Abstract
The chromospheric network extended to the transition region as the solar EUV network disperses at the coronal level. The EUV emission lines from the transition region give information about different atmospheric heights. The network properties have been obtained from the daily spectroscopic data from the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SOHO) in two lines He i 584.5 Å and O v 630 Å. The synoptic changes in the line intensity, skewness of intensity distribution, mean contrast and network index with respect to the sunspot cycle were studied for a period of 11 years from 1996 to 2006. We have obtained the cross correlation of the monthly average of these quantities with the monthly sunspot number. The mean intensity and skewness of the two lines generally show a positive correlation with the sunspot cycle. The network contrast and network index of the He i shows a definite negative correlation with the sunspot cycle. The negative correlations shown by the He i line are unexpected which could be due to its anomalous behaviour. There are differences in the behaviour of the two lines regarding the time lag with the sunspot cycle and the magnitude of the correlation which is always higher for the He i line. The results have implications to the studies of solar irradiance, magnetic flux transfer and solar atmospheric dynamics.
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Caccin B., Ermolli I., Fofi M., Sambuco A. M. 1998, Sol. Phys., 177, 295B
Chae J., Schuhle U., Lemaire P. 1998, ApJ, 505, 957C
Curdt W., Tian H., Dwivedi B. N., Marsh E. 2008, A&A, 491, 13C
De Pontieu B., McIntosh S. W., Carlsson M., Hansteen V. H., Tarbell T. D., Schrijver C. J., Title A. M., Shine R. A., Tsuneta S., Katsukawa Y., Ichimoto K., Suematsu Y., Shimizu T., Nagata S. 2007, Science, 318, 1574D
Fontenla J. M., Curdt W., Avrett E. H., Harder J. 1999, A&A, 468, 695F
Fuller-Rowell T., Solomon S., Roble R., Viereck R. 2004, Solar variability and its effects on climate, Geophys. Monograph, 141, 341F
Gabriel A. H. 1976, Philos. Trans. R. Soc. London, 281, 339G
Gallagher P. T., Phillips K. J. H., Harra-Murnion L. K., Keenan F. P. 1998, A&A, 335, 733G
Gontikakis C., Peter H., Dara H. C. 2003, A&A, 408, 743
Griffiths N. W., Fisher G. H., Woods D. T., Siegmund O. H. W. 1999, ApJ, 512, 992G
Hansteen V., De Pontieu B., Carlsson M., Lemen J., Title A., Boerner P., Hurl-burt N., Tarbell T. D., Wuelser J. P. et al. 2014, Science, 346, 1255757.
Harrison R. A., Sawyer E. C., Carter M. K., Cruise A. M., Cutler R. M., Fludra A. et al. 1995, Sol. Phys., 162, 233H
Harrison R. A., Fludra A., Pike C. D., Payne J., Thompson W. T., Poland A. I., Breeveld E. R., Culhane J. L., Kjeldseth-moe O., Huber M. C. E., Aschenbach B. 1997, Sol. Phys., 170, 123H
Jordan C., Macpherson K. P., Smith G. R. 2001, MNRAS, 328, 1098J
Klimchuk J. A. 2006, Sol. Phys., 234, 41K
McIntosh S. W., de Pontieu B., Carlsson M., Hansteen V., Boerner P., Goossens M. 2011, Nature, 475, 477M
Parker E. N. 1988, ApJ, 330, 474
Patsourakos S., Vial J. C., Gabriel A. H., Bellamine N. 1999, ApJ, 522, 540P
Pauluhn A., Solanki S. K., Rüedi I., Landi E., Schühle U. 2000, A&A, 362, 737P
Peter H. 2000, A&A, 360, 761
Priyal M., Singh J., Ravindra B., Priya T. G., Amareswari K. 2014, Sol. Phys. 289, 137P
Raju K. P., Singh J. 2002, Sol. Phys., 207, 11R
Raju K. P. 2010, Sol. Phys., 262, 61R
Raju K. P., Singh J. 2014, RAA, 14, 229
Reeves E. M., Foukal P. V., Huber M. C. E. 1974, ApJ, 188L, 27R
Reeves E. M. 1976, Sol. Phys., 46, 53R
Schrijver C. J., Zwaan C., Balke A. C., Tarbell T. D., Lawrence J. K. 1992, A&A, 253L, 1S
Shakeri F., Teriaca L., Solanki S. K. 2015, ApJ, 581A, 51S
Singh J., Belur R., Raju S., Pichaimani K., Priyal M., Gopalan Priya T., Kotikalapudi A. 2012, RAA, 12, 201S
Tian H., Marsch E., Tu C.-Y., Xia L.-D., He J.-S. 2008, A&A, 482, 267
Tian H., Curdt W., Teriaca L., Landi E., Marsch E. 2009, A&A, 505, 307
Tian H., Marsch E., Tu C.-Y., Curdt W., He J.-S. 2010, New Astron. Rev., 54, 13T
Tian H., DeLuca E. E., Cranmer S. R., De Pