[Paper Review] Ionospheric effects during first 2 hours after the Chelyabinsk meteorite impact

O. I. Berngardt, V. I. Kurkin+3 more|arXiv (Cornell University)|Aug 18, 2013

Astro and Planetary Science13 references4 citations

TL;DR

This study analyzes ionospheric disturbances caused by the Chelyabinsk meteorite impact using EKB radar and PARUS ionosonde data from the Arti Observatory, 200 km north of the explosion site. Despite high-amplitude, dynamic disturbances, no significant change in mean ionospheric parameters (15-min resolution) was observed directly above the impact site within the first two hours; instead, intense effects were detected at distances exceeding 100–200 km, extending up to 1500 km, including short-lived E-layer irregularities and F-layer disturbances propagating radially from the impact center at 250–800 m/s with electron density increases of at least 15%.

ABSTRACT

This paper presents the analysis of ionospheric effects in the region close to the Chelyabinsk meteorite explosion at 03:20UT 2013 February 15 from the Institute of Solar-Terrestrial Physics of Siberian Branch of Russian Academy of Sciences (ISTP SB RAS) EKB radar data, and from the Institute of Geophysics of Ural Branch of Russian Academy of Sciences (IG UB RAS) PARUS ionosonde data. Both instruments are located within the IG UB RAS Arti Observatory approximately 200 km northward from the estimated explosion site. According to the data obtained, the ionospheric disturbance caused by the meteorite flyby, explosion, and impact had high dynamics and amplitude. However, it obviously did not lead to a variation in the ionosphere mean parameters in the region above the disturbance center during the first 2 hours. Essential effects, however, were observed at more than 100-200 km from the explosion site and farther up to 1500 km.

Motivation & Objective

• To investigate ionospheric effects from the Chelyabinsk meteorite impact during the first two hours post-explosion using high-resolution radar and ionosonde data.
• To determine whether the impact caused measurable changes in mean ionospheric parameters (e.g., foF2) at the location directly above the explosion site.
• To identify and characterize transient ionospheric irregularities and wave-like disturbances in the E- and F-layers induced by the meteorite's atmospheric entry and explosion.
• To estimate the spatial extent, temporal evolution, and physical parameters (e.g., electron density, velocity, size) of ionospheric disturbances associated with the event.
• To assess the role of atmospheric gravity waves and ionospheric disturbances in the context of meteor impacts, using the Chelyabinsk event as a case study.

Proposed method

• Utilized EKB radar data from the ISTP SB RAS Arti Observatory, operating in oblique backscatter sounding (OBSS) and backscatter on small-scale irregularities modes, with 60-km range resolution and 4-s integration per beam.
• Analyzed 15-minute resolution foF2 data from the PARUS ionosonde at Arti Observatory to compare background ionospheric conditions on 2013 February 15 with magnetically quiet referential days (Feb 9–12, 18).
• Performed comparative analysis of scattered signal power dynamics at 10 MHz and 16 MHz between the impact day and referential days to detect anomalous radio noise increases.
• Identified and tracked meso-scale ionospheric irregularities in the E-layer (02:47–04:00 UT) and F-layer disturbances (03:20–04:00 UT) using Doppler velocity, spectral width, and spatial extent analysis.
• Estimated the formation height (115 km), plasma frequency (3 MHz), and lifetime (20–40 s) of short-lived E-layer irregularities using signal characteristics and propagation modeling.
• Calculated equivalent ionospheric velocities (250, 400, and 800 m/s) and disturbance amplitudes (≥15% electron density increase) for F-layer disturbances using wave propagation analysis and time delays.

Experimental results

Research questions

• RQ1 Did the Chelyabinsk meteorite impact cause measurable changes in mean ionospheric parameters (e.g., foF2) directly above the explosion site within the first two hours?
• RQ2 What are the spatial and temporal characteristics of ionospheric disturbances in the E- and F-layers following the meteorite explosion?
• RQ3 How do the observed ionospheric irregularities (e.g., E-layer disturbances) relate to the timing and location of the meteorite explosion?
• RQ4 What is the estimated formation height, electron density, and lifetime of the short-lived E-layer irregularity observed 33 minutes before and after the impact?
• RQ5 What are the propagation velocities and horizontal scales of the F-layer disturbances, and how do they relate to the impact site?

Key findings

• No significant variation in the 15-minute mean ionospheric parameters (e.g., foF2) was observed directly above the explosion site during the first two hours, indicating that the ionosphere remained largely quiescent at the radar location.
• A short-lived E-layer irregularity formed at 03:20:32 UT ± 4 s, with a lifetime of 20–40 seconds, a formation height of 115 km, and a plasma frequency of approximately 3 MHz, consistent with a localized electron density burst.
• An unusual meso-scale E-layer irregularity appeared at 02:47 UT, 33 minutes before the explosion, and persisted until 04:00 UT, with a drift velocity of 50 m/s westward, and was absent on referential quiet days.
• A high-velocity disturbance (200 m/s) was detected 400 km southwest of the radar at E-layer height (115 km), propagating away from the radar, with a spectral width up to 33 Hz (equivalent to 500 m/s), indicating strong turbulence.
• F-layer disturbances originated at 03:20 UT, with radial propagation from a center 80–100 km south of the radar, and were observed for up to 80–100 minutes, with equivalent ionospheric velocities of 250, 400, and 800 m/s.
• The amplitude of the F-layer disturbance was at least 15% increase in electron density, with horizontal scales of about 200 km, and the disturbance center was located close to the NASA-estimated impact site.