Identification

Title

Photoelectrons as a tool to evaluate spectral variations in solar EUV irradiance over solar cycle timescales

Abstract

There is limited information about the relative magnitude of the spectral variations in the ionizing component of solar irradiance on solar cycle timescales. We found that the Thermosphere, Ionosphere, Mesosphere, Energetics, and Dynamics (TIMED)/Solar Extreme Ultraviolet Experiment (SEE) Version 9 irradiance values predict relatively more ionospheric heating at solar minimum than those from Version 8. These changes have direct impacts on solar cycle timescale variations in ionospheric and thermospheric energy inputs derived from them. Photoelectron observations from the Fast Auroral Snapshot (FAST) satellite obtained from 2002 to 2008 are used with solar irradiance data, photoelectron flux models, and models of solar irradiance to examine the solar cycle variations of irradiance in the 4-27 nm range derived from the XPS sensor in the TIMED/SEE instrument suite. Good (±50%) agreement is found between daily photoelectron observations and model predictions. The largest differences between observed and modeled fluxes are in the 4-10 nm range, where the Fast Auroral Snapshot data show that the SEE Version 9 irradiances are systematically low. Our analysis suggests that variation on solar cycle timescales in the TIMED/SEE Version 9 and Flare Irradiance Spectral Model irradiance derived from them are systematically low in the 18-27 nm region. Because of uncertainties in the absolute value of the observed photoelectron fluxes and solar irradiances, differences between observed and modeled photoelectron fluxes are not sufficient to determine more exactly the magnitude of variation on solar cycle timescales of solar irradiance in the 4-27 nm region. These suggestions can be confirmed by higher spectral resolution observations that will be made on the Solar Dynamics Observatory mission.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d71v5fzw

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

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South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2009-10-13T00:00:00Z

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