Retrieving the EUV solar spectrum from a selected set of lines for space weather purposes: A review ...
Download
1 / 21

Importance of EUV flux for space weather purposes - PowerPoint PPT Presentation


  • 46 Views
  • Uploaded on

Retrieving the EUV solar spectrum from a selected set of lines for space weather purposes: A review of theories, models and experiments J. Lilensten, T. Dudok de Wit, M. Kretzschmar, P.-O. Amblard, S. Moussaoui, J. Aboudarham and F. Auchère (ias). Wavelength.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Importance of EUV flux for space weather purposes' - marina


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Retrieving the EUV solar spectrum from a selected set of lines for space weather purposes: A review of theories, models and experiments

J. Lilensten, T. Dudok de Wit, M. Kretzschmar, P.-O. Amblard, S. Moussaoui, J. Aboudarham and F. Auchère (ias)

ESWW4, Brussels, Novembre 2006


Wavelength lines for space weather purposes: A review of theories, models and experiments

  • Importance of EUV flux for space weather purposes

  • Influences the near space environment (ionosphere / thermosphere)

ESWW4, Brussels, Novembre 2006


  • Result lines for space weather purposes: A review of theories, models and experiments (amongst other phenomena) in

  • Dilatation of the thermosphere (density may increase by a factor of 10 at the altitude of the International Space Station)

  • rapid variations, creations of small scale disturbances, winds

ESWW4, Brussels, Novembre 2006


Variations are not linear lines for space weather purposes: A review of theories, models and experiments

Pap and Frölich, 1999; Nesme-Ribes and Thuiller, 2000

ESWW4, Brussels, Novembre 2006


Their characteristic variation times range from the second to several years

14 July 1998

27 days

CELIAS/SEM experiment, Bochsler, 1999

ESWW4, Brussels, Novembre 2006


F79050, f10.7 = 243

SC#21REF, f10.7 = 70

C++

O5+

He

O4+

Mg10+

O3+

O5+

O++

Ne6+

He+ et Si9+

Lyman b

Fe14+

N3+et Ne7+

O3+etMg9+

Si10+ et He+

Torr and Torr (1985)

ESWW4, Brussels, Novembre 2006


SERF / HFG to several years

Torr, M.R., and D.J. Torr, J. Geophys. Res.90, 6675-6678, 1985

EUV / SOLAR 2000

Tobiska, W. K. and F. Eparvier, Sol. Phys., 177, 147-159, 1998

EUVAC / HEUVAC

Richards, P. G., J. A. Fennelly, and D.J. Torr, J. Geophys. Res.99, 8981-8992, 1994

P. G. Richards, T. N. Woods, and W. K. Peterson, Adv. Spa. Res., 37, 315-322,2006

NRLEUV

Lean et al, J. Geophys. Res.108, 1059, 2003

Warren et al., J. Geophys. Res.106, 15 745, 2001

Other:

Nusinov A. A., models for prediction of EUV and W-ray solar radiation based on 10.7 cm radio emission, Ed. R.F. Donnely, NOAA ERL, 1992

ESWW4, Brussels, Novembre 2006


Year to several years

  • 2) Existing models for Aeronomy

    • . Based on indices (Ri, f10.7, Mg …) or proxies (E10.7, X10.7, Iu …)

    • (see poster P2.7, Menvielle)

ESWW4, Brussels, Novembre 2006


T. Dudok de Witet al., Which solar EUV proxies are best for reconstructing the solar EUV irradiance?,submitted to Adv. Spac. Res., 2006

ESWW4, Brussels, Novembre 2006


Schmidtke et al., Tiger program, Adv. Sp. Res., 10, 1553-1559, 2002

ESWW4, Brussels, Novembre 2006


Today : only to several years Solar Extreme Ultraviolet Experiment (SEE) onboard TIMED (NASA)

  • EUV Grating Spectrograph (EGS)

    • 25 à 200 nm

    • 0.4 nm spectral resolution.

EGS

  • XUV Photometer System (XPS)

    • 0.1 to 35 nm in 12 spectral bands

XPS

Woods, et al., Solar EUV Experiment (SEE): mission overview and first results. J. Geophys. Res., 110, 1312-1336, 2005.

ESWW4, Brussels, Novembre 2006


  • Retrieve the flux variation through their effects

  • On electron density profiles (Mikhailov and Schlegel, Ann. Geoph., 18, 1164 – 1171, 2000)

  • On the E region critical frequency (Nusinov, Adv. Space Res., 37, 426-432, 2006)

  • On the thermospheric emission (Singh and Tyagi, Adv. Space Res., 30, 255è-2562, 2002)

  • On wind or temperatures (Zhang et al., Geoph. Res. Lett., 29, 10.029/2001GL013579, 2002)

ESWW4, Brussels, Novembre 2006


ESWW4, Brussels, Novembre 2006


Reduce the solar spectrum to a limited (3) set of characteristic spectra: very promissing method through positive source separation

SEE (TIMED) : reconstruction < 2%

Quiet sun contribution?

Active zone contribution?

Hot lines contribution?

ESWW4, Brussels, Novembre 2006


Physics through Differential Emission Measure: 6 to 10 lines are necessary

See poster P6.4, Kretzschmar et al.

M. Kretzschmar et al., Retrieving the Whole Solar EUV Flux from 6 Irradiance Line Measurements, Advances in Space Research, 37, 341–346, 2006

ESWW4, Brussels, Novembre 2006


Use statistics (Singular Value Decomposition): 6 to 10 lines are necessary. Same conclusion through 2 totally different approaches

T. Dudok de Wit, et al., Retrieving the solar EUV spectrum from a reduced set of spectral lines, Annales Geophysicae, 23, 3055–3069, 2005

ESWW4, Brussels, Novembre 2006


How to choose the lines to be observed? are necessary. Same conclusion through 2 totally different approaches

Statistical analysis of TIMED/SEE data.

Using two

years of daily EUV spectra and classification techniques,

Dendrogram of 38 spectral lines using an average distance

linkage between all lines.

ESWW4, Brussels, Novembre 2006


This table allows to select the best set of lines to observe in order to reconstruct the total flux with the best accuracy.

The relative global error for the best combination of 6 lines yields to 3.7% and less than 0.25% with 10 lines

ESWW4, Brussels, Novembre 2006


However, the « best » set may depend on the application. An example : the ionosphere

How to choose an observed set of solar lines for aeronomy driven applications, J. Lilensten et al., submitted to Ann. Geoph., 2006

ESWW4, Brussels, Novembre 2006


Using a multidimensional scaling technique An example : the ionosphere :

H I at 102.572 nmCIII at 97.702 nmOV at 62.973 nmHeI at 58.433 nmFeXV at 28.415 nmHeII at 30.378 nm

Allows to retrieve the full solar spectrum with a relative global error of 6.8 % and still fulfill ionospheric physics requirements.

ESWW4, Brussels, Novembre 2006


Near future: LYRA, the Solar VUV radiometer on-board PROBA II

J.-F. Hochedez et al., Adv. Space Res., 37, Iss 2, 303-312, 2006

http://lyra.oma.be/index.php

1/ Lyman-alpha (115-125 nm)

2/ the 200-220 nm range

3/ Al filter channels (17-70 nm

4/ MgF2 windows (120-220 nm),

And EVE on-board SDO

http://lasp.colorado.edu/eve/eve_home.html

ESWW4, Brussels, Novembre 2006


ad