Identification

Title

How changes in the tilt angle of the geomagnetic dipole affect the coupled magnetosphere-ionosphere-thermosphere system

Abstract

The orientation of the Earth's magnetic field has changed dramatically during the geological past. We have investigated the effects of changes in dipole tilt angle on the magnetosphere, ionosphere, and thermosphere, using the Coupled Magnetosphere-Ionosphere-Thermosphere (CMIT) model. The dipole tilt angle modulates the efficiency of solar wind-magnetosphere coupling, by influencing the diurnal variation in the angle μ between the dipole axis and the GSM z axis. This influences how much Joule heating occurs at high magnetic latitudes. The dipole tilt angle also controls the geographic distribution of the Joule heating, as it determines the geographic latitude of the magnetic poles. Changes in the amount and distribution of Joule heating with tilt an`gle produce further changes in temperature and neutral winds. The latter affect the O/N₂ ratio, which in turn modifies the peak electron density of the F₂ layer, NmF₂. All these effects are most important when the Interplanetary Magnetic Field (IMF) is southward, while being almost negligible under northward IMF. However, a change in dipole tilt also changes the inclination of the magnetic field, which affects the vertical component of ionospheric plasma diffusion along the magnetic field, regardless of the IMF direction. Changes in vertical plasma diffusion are responsible for ~2/3 of the changes in NmF₂ and most of the low to midlatitude changes in hmF₂ under southward IMF and for most of the changes in both variables under northward IMF. Thermal contraction may be responsible for high-latitude decreases in hmF₂ with increasing tilt angle under southward IMF.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7222vk5

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

2012-10-12T00:00:00Z

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