraft and exploded at 90 km of altitude, while the main core Starship continued to rise up to 149 km and exploded after ~8 min of flight. In this work, we used data from ground-based GNSS receivers and we analyzed total electron content (TEC) response to the Starship flight and the two explosions. For the first time, we observed large-distance northward propagation of intensive 2,000 km V-shaped ionospheric disturbances from the rocket trajectory. The observed perturbations, most likely, represent shock waves propagating with the cone angle of ~14° on the North and ~7° on the South against the flight track that corresponds to the Mach angle of the shock waves in the lower atmosphere. The Starship explosion also produced a non-chemical depletion in the ionospheric TEC.

**Plain Language Summary** On 18 November 2023, SpaceX launched the Starship, the tallest and the most powerful rocket ever built. About 2 min and 40 s after the liftoff, the Super Heavy engine separated from the Starship spacecraft and exploded at an altitude of 90 km. The main core Starship continued to rise to 149 km and exploded as well. The rocket launch and explosion produced an unexpected response in the ionosphere—the ionized part of the Earth's atmosphere. The Starship flew at a velocity, exceeding the local sound speed, and generated cone-like atmospheric shock-acoustic waves. Most unexpectedly, the observed disturbances represented long and intensive multi-oscillation wave structures that propagated northward, which is unusual for disturbances driven by a rocket launch. The Starship explosion also generated a large-amplitude total electron content depletion that could have been reinforced by the impact of the spacecraft's fuel exhaust in the lower atmosphere. This study appears to be the first-time detection of a non-chemical ionospheric hole produced by a man-made explosion.

## 1. Introduction

The ionosphere is sensitive to numerous solar and geophysical phenomena, such as solar flares and geomagnetic storms, but also to near-surface events, such as natural hazards, explosions and rocket launches (e.g., Afraimovich et al., 2013; Astafyeva, 2019).

Due to gaseous exhaust stream and their supersonic motion, rocket and missile launches generate acoustic and shock-acoustic waves, and are often seen in the ionosphere as N-like perturbations (Afraimovich et al., 2000, 2002; Calais & Minster, 1996; Choi & Hong, 2019; Lin et al., 2014). The disturbances are usually detected along the rocket's trajectory, and they propagate at speeds 800–1,200 m/s, which is close to the sound speed at the ionosphere altitude (Afraimovich et al., 2002; Chou et al., 2018; Ding et al., 2014; Kiryushkin et al., 2008). In some cases, the propagation speed of such disturbances can exceed the sound speed and reach as high as 1.8–2.6 km/s (Choi & Hong, 2019; Kakinami et al., 2013; Wang et al., 2023). The periods of such waves have been reported to range from tens of seconds to 10 min.

Up to now, ionospheric disturbances driven by rocket launches showed two main types of spatial propagation: V-shape and circular shape. The V-shape has been explained by the rocket speed exceeding the sound speed, when a “bow shock wave” formed by acoustic waves appears along the rocket trajectory (Chou et al., 2018; Ding et al., 2014; Kakinami et al., 2013; Lin et al., 2014). Circular waves are the perpendicular cut and projection of the
<figure><img src="image_2.png" /><figcaption>**Figure 1.** (a) Location of GNSS receivers (dots) and the trajectory of the 18 November 2023 Starship flight (orange line). Red triangle marks the Starbase Orbital Pad, red cross—the position of the Super Heavy booster explosion, red star—an approximate position of the Starship explosion. The cyan part of the trajectory shows Starship debris position recorded by meteo radars. Colored dots mark selected GNSS receivers located northward (green) and southward (blue) from the Starship trajectory. The blue and green curved arrows show IPP for gcea-G10 and chin-G10; (b) 2–10 min TEC variations as recorded by satellite G10 and the GNSS stations northward (green) and southward (blue) from the Starship trajectory. Station names are shown on the right. Station series arranged against the distance from the Starship explosion.</figcaption></figure>

bow-waves (Chou et al., 2018). Similar V-shaped disturbances propagating at near sound speed velocities were observed during the 2013 Chelyabinsk bolide event (Bernardt et al., 2015).

