Identification

Title

WINDII observations and TIME-GCM simulations of O(¹S) polar spirals during geomagnetic disturbances

Abstract

The daytime O(¹S) emission at 557.7 nm observed at 250 km with the Wind Imaging Interferometer (WINDII) is dominantly excited by photoelectron impact on atomic oxygen, so the volume emission rate is normally a measure of the atomic oxygen concentration. Daily polar maps of the 250 km volume emission rate during geomagnetic disturbances display polar spirals extending out of the auroral region and down to the equator. Since the local time is fixed for a given latitude for a single day, the spiral maps form a spatio-temporal pattern in which the longitudinal variations cannot be distinguished from those in universal time. Simulations for 2 January 1993 implemented with the National Center for Atmospheric Research Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM) using the equivalent satellite perspective show a remarkably similar spiral pattern. Hourly universal time simulations reveal a rapid equatorward expansion of the spirals during this modest geomagnetic event of Kp = 4.7, which are mirrored in the meridional and vertical winds. Simulations of the electron density show that the emission within the spirals is caused by the recombination of O₂+ ions with electrons, and not the atomic oxygen enhancement itself. All of this strongly suggests that the spirals are in fact large-scale Traveling Ionospheric Disturbances (TIDs), and comparisons of the WINDII data made with TID observations reported in the literature, including those made on the same day, support this conclusion. The TIME-GCM simulations suggest that a component of the spirals originates in the lower atmosphere and appears at thermospheric heights.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7pc3383

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

2013-05-28T00:00:00Z

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