Scale-resolved phase coherence analysis of hemispheric sunspot activity: a new look at the north-south asymmetry

R. Donner, M. Thiel

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

Aims. The sunspot activity on both solar hemispheres is known to show time intervals of different phase relationships. In this letter, we introduce an advanced statistical framework that allows an appropriate analysis of these relationships.

Methods. We combine wavelet analysis with statistical measures of phase coherence to obtain well-defined phase differences in dependence on the selected oscillation period.

Results. Our approach characterises the temporally varying phase difference of the hemispheric sunspot activity over the past 130 years, which is a major contribution to the north-south asymmetry. Coherent phase variables are found to exist for a frequency band with periodicities around the dominating 11-year cycle. We observe significant continuous long-term variability of interhemispheric phase shifts, which is not reproduced by solar activity records from previous centuries.

Original languageEnglish
Pages (from-to)L33-L36
Number of pages4
JournalAstronomy & Astrophysics
Volume475
Issue number3
DOIs
Publication statusPublished - 1 Dec 2007

Keywords

  • sunspots
  • sun activity
  • solar activity
  • synchronization
  • locking
  • systems
  • sun

Cite this

Scale-resolved phase coherence analysis of hemispheric sunspot activity : a new look at the north-south asymmetry. / Donner, R.; Thiel, M.

In: Astronomy & Astrophysics, Vol. 475, No. 3, 01.12.2007, p. L33-L36.

Research output: Contribution to journalArticle

@article{0e4a4e5040914354976970e14b47eedb,
title = "Scale-resolved phase coherence analysis of hemispheric sunspot activity: a new look at the north-south asymmetry",
abstract = "Aims. The sunspot activity on both solar hemispheres is known to show time intervals of different phase relationships. In this letter, we introduce an advanced statistical framework that allows an appropriate analysis of these relationships.Methods. We combine wavelet analysis with statistical measures of phase coherence to obtain well-defined phase differences in dependence on the selected oscillation period.Results. Our approach characterises the temporally varying phase difference of the hemispheric sunspot activity over the past 130 years, which is a major contribution to the north-south asymmetry. Coherent phase variables are found to exist for a frequency band with periodicities around the dominating 11-year cycle. We observe significant continuous long-term variability of interhemispheric phase shifts, which is not reproduced by solar activity records from previous centuries.",
keywords = "sunspots, sun activity, solar activity, synchronization, locking, systems, sun",
author = "R. Donner and M. Thiel",
year = "2007",
month = "12",
day = "1",
doi = "10.1051/0004-6361:20078672",
language = "English",
volume = "475",
pages = "L33--L36",
journal = "Astronomy & Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",
number = "3",

}

TY - JOUR

T1 - Scale-resolved phase coherence analysis of hemispheric sunspot activity

T2 - a new look at the north-south asymmetry

AU - Donner, R.

AU - Thiel, M.

PY - 2007/12/1

Y1 - 2007/12/1

N2 - Aims. The sunspot activity on both solar hemispheres is known to show time intervals of different phase relationships. In this letter, we introduce an advanced statistical framework that allows an appropriate analysis of these relationships.Methods. We combine wavelet analysis with statistical measures of phase coherence to obtain well-defined phase differences in dependence on the selected oscillation period.Results. Our approach characterises the temporally varying phase difference of the hemispheric sunspot activity over the past 130 years, which is a major contribution to the north-south asymmetry. Coherent phase variables are found to exist for a frequency band with periodicities around the dominating 11-year cycle. We observe significant continuous long-term variability of interhemispheric phase shifts, which is not reproduced by solar activity records from previous centuries.

AB - Aims. The sunspot activity on both solar hemispheres is known to show time intervals of different phase relationships. In this letter, we introduce an advanced statistical framework that allows an appropriate analysis of these relationships.Methods. We combine wavelet analysis with statistical measures of phase coherence to obtain well-defined phase differences in dependence on the selected oscillation period.Results. Our approach characterises the temporally varying phase difference of the hemispheric sunspot activity over the past 130 years, which is a major contribution to the north-south asymmetry. Coherent phase variables are found to exist for a frequency band with periodicities around the dominating 11-year cycle. We observe significant continuous long-term variability of interhemispheric phase shifts, which is not reproduced by solar activity records from previous centuries.

KW - sunspots

KW - sun activity

KW - solar activity

KW - synchronization

KW - locking

KW - systems

KW - sun

U2 - 10.1051/0004-6361:20078672

DO - 10.1051/0004-6361:20078672

M3 - Article

VL - 475

SP - L33-L36

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

IS - 3

ER -