In addition to shock-acoustic waves, rocket and missile launches can affect the local ionosphere chemically and produce ionospheric depletions, or holes (Bernhardt et al., 1982, 2012; Booker, 1961; Bowden et al., 2020; Choi & Kil, 2017; Chou et al., 2018; Furuya & Heki, 2008; Liu et al., 2018; Mendillo et al., 1975; Ozeki & Heki, 2010; Savastano et al., 2019). The holes occur when neutral atoms and molecules are produced due to the rocket fuel burning, and the charge exchange of the exhaust molecules with ambient atomic ions to form molecular ions, and recombination of these molecular ions (Bernhardt, 1987; Bernhardt et al., 1982, 2012). The depletion in the electron density can emerge as fast as ~6 min after the launches (Furuya & Heki, 2008; Ozeki & Heki, 2010), but it can also last up to ~3 hr (Savastano et al., 2019).

This work is the first study of spatial and temporal ionospheric variations produced by the Starship launch on 18 November 2023. For the first time, we observe northward propagation of ionospheric disturbances driven by rocket launch. Also for the first time, we demonstrate that the cone angle of the V-shaped ionospheric disturbances corresponds to the Mach angle of shock waves propagating at 100–150 km of altitude. Finally, also for the first time, we show the occurrence of a launch-related ionospheric depletion of a non-chemical origin.

## 2. Starship Launch and Flight

SpaceX's Starship is currently the largest and the most powerful rocket ever built. When fully fueled, Starship weighs approximately 5,000 tons. Starship is a two-stage super heavy launch vehicle that consists of the Super Heavy booster (or the first stage) and the Starship spacecraft (the second stage).

On 18 November 2023, SpaceX performed the second integrated flight test of Starship. The rocket was launched at 13:02:53 UT from the Starbase Orbital Pad site near Boca Chica in South Texas (26.0°N, -97.2°E; Figure 1, Table S1 in Supporting Information S1). At 13:05:31 UT, while at 70 km of altitude, Starship executed a successful hot-stage separation. After the separation, Super Heavy booster initiated the boostbak burn but exploded at 13:06:11 UT at the altitude of ~90 km. Whereas, the core Starship continued to fly up to 149 km of altitude where it exploded at 13:11:23 UT. The exact location of the Starship explosion is not known, but data from two-line element set (TLE) from https://flightclub.io indicate that the Starship exploded at 24.4308° N, -84.7591°E. We digitized a picture of the debris from Starship ("SpaceX Ship 25") re-entering the atmosphere after the explosion
as seen on the National Weather Service's radar products and we plot them in cyan in Figure 1. One can see that the debris continued to propagate for a long distance along the estimated trajectory after the explosion.

### 3. Data and Methods

To investigate the ionospheric response to the Starship flight and explosions, we used data from ground-based GNSS receivers. The International GNSS Service (IGS Dow et al., 2009) receiver network and other networks were involved (Central Washington University, 1996; Fortes et al., 1998; Gao et al., 1996; Gravelle et al., 2019; Istituto Nazionale di Geofisica e Vulcanologia (INGV), 2016) (Figure 1a).

Ionospheric total electron content $I\varphi$ (in m$^{-2}$, 10$^{16}$ m$^{-2}$ = 1 TECU) was calculated from dual-frequency carrier phase measurements (Afraimovich et al., 2013; Hernández-Pajares, 2022; Hofmann-Wellenhof et al., 2008; Rideout & Coster, 2006):

$$I\varphi = \frac{1}{40.308} \frac{f_1^2 f_2^2}{f_1^2 - f_2^2} (\lambda_1 L_1 - \lambda_2 L_2) \quad (1)$$

where $f_1, f_2$ are the GNSS operating frequencies, $\lambda_1, \lambda_2$ are the phase ranges at $L_1$ and $L_2$ frequencies. We ignored phase ambiguity and phase noise. The altitude of GNSS detection is taken at 300 km. The measurements are associated with ionospheric pierce points (IPP) at 300 km.

TEC data series contain a trend due to GNSS satellite motion. Because the trend represents a significant variation (Maletckii et al., 2020), we applied smoothing splines and running average procedures in the range 2–10 min in order to remove the trend and to highlight the variations related to the Starship effect.

