GUMICS-4 analysis of interplanetary coronal mass ejection impact on Earth during low and typical Mach number solar winds

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Lakka , A , Pulkkinen , T I , Dimmock , A P , Kilpua , E , Ala-Lahti , M , Honkonen , I , Palmroth , M & Raukunen , O 2019 , ' GUMICS-4 analysis of interplanetary coronal mass ejection impact on Earth during low and typical Mach number solar winds ' , Annales Geophysicae , vol. 37 , no. 4 , pp. 561-579 . https://doi.org/10.5194/angeo-37-561-2019

Title: GUMICS-4 analysis of interplanetary coronal mass ejection impact on Earth during low and typical Mach number solar winds
Author: Lakka, Antti; Pulkkinen, Tuija I.; Dimmock, Andrew P.; Kilpua, Emilia; Ala-Lahti, Matti; Honkonen, Ilja; Palmroth, Minna; Raukunen, Osku
Contributor: University of Helsinki, Space Physics Research Group
University of Helsinki, Particle Physics and Astrophysics
University of Helsinki, Department of Physics
Date: 2019-07-11
Language: eng
Number of pages: 19
Belongs to series: Annales Geophysicae
ISSN: 0992-7689
URI: http://hdl.handle.net/10138/304750
Abstract: We study the response of the Earth's magnetosphere to fluctuating solar wind conditions during interplanetary coronal mass ejections (ICMEs) using the Grand Unified Magnetosphere-Ionosphere Coupling Simulation (GUMICS-4). The two ICME events occurred on 15-16 July 2012 and 29-30 April 2014. During the strong 2012 event, the solar wind upstream values reached up to 35 particles cm(-3), speeds of up to 694 km s(-1), and an interplanetary magnetic field of up to 22 nT, giving a Mach number of 2.3. The 2014 event was a moderate one, with the corresponding upstream values of 30 particles cm(-3), 320 km s(-1) and 10 nT, indicating a Mach number of 5.8. We examine how the Earth's space environment dynamics evolves during both ICME events from both global and local perspectives, using well-established empirical models and in situ measurements as references. We show that on the large scale, and during moderate driving, the GUMICS-4 results are in good agreement with the reference values. However, the local values, especially during high driving, show more variation: such extreme conditions do not reproduce local measurements made deep inside the magnetosphere. The same appeared to be true when the event was run with another global simulation. The cross-polar cap potential (CPCP) saturation is shown to depend on the Alfven-Mach number of the upstream solar wind. However, care must be taken in interpreting these results, as the CPCP is also sensitive to the simulation resolution.
Subject: CAP POTENTIAL SATURATION
HIGH-LATITUDE
GEOMAGNETIC-ACTIVITY
PLASMA TRANSPORT
MHD SIMULATION
MAGNETOSPHERE
MODEL
SHOCK
IONOSPHERE
STORMS
115 Astronomy, Space science
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