Preconditioning of Interplanetary Space Due to Transient CME Disturbances

• Published in: The Astrophysical journal Vol. 835; no. 2; pp. 141 - 146
• Main Authors: Temmer, M., Reiss, M. A., Nikolic, L., Hofmeister, S. J., Veronig, A. M.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.02.2017; IOP Publishing
• Subjects: Astrophysics; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Charged particles; COMPARATIVE EVALUATIONS; Coronal holes; Coronal mass ejection; DISTURBANCES; Error analysis; FORECASTING; HELIOSPHERE; High speed; INTERPLANETARY SPACE; MASS; PLASMA; Preconditioning; Solar activity; Solar corona; SOLAR WIND; Solar wind models; Solar wind velocity; solar-terrestrial relations; Space weather; Standard error; STREAMS; SUN; Sun: coronal mass ejections (CMEs); Sun: heliosphere; VELOCITY; Weather forecasting; Wind models; Wind speed
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/835/2/141

Interplanetary space is characteristically structured mainly by high-speed solar wind streams emanating from coronal holes and transient disturbances such as coronal mass ejections (CMEs). While high-speed solar wind streams pose a continuous outflow, CMEs abruptly disrupt the rather steady structure, causing large deviations from the quiet solar wind conditions. For the first time, we give a quantification of the duration of disturbed conditions (preconditioning) for interplanetary space caused by CMEs. To this aim, we investigate the plasma speed component of the solar wind and the impact of in situ detected interplanetary CMEs (ICMEs), compared to different background solar wind models (ESWF, WSA, persistence model) for the time range 2011-2015. We quantify in terms of standard error measures the deviations between modeled background solar wind speed and observed solar wind speed. Using the mean absolute error, we obtain an average deviation for quiet solar activity within a range of 75.1-83.1 km s−1. Compared to this baseline level, periods within the ICME interval showed an increase of 18%-32% above the expected background, and the period of two days after the ICME displayed an increase of 9%-24%. We obtain a total duration of enhanced deviations over about three and up to six days after the ICME start, which is much longer than the average duration of an ICME disturbance itself (∼1.3 days), concluding that interplanetary space needs ∼2-5 days to recover from the impact of ICMEs. The obtained results have strong implications for studying CME propagation behavior and also for space weather forecasting.