Identification

Title

Seasonal and longitudinal variations of the solar quiet (Sq) current system during solar minimum determined by CHAMP satellite magnetic field observations

Abstract

Vector magnetometer observations from the Challenging Minisatellite Payload (CHAMP) satellite are used to determine the solar quiet (Sq) current system during the recent solar minimum. Observations from 2006 to 2008 are combined, and after removal of a main field model and accounting for field-aligned currents, the longitudinal and seasonal variation of the Sq currents are determined through the method of spherical harmonic analysis. Comparison with Sq currents derived from ground-based magnetometers in the African/European longitude sector reveals similar amplitudes and seasonal variations, indicating that the CHAMP observations can reliably determine the Sq current system. The seasonal variation is consistent with prior observations during solar minimum conditions and in the Northern Hemisphere exhibits a primarily annual variation with peak currents during local summer. The seasonal variation in the Southern Hemisphere is characterized by a semiannual variation with the maxima occurring around the equinoxes. Significant longitudinal variations are also observed, and they display a seasonal variability. During Northern Hemisphere summer, the predominant feature at local noon is a wave number 1 variation in longitude. During the remainder of the year, a wave 3 longitudinal structure is observed at this local time. The longitudinal variations are considered to be due to a combination of the orientation and strength of the geomagnetic field as well as the tidal winds in the lower thermosphere. Variations in tidal winds due to nonmigrating tides may influence the dynamo-generated electric fields and currents, resulting in the observed longitudinal variations of the Sq current function.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d79g5nfb

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

2011-04-21T00:00:00Z

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