Identification

Title

Determining ULF wave contributions to geomagnetically induced currents: The important role of sampling rate

Abstract

Past studies found that large-amplitude geomagnetically induced current (GIC) related to magnetospheric Ultra Low Frequency (ULF) waves tend to be associated with periods >120 s at magnetic latitudes >60 degrees, with comparatively (a) smaller GIC amplitudes at lower latitudes and shorter wave periods and (b) fewer reports of waves associated with GIC at lower latitudes. ULF wave periods generally decrease with decreasing latitude; thus, we examine whether these trends might be due, in part, to the undersampling of ULF wave fields in commonly available measurements with 60 s sampling intervals. We use geomagnetic field (B), geoelectric field (E), and GIC measurements with 0.5-10 s sampling intervals during the 29-31 October 2003 geomagnetic storm to show that waves with periods <similar to 120 s were present during times with the largest amplitude E and GIC variations. These waves contributed to roughly half the maximum E and GIC values, including during times with the maximum GIC values reported over a 14-year monitoring interval in New Zealand. The undersampling of wave periods <120 s in 60 s measurements can preclude identification of the cause of the GIC during some time intervals. These results indicate (a) ULF waves with periods <= 120 s are an important contributor to large amplitude GIC variations, (b) the use of 0.1-1.0 Hz sampling rates reveals their contributions to B, E, and GIC, and (c) these waves' contributions are likely strongest at magnetic latitudes <60 degrees where ULF waves often have periods <120 s.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7c53qwr

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

2023-05-01T00:00:00Z

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