Identification

Title

Unusual declining phase of solar cycle 23: Weak semi-annual variations of auroral hemispheric power and geomagnetic activity

Abstract

Seasonal variations of geomagnetic activity during the declining phase of solar cycle 23 (SC23-D, 2002-2007) have been studied using auroral hemispheric power (HP), solar wind and interplanetary magnetic field (IMF) data and the Kp index. The well known semi-annual variations of geomagnetic activity, with peaks occurring during equinoxes, were virtually absent during SC23-D. This makes SC23-D markedly different from previous solar cycles which had clear semi-annual variations. In SC23-D, both Kp and HP had unusual peaks around the December solstice (in years 2003, 2004 and 2006) and August (in years 2004 and 2005), instead of at the equinoxes. These peaks appeared to be associated with solar wind/IMF and the consequent merging electric field peaks in the same periods. Furthermore, the absolute values and relative changes of the Kp index were much smaller in SC23-D than in other solar cycles. The very weak dynamic pressure and southward IMF in SC23-D might also limit the regular modulation effects that contribute to the occurrence of peaks in equinoxes.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d75q4x4d

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2009-11-20T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact