Identification

Title

The effect of ∼27 day solar rotation on ionospheric F₂ region peak densities (NmF₂)

Abstract

Ionospheric F² region peak electron densities (NmF²) observed from 11 ionosonde stations in the East Asian-Australian sector from 1969 to 1986 have been used to investigate the effect of ∼27 day solar rotation on the ionosphere. These stations were located from the magnetically equatorial regions to the middle latitudes in both hemispheres. We found that, averaged over all stations and for 18 years, the normalized standard deviation of the midday ∼27 day variations of NmF₂ was 8% and that of the midnight variations was 10%. We applied different data analysis methods, including Fourier transform, band-pass filter, and multiple linear regression analysis, to determine quantitatively the sources of the observed ∼27 day variations of NmF₂ and their relative contributions to these variations. Our results show that the ∼27 day variations in solar radiation and geomagnetic activity, caused by solar rotation, are the main drivers of the ionospheric ∼27 day variations. They accounted for more than 85% of the variations seen in the NmF₂ ∼27 day variation, and their contributions became about 95% at higher latitudes. At geomagnetically low latitudes, the contribution of the ∼27 day variation in solar EUV radiation was greater than that of the ∼27 day variation in geomagnetic activity. However, the contribution from geomagnetic activity became more significant and was even larger than the contribution of solar radiation at higher latitudes, especially at midnight. At all latitudes the correlation between the ∼27 day variations of NmF₂ and solar radiation was evidently positive, whereas that between NmF₂ and geomagnetic activity was positive at geomagnetically low latitudes and became negative at higher middle latitudes. We did not found large seasonal or solar cycle changes in the ∼27 day variations of NmF₂. These variations, however, did show significant differences between the two hemispheres.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d74t6k1d

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

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

2012-03-06T00:00:00Z

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

Copyright 2012 American Geophysical Union.

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

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 date

2025-12-26T04:03:03.008370

Metadata language