Universal Time Variations in the Magnetosphere and the Effect of CME Arrival Time: Analysis of the February 2022 Event that Led to the Loss of Starlink Satellites

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The Polar Cap Indices (PCI) are compiled using data from one magnetometer station in each hemisphere, each close to the geomagnetic pole (Stauning, 2021a(Stauning, , 2021bTroshichev, 2022). The northern hemisphere index, PCN, is from observations made at the Thule (Qaanaaq) in Greenland (IAGA code THL: geographic coordinates 77.47°N, −69.23°E) and the southern hemisphere index, PCS, is from observations made at Vostok (IAGA code VOS: geographic coordinates −79.45°N, 106.87°E). (IAGA is the International Association of Geomagnetism and Aeronomy, one of the eight associations of the International Union of Geodesy and Geophysics). Over the years studied in this paper (1998-2018) there has been a relatively rapid motion of the Northern geomagnetic (eccentric dipole) pole toward the rotational axis and much slower motion of the Southern pole (Koochak & Fraser-Smith, 2017;Lockwood et al., 2021). This has resulted in different motions of the stations in geomagnetic coordinates. This paper employs the Altitude-Adjusted Corrected Geomagnetic Coordinate system AACGMv2 (Shepherd, 2014) and the magnetic coordinates of the two stations in this frame are given in Table 1 for the start, middle and end years of the period studied. This shows 1.50° equatorward motion of THL in the geomagnetic

Section: Discussionmentioning

confidence: 99%

Northern and Southern Hemisphere Polar Cap Indices: To What Extent Do They Agree and to What Extent Should They Agree?

Lockwood

2023

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“…The launch of a series of Starlink S‐36 internet satellites from Cape Canaveral on 3 February 2022, was in accordance with the company's pace of averaging around one launch per week. Contrary to other Starlink launches, the S‐36 launch on 3 February 2022, coincided with the development of a two‐phase geomagnetic storm (Dang et al., 2022; Fang et al., 2022; Hapgood et al., 2022; Kataoka et al., 2022; Lockwood et al., 2023; Tsurutani et al., 2022; Zhang et al., 2022). Storm peaks occurred on February 3, 11 UT (Dst = −66 nT) and February 4, 21 UT (Dst = −61 nT).…”

Section: Introductionmentioning

confidence: 95%

“…Lockwood et al. (2023) suggested that the S‐36 mission failure is attributed to the Coronal Mass Ejection, (CME), and its arrival to Earth at a certain time that gave rise to different deposition of power between the North and South hemispheres due to the offset of the magnetic pole with respect to the geographic pole being considerably higher in the southern hemisphere than in the northern hemisphere.…”

Section: Introductionmentioning

confidence: 99%

“…Tsurutani et al ( 2022) introduced a scenario with the prompt penetration electric fields which led to enhanced dayside low latitude satellite drag that was sufficient to cause Starlink deorbit several days later. Lockwood et al (2023) suggested that the S-36 mission failure is attributed to the Coronal Mass Ejection, (CME), and its arrival to Earth at a certain time that gave rise to different deposition of power between the North and South hemispheres due to the offset of the magnetic pole with respect to the geographic pole being considerably higher in the southern hemisphere than in the northern hemisphere.The maneuver from 210 to 550 km resulted in a transition through the ionosphere peak electron density, NmF2, at the peak altitude hmF2 varying from 200 to 450 km where conditions of signal propagation driving the maneuver changed dramatically. Hence, investigation of the ionosphere during the S-36 mission deserves special attention (Tsurutani et al, 2022).…”

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confidence: 99%

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Ionosphere Heterogeneities at Dawn−Dusk Terminator Related to the Starlink Satellites Launch Disaster on 3−8 February 2022

Gulyaeva,

Lukianova,

Haralambous

2023

We present an analysis of the evolution of the ionospheric Total Electron Content (TEC) and its variability index Vσ during the Starlink launch disaster on 3–8 February 2022 two‐phase geomagnetic storm. JPL GIM‐TEC global maps with increased spatial (1° in latitude and longitude) and temporal (15 min cadence) resolution as well as SWARM satellite data have been used in the analysis. Comparison of data for five time periods including Starlink launches with geomagnetic Dst index demonstrates thermospheric mass densities increasing by about 50% during the development of the storm on 3–5 February. A spectrum periodogram analysis is applied on TEC at sunrise and sunset solar terminator (STh) at an altitude h = 300 km. Periodicities in the solar terminator TEC generated waves are estimated as 24 hr, 12 hr, 1 hr, 30 min, 20 min, and 15 min. A significant morning−evening asymmetry resulted in the density anomalies concentrated in a certain—evening—sector of terminator when plasma is shifted to the dusk side forming a global asymmetry.

“…Using Equation , the value of F PC throughout the growth phase is also computed and by assuming a circular polar cap this yields the polar cap diameter, d PC (using the equation by Lockwood et al. (2023), based on the work of Milan et al. (2021)).…”

Section: The Effect Of Pole Motions On Substorm Growth Phasesmentioning

confidence: 99%

Universal Time Effects on Substorm Growth Phases and Onsets

Lockwood

2023

Universal Time (UT) variations in many magnetospheric state indicators and indices have recently been reviewed by Lockwood and Milan (2023, https://doi.org/10.3389/fspas.2023.1139295). Key effects are introduced into magnetospheric dynamics by the eccentric nature of Earth's magnetic field, features that cannot be reproduced by a geocentric field model. This paper studies the UT variation in the occurrence of substorm onsets and uses a simple Monte‐Carlo model to show how it can arise for an eccentric field model from the effect of the diurnal motions of Earth's poles on the part of the geomagnetic tail where substorms are initiated. These motions are in any reference frame that has an X axis that points from the center of the Earth to the center of the Sun and are caused by Earth's rotation. The premise behind the model is shown to be valid using a super‐posed epoch study of the conditions leading up to onset. These studies also show the surprising degree of preconditioning ahead of the growth phase that is required, on average, for onset to occur. A key factor is the extent to which pole motions caused by Earth's rotation influence the near‐Earth tail at the relevant X coordinate. Numerical simulations by a global MHD model of the magnetosphere reveal the effect required to generate the observed UT variations and with right order of amplitude, albeit too small by a factor of about one third. Reasons why this discrepancy may have arisen for the simulations used are discussed.