Abstract Details


Name: Ajay Kumar
Affiliation: University of Mumbai
Conference ID: TVS202510311
Title: Severe Geomagnetic Storm Driven by a Slow ICME: Revisiting the August 2018 Event
Authors and Co-Authors: Anil Raghav , Ajay Kumar , Omkar Dhamane, Kalpesh Ghag, Kishor Kumbhar , Ankush Bhaskar , S. Tulasiram, Zubair Shaikh , Mohit Shah, Mariyam Karari, Shubham Kadam
Abstract Type: Contributory Presentation
Abstract: On 25 August 2018, Earth encountered a slow moving interplanetary coronal mass ejection (ICME) linked to a CME that erupted on 20 August. Despite its low speed near 440 km/s, low dynamic pressure below 8 nPa, and magnetic field strength under 20 nT, it triggered a severe geomagnetic storm ( SY M −H below −200 nT) with significant global space weather impacts. No sudden storm commencement (SSC) was observed; instead, the storm was driven by a prolonged southward interplanetary magnetic field lasting about 13 hours. Detailed analysis reveals that an interacting high-speed stream (HSS) compressed the trailing edge of the ICME, enhancing proton density and magnetic field strength within the flux rope. This compression likely suppressed the expected expansion and transformed the ICME into a coherent, planar magnetic structure (PMS), with sustained southward fields. Such PMS-like configurations are known to be highly geoeffective. the compressed flux rope coupled efficiently with the dayside magnetosphere, causing significant magnetic erosion and reducing the magnetopause standoff distance below 7 RE . Sector-wise analysis of the SuperMAG ring current indices revealed strong local time asymmetries during the storm’s evolution, further supporting the presence of intense inner magnetospheric disturbances. These results demonstrate the role of internal ICME structure in storm development and its implications for space weather forecasting, especially when weak solar wind drivers lead to severe storms. i am applying for The 8th Asia-Oceania Space Weather Alliance Workshop (AOSWA 2025) under session 6. I have to submit an abstract for the oral talk. Above is the abstract of my paper. Please form an abstract for the AOSWA 2025 ChatGPT said: Based on your provided paper abstract and the theme of Session 6: General Topics on Space Weather, here's a well-crafted abstract tailored for AOSWA 2025 submission: Title: Unexpected Geoeffectiveness of a Slow ICME: The 25 August 2018 Geomagnetic Storm and the Role of Planar Magnetic Structures Abstract: On 25 August 2018, Earth encountered a slow-moving interplanetary coronal mass ejection (ICME) linked to a CME launched on 20 August. Despite its weak solar wind properties—velocity below 440 km/s, magnetic field strength under 20 nT, and dynamic pressure less than 8 nPa—the ICME triggered an intense geomagnetic storm, with SYM-H dropping below −200 nT. Intriguingly, no sudden storm commencement (SSC) was observed. Instead, the storm was driven by a prolonged (~13 hours) southward interplanetary magnetic field (IMF), suggesting an internal ICME structural origin. Our analysis indicates that a trailing high-speed stream (HSS) compressed the ICME’s rear flank, enhancing the magnetic field and plasma density, and suppressing its expansion. This compression led to the formation of a coherent planar magnetic structure (PMS) within the ICME, which sustained strong southward IMF conditions. Such PMSs are known to couple efficiently with Earth’s magnetosphere, enhancing geoeffectiveness. Magnetopause standoff distances were reduced below 7 RE, and SuperMAG indices revealed pronounced local time asymmetries, indicating significant inner magnetospheric disturbances. These findings emphasize the critical role of ICME internal structure and solar wind interactions in driving unexpected severe space weather, and highlight the importance of accounting for such effects in forecasting models, particularly during periods of weak solar wind drivers. Let me know if you'd like to shorten it to meet a specific word/character limit, or if you want it tailored to include your research institution or co-authors. You said: remove - ChatGPT said: Here is the revised AOSWA 2025 abstract with hyphens removed: Title: Unexpected Geoeffectiveness of a Slow ICME: The 25 August 2018 Geomagnetic Storm and the Role of Planar Magnetic Structures Abstract: On 25 August 2018, Earth encountered a slow moving interplanetary coronal mass ejection (ICME) linked to a CME launched on 20 August. Despite its weak solar wind properties—velocity below 440 km/s, magnetic field strength under 20 nT, and dynamic pressure less than 8 nPa—the ICME triggered an intense geomagnetic storm, with SYM H dropping below 200 nT. Intriguingly, no sudden storm commencement (SSC) was observed. Instead, the storm was driven by a prolonged (~13 hours) southward interplanetary magnetic field (IMF), suggesting an internal ICME structural origin. Our analysis indicates that a trailing high speed stream (HSS) compressed the ICME’s rear flank, enhancing the magnetic field and plasma density, and suppressing its expansion. This compression led to the formation of a coherent planar magnetic structure (PMS) within the ICME, which sustained strong southward IMF conditions. Such PMSs are known to couple efficiently with Earth’s magnetosphere, enhancing geoeffectiveness. Magnetopause standoff distances were reduced below 7 RE, and SuperMAG indices revealed pronounced local time asymmetries, indicating significant inner magnetospheric disturbances. These findings emphasize the critical role of ICME internal structure and solar wind interactions in driving unexpected severe space weather, and highlight the importance of accounting for such effects in forecasting models, particularly during periods of weak solar wind drivers.