Identification

Title

A numerical study of the high latitudinal ion-neutral coupling time scale under disturbed conditions

Abstract

When solar wind and interplanetary magnetic field (IMF) disturb, thermospheric winds change accordingly. Among the momentum forces driving high-latitude thermospheric winds, ion drag is supposed to greatly affect wind variations through ion-neutral coupling when abrupt and strong changes in ion drifts occur. However, due to the great inertia of thermospheric winds it needs a certain period of time for the wind changes to be prominent both in speed and direction. How long the neutral winds take to change from one steady state to another through the ion-neutral coupling process is currently still a controversial issue. In this paper, we examine the high latitudinal ion-neutral coupling time scale based on the Thermosphere Ionosphere Electrodynamics General Circulation Model simulations, which can determine whether wind variations are dominantly driven by ion drag by analyzing the relative contribution of each momentum force. It is found that the spatial variation of ion-neutral coupling time scale is primarily determined by local electron density, but also varies with neutral density and ion-neutral collision frequency. Simulations during periods of medium solar activity at similar to 250 km altitude show that the ion drag-dominated region is generally located at the dayside convection inverse boundary and the coupling time scale (e-folding time) is similar to 1 hr when IMF By is the dominant component of the IMF and changes direction. Meanwhile, the southward component of IMF Bz enlarges the ion drag-dominated region. When IMF Bz is southward with a large magnitude, ion drag-dominated region is primarily located in the nightside auroral oval with similar to 2 hr coupling time scale.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7vx0mrh

codeSpace

Dataset language

eng

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code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

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Text

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title

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reference date

date type

publication

effective date

2016-01-01T00:00:00Z

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East bounding longitude

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South bounding latitude

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date type

publication

effective date

2024-07-08T00:00:00Z

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Copyright 2024 American Geophysical Union (AGU).

Limitations on public access

None

Responsible organisations

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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

2025-07-10T20:00:25.026318

Metadata language

eng; USA