| Autor: |
Tindale, E.1 l.tindale@warwick.ac.uk, Chapman, S.C.1,2, Moloney, N.R.3, Watkins, N.W.1,2,4,5 |
| Předmět: |
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| Zdroj: |
Journal of Geophysical Research. Space Physics. Sep2018, Vol. 123 Issue 9, p7196-7210. 15p. |
| Abstrakt: |
Time series of solar wind variables are bursty in nature. Bursts, or excursions, in the time series of solar wind parameters are associated with various transient structures in the solar wind plasma and are often the drivers of increased space weather activity in Earth's magnetosphere. We define bursts by setting a threshold value of the time series and identifying how often, and for how long, it is exceeded. This allows us to study how the statistical distributions and scaling properties of burst parameters vary over solar cycles 23 and 24. We find that the distributions of burst duration and integrated burst size vary over the solar cycle and between the equivalent phases of consecutive cycles. However, there exists a single power law scaling relation between burst size and duration, with a joint area‐duration scaling exponent α that is independent of the solar cycle. This provides a solar cycle invariant constraint between possible sizes and durations of solar wind bursts that can occur. Plain Language Summary: The solar wind is an outflow of plasma which streams away from the Sun's atmosphere. Because it carries a magnetic field, when it reaches the Earth, it can interact with the terrestrial magnetic field and transfer energy. This space weather interaction is responsible for the northern and southern lights; however, energy deposited by the solar wind can also have significant negative consequences, such as disrupting radio communications and navigation and in extreme cases inducing large enough currents in power grids to cause blackouts. The solar wind and its magnetic field are bursty, and these bursts can cause space weather. We study how the likelihood of bursts varies over the two most recent 11‐year solar activity cycles. The time duration and size of the bursts are found to be related to each other in a manner that does not vary with solar cycle activity, whereas other detailed properties of the bursts do vary. This constrains the size and duration of potentially space weather‐causing bursts that can arrive at the Earth. Key Points: We present the first comparison of solar wind burst statistics between the maxima and minima of two solar cyclesMoments of the burst size and burst duration statistical distributions are solar cycle dependentBurst size and duration are related by a power law relation with a solar cycle‐independent exponent [ABSTRACT FROM AUTHOR] |
| Databáze: |
GreenFILE |
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