Identification

Title

Sun-as-a-star observations: Evidence for degree dependence of changes in damping of low- ℓ p modes along the solar cycle

Abstract

Aims.We use 9.5-yr of BiSON Sun-as-a-star data to search for dependence of solar-cycle parameter changes on the angular degree, ℓ of the data. The nature of the Sun-as-a-star observations is such that for changes measured at fixed frequency, or for changes averaged across the same range in frequency, any ℓ dependence present carries information on the latitudinal distribution of the agent (i.e., the activity) responsible for those changes. Methods.We split the 9.5-yr timeseries into contiguous 108-d pieces, and determine mean changes in the damping of, power in, and energy supplied to the modes through the solar cycle. We also apply a careful correction to account for the deleterious effects of the ground-based BiSON window function on the results. Results.From our full analysis we obtain a marginally significant result for the damping parameter, where the mean change is found to be weakest at ℓ=0. The other parameters show hints of some dependence in ℓ. Conclusions. Our main conclusion is that the mean fractional solar-cycle change in the ℓ=0 damping rates is approximately 50% smaller than was previously assumed. It had been common practice to use an average over all low-ℓ modes; our downward revision of the radial-mode value has implications for comparisons with models of the global solar cycle changes, which are usually based on a spherically symmetric geometry.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7mp53kc

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

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keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

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East bounding longitude

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Temporal reference

Temporal extent

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End position

Dataset reference date

date type

publication

effective date

2007-03-01T00:00:00Z

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Conformity

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version of format

Constraints related to access and use

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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