### 4. Results

#### 4.1. Temporal and Spatial Evolution of Ionospheric Response

Figure 1b shows TEC variations recorded by different GNSS stations and satellite G10. The data series are arranged against the distance from the Starship explosion.

The first TEC response can be seen at station CN16 at 13:10:00 UT, which is 8 min after the liftoff, ~4 min after the engine explosion and seconds after the Starship explosion. Figure 1 shows the difference in response with respect to the location of ionospheric points relative to the Starship trajectory. On the south, some stations show a classic N-like response (e.g., Afraimovich et al., 2002) with amplitude of ~1.1 TECU and period of ~10 min. These waves are followed by shorter period TEC oscillations (2–3 min) and smaller amplitudes (~0.2–0.3 TECU) after 13:30:00UT. We also notice visible propagation of these waves from the epicenter. On the north, we observe multiple oscillations with period of ~5–7 min, and amplitudes of 0.6–1.2 TECU.

Figure 2 shows snapshots of the temporal evolution of ionospheric disturbances filtered in the range of 2–10 min. The full picture can be seen in Movie S1 (Supporting Information S1). The disturbance starts to be visible from 13:09UT along the trajectory of the Starship flight (Figure 2a). It first spreads southward and eastward from the trajectory and to the final explosion location (Figures 2b and 2c). From 13:17–13:19UT, we start to observe the cone-like wavefront northward and north-eastward from the trajectory at ~80°–85°W of longitude. Concurrently, we also observe waves coming from the location of the first explosion. These fronts further propagate north-eastward and seem to merge into a single wavefront of ~2,000 km length (Figures 2e–2h, Movie S1). Starting from ~13:35UT, other fronts propagate north-eastward from the trajectory (Figures 2g–2i). Overall, we observe generation and propagation of at least three intensive TEC disturbances, which is in line with temporal variations shown in Figure 1. These half-cone disturbances travel as far as 35°N, that is, ~1,000 km away from the location of the Starship explosion.

On the south from the Starship trajectory, the waveforms are more complex. We observe small-scale TEC increases and decreases, and generation of a cone-like disturbance at 13:35–13:37UT (Figures 2g and 2h). At 13:44UT, a small TEC depletion can be seen along 15°N (Figure 2i). Overall, we record a clear plane structure only close to the flight trajectory.
<figure><img src="image_3.png" /><figcaption>**Figure 2.** Snapshots of TEC disturbances recorded during the 18 November 2023 Starship flight. The triangle marks the Starbase Orbital Pad, the cross sign indicates the location of the Super Heavy booster explosion, the star—location of the Starship explosion. The corresponding moments of time are shown at the bottom of each panel.</figcaption></figure>

Concerning the cone-like disturbance, based on the TEC snapshots at 13:21:00UT and 13:35:00UT (Movie S1, Figures 2g and 3a), we estimate the angle between the flight trajectory and V-shape wave to be ~14° for the Northern part and ~7° for the Southern part. Therefore, the Mach angle was ~11°—that agrees with the estimated Mach cone at the altitude of 100–150 km (Figures 3b and 3c). Further, from the geographic location of the wavefronts at 13:21:00UT (marked “T1” in Figure 3a), and at 13:35:00UT, we estimated the TID velocity as ~750 m/s and wave vector azimuth as ~19°.
<figure><img src="image_4.png" /><figcaption>**Figure 3.** (a)—Cone waves observed in the 2–10 min TEC variations and the trajectory of the 18 November 2023 Starship flight. T1 marks the wavefront at 13:21:00 UT. The arrow marks distances for different (arbitrary) IPP (D1, D2, D3, D4, D5); (b)—altitudinal profiles for the sound speed (blue) and the Starship velocity (orange); (c)—Mach number (M, green) and Mach angle (μ = arcsin (1/M), red) related to the Starship propagation speed; (d)—Distance-time diagrams plotted using 2–10 min TEC variations for the North direction (satellite G10). Vertical dashed line indicates the time of the Starship explosion. Dotted oblique line corresponds to horizontal velocity Vh of the cone wave (not meridional projection) corrected by its azimuth.</figcaption></figure>

