Identification

Title

Effect of IMF By on thermospheric composition at high and middle latitudes: 2. Data comparisons

Abstract

The strength and orientation of the interplanetary magnetic field (IMF) has a strong effect on the high-latitude plasma convection pattern, thereby influencing the speed and direction of polar thermospheric winds. The possibility of similar IMF control over the compositional response of the thermosphere during geomagnetic disturbances has not been fully investigated. This study finds that the y-component of the IMF (IMF Βy) exerts significant control over the development and subsequent equatorward transport of composition disturbances during periods of heightened geomagnetic activity. This is determined using the NCAR-TIMEGCM to simulate the thermospheric conditions during the first 3 weeks far-ultraviolet (FUV) imaging operations of the Dynamics Explorer 1 (DE-1) mission in 1981. The images reveal changes in the relative thermospheric column abundance of O versus N₂ (ΣO/N₂). These changes are reproduced by the model, incorporating variable IMF strength and orientation as inputs. It is found that simple reversal of IMF Βγ leads to subsequent changes in ΣO/N₂ at middle latitudes by as much as 30%. This is a manifestation of the effect identified in the companion to this report (Crowley et al., 2006). The study confirms the hypothesis of Immel et al. (1997) that IMF-Βγ effects on middle-latitude thermospheric composition are important, though more complex than expected. Contrary to previous predictions, early morning local times are shown to be more likely to suffer large decreases in ΣO/N₂ when Βγ is negative. However, the overall magnitude of high-latitude Joule heating is found to be greater when Βy is positive.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7zk5gzx

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

2006-10-19T00:00:00Z

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