## 4.2. Distance-Time Diagrams

Usually, the apparent velocities of ionospheric disturbances are estimated from distance-time diagrams, or keograms (Calais et al., 2003). The diagram is a two-dimension map of TEC variations with time after an event (i.e., the explosion) versus the distance of IPP from the source. The disturbance in distance-time diagrams would reveal a line with a slope corresponding to the disturbance velocity.
<figure><img src="image_5.png" /><figcaption>**Figure 4.** TEC depletion observed around the 18 November 2023 Starship explosion location. (a, b) Positions of GNSS stations and their IPP trajectories for satellites G32 (a) and G15 (b). The dotted ovals mark an approximate area of the observed depletion, the red stars mark the explosion location; (c, d) variations of slant unfiltered TEC and the approximate depletion duration (gray area). The reference dashed lines are calculated by using second degree polynomial fitting by taking TEC values before the wave arrival and at the end of the data series. Stars and squares mark local TEC maximum and minimum, correspondingly.</figcaption></figure>

To calculate the horizontal speed of the cone-like wave (that has a plane wavefront projection), we calculated the distance from the cone (Figure 3a, arrows) rather than the Starship explosion location. To do that, we used a cone with wavefront azimuths of 19° (the North part) and 7° (the South) with the center at the Starship explosion. Choosing the cone center shifts the starting distance, however, the planar wave propagation will lead to the line in the diagram. To estimate velocity, we calculated meridional speed and then corrected it by wave cone azimuths.

Figures S2 in Supporting Information S1 and Figure 3d show a distance-time diagram for 2–10 min TEC variations data. The dotted lines correspond to slopes of wave phase front propagation. The labels correspond to horizontal velocities Vh. For the north direction (Figure 3d) we observe the disturbance starting at 500 km on the Starship explosion longitude. That corresponds to Figures 2 and 3a where we see that the cone head shifted to the east resulting in a northward shift at the Starship explosion longitude.

In the northern direction, we observed wave fronts propagating with Vh = ~750 m/s till ~1,000 km to the North from the initial front and for 4-8th cycle oscillations reaching ~2,000 km (to the North) from the initial front. The velocity corresponds to shock acoustic waves at ionospheric altitudes (Afraimovich et al., 2002). Out of the total 8 cycle oscillations, the last two seem to interfere with slower waves of ~280 m/s with three oscillations.

In the south direction, we observe fast propagation (Vh > 2,000 m/s, Figure S2 in Supporting Information S1). We consider it to be connected with debris or fuel inertial flight even after the explosion.

To analyze data for the eastern (Figure S2c in Supporting Information S1) direction we use the usual distant-time following (Calais et al., 2003): we assume that the Starship explosion is the source of the disturbances in that direction. First, we recorded >2,000 m/s supersonic wave. Most probably, it is connected to the supersonic propagation of the flight-driven disturbance. We note that 15 min after the Starship explosion we observe waves with a velocity of ~500 m/s.
### 4.3. Ionospheric Depletion

Figures 4c and 4d show unfiltered slant TEC variations as recorded by different GNSS stations (marked by dots in Figures 4a and 4b) and by satellites G32 and G15, respectively. One can see the occurrence of a significant TEC decrease, about −10–15 TECU, after a small positive peak of 1–4 TECU. In data of satellite G15, the initial large-amplitude depletion seems to recover in ~6–8 min, and in some data series, the TEC remains depleted for 30–40 min (Figure 4d). Similar pattern is also seen in data of satellite G32 (Figure 4c). Such waveforms are similar to the ionospheric TEC response to large earthquakes (e.g., Astafyeva et al., 2011, 2013; Kakinami et al., 2013) and the 2022 eruption of the Hunga-Tonga volcano (e.g., Aa et al., 2022; Astafyeva et al., 2022; He et al., 2023). In the case of large earthquakes, the occurrence of ionospheric depletions is explained by large nonlinear shock-acoustic waves propagating from the ground to the atmosphere/ionosphere, and causing significant downward ionospheric transport that leads to enhanced charge exchange of O+ and its conversion into molecular ions, and correspondingly to higher recombination (Zettergren et al., 2017). We note that the 2023 Starship event depletion was larger in amplitude but shorter in duration as compared to the 2011 Tohoku earthquake, which could be explained by the source position (i.e., the explosion) in the lower atmosphere that had much stronger impact than an earthquake.

Observation of depletions after rocket and missile launches is not new. Such ionospheric holes occur because of chemical reactions between the rocket fuel exhaust and the ambient ionosphere (Bernhardt, 1982; Bernhardt et al., 1982, 2012; Chou et al., 2018; Furuya & Heki, 2008; Ozeki & Heki, 2010; Savastano et al., 2019). However, the depletions of chemical origin are not preceded by a positive peak, as in the case of the November 2023 Starship event. Moreover, the observed TEC depletion is smaller in both amplitude and duration with respect to previous rocket and missile launches, which could be explained by the fact that the Starship exploded at the height of 149 km, and it did not reach the altitude where the charge exchange reactions could occur converting atomic ions into neutrals and causing a hole (Bernhardt, 1987; Bernhardt et al., 1982, 2012).

To investigate the origin of the observed depletion, we analyzed the ionospheric TEC response to two more recent launches of Starship that took place on 14 March 2024 and 06 June 2024. The latter two launches went as planned and did not explode, or at least not in the considered region. The parameters of these launches are similar to the November 2023 one (Tables S2 and S3 in Supporting Information S1). In both the March 2024 and June 2024 cases, we observe large N-waves and smaller-amplitude oscillations (Figures S4 and S5 in Supporting Information S1). Predominant N-waves were located close to the flight tracks during all three launches (Figure S6 in Supporting Information S1), but a depletion only occurred during the November 2023 event (see Figure S3–S6 in Supporting Information S1).

Therefore, based on these results, we conclude that the observed depletion was due to the shock wave generated by the Starship explosion in the lower atmosphere. In addition, the local impact of the Starship fuel reaction with the local atmosphere at the altitude of the explosion might have reinforced the depletion and extended its duration.

### 5. Discussion and Conclusions

Above we demonstrated that the launch, the flight, and the two explosions of the Starship on 18 November 2023 generated intensive disturbances and a depletion in the ionospheric TEC. The disturbances were first observed along the Starship trajectory starting from 13:10UT which is ~8 min after the launch time, ~4 min after the first explosion at the altitude of 90 km, and ~5 s after the second explosion at the altitude of 149 km. The temporal and spatial closeness of the explosions make it difficult to distinguish the exact origin of the observed disturbances. Although, at some moments of time, we seem to observe disturbances distinctly traveling from the two explosions (Figure 2).

On the temporal scale, it is known that acoustic waves take about 7–8 min to reach the ionospheric altitudes from the ground. Figure 3b demonstrates that from the altitude of 90 km (the altitude of the first explosion), an acoustic wave would have an averaged speed of 637 m/s, that is, it would take 330 s (5 min 30 s) to reach 300 km of altitude. From the altitude of 149 km, with the averaged speed of 725 m/s (Figure 3b), acoustic waves would take 208 s (i.e., 3 min 28 s) to reach 300 km of altitude. This means that, considering that we detect them at the same altitude (300 km), we can detect disturbances corresponding to the launch at ~13:10–13:11UT, those due to the first explosion that occurred at 13:06:11UT—at 13:11:41 UT. Finally, acoustic waves from the second explosion that occurred at 13:09:55UT should reach the detection altitude at 13:13:23UT.
It should be noted that Starship flew at a speed much higher than the local sound speed (Table S1 in Supporting Information S1, Figure 3b). For instance, at the altitude of the first explosion, the Booster flew at 1.06 km/s, which is ~3 times higher than the local sound speed. At the altitude of 149 km, just before the explosion, the Starship flew at the velocity higher than 5–6 km/s (Table S1 in Supporting Information S1), which is ~4.5–5 times larger than the sound speed. Therefore, both objects could have generated the bow waves traveling at supersonic speed. This means that they should reach the ionosphere faster, and this could explain the nearly simultaneous occurrence of the disturbances around the areas of the first and the second explosions. Further, such high-speed propagation of the Starship in the eastward direction and the bow wave generated by it could explain such a fast occurrence of the disturbance eastward from the explosion location.

The observed disturbances were V-shaped, with the cone angle of ~11° (14° to the North and ~7° to the South against the flight track), which corresponds to the Mach number at the altitude of 100–150 km.

Finally, multiple characteristics of the disturbances are observed for the first time and will require further investigations:

1. The disturbances showed clear north-south asymmetry in waveforms and the apparent velocities of propagation. Contrary to previous observations that mostly showed equatorward propagation of disturbances from the rocket trajectory, we observe clear long-distance propagation of the V-shaped disturbance to the north from the rocket trajectory. The north-south asymmetry in ionospheric disturbance propagation is usually attributed to the impact of the magnetic field that prohibits the propagation of a disturbance in the poleward direction (Afraimovich et al., 2001; Astafyeva, 2019; Bagiya et al., 2019; Heki & Ping, 2005; Lin et al., 2014; Rolland et al., 2013). Therefore, in the northern hemisphere, we usually observe long-distance propagation of ionospheric disturbances to the south, while when traveling northward, a disturbance driven by a point source fades out at ~100 km horizontal distance from the source. However, the situation is different for disturbances caused by a traveling source, which might be the case in the Starship event.

2. The signal on the north side showed multi-oscillation (wave trains) disturbance of relatively large amplitude. Ding et al. (2014) also observed wave trains but with fewer oscillations and ~10 times less amplitudes (0.1–0.02 TECU). The observed waveforms could be caused by the magnetosphere–ionosphere connection due to the passage of the solar terminator (Afraimovich et al., 2009). However, the dynamics of the wavefront, the location of the disturbance occurrence show that the observed disturbance was caused by the Starship flight. Lin et al. (2014) suggested such “delayed” waves could be caused by atmospheric disturbances propagating from lower altitudes at an earlier rocket stage/time. For the Starship event, it would be true if the waves had a circular (rather than V-shaped) form, which is not the case.

3. The occurrence of a large-amplitude TEC depletion was preceded by a small positive peak. Based on the observed waveforms, we conclude that the large-amplitude depletion was principally caused by the shock waves due to the Starship explosion in the lower atmosphere, and could have been reinforced by the impact of the spacecraft's fuel exhaust. This seems to be the first-time detection of a non-chemical ionospheric hole produced by a man-made explosion.

## Data Availability Statement

All GNSS-TEC data are available from the SIMuRG web-service (https://simurg.iszf.irk.ru/gen_file?data=obs&date=2023-11-18) (Yasyukevich et al., 2020). The software to process the data is available at https://github.com/gnss-lab/studies. We used orbit information from https://flightclub.io/result/2d?llId=04b91bb8-38a7-4868-b025-4bbe05d1fbfe. The debris from SpaceX Ship 25 re-entering the atmosphere after the explosion as seen on the National Weather Service's radar's correlation coefficient—twitted by Jonathan McDowell https://web.archive.org/web/20231120035113/https://twitter.com/planet4589/status/1725917544114974995.

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## Acknowledgments

We acknowledge the SIMuRG team for making the data processing available. The GNSS data are from: the International GNSS service (IGS), Pacific Northwest Geodetic Array (PANGA), INGV—Rete Integrata Nazionale GPS, Instituto Brasileiro de Geografia e Estatística, The Western Canada Deformation Arra, Système d'Observation du Niveau des Eaux Littorales (SONEL), Scripps Orbit and Permanent Array Center, UCSD. GNSS data treatment and software development were financially supported by Russian Science Foundation (project No. 23-17-00157, https://rscf.ru/project/23-17-00157/). EA and BM (geophysical analysis) acknowledge the support of the French National Research Agency (ANR), project IONO-DIET (Grant ANR-22-CE49-0011), and the French Space Agency (CNES), project “RealDetect.” The authors thank Prof. Kosuke Heki and another anonymous reviewer for useful suggestions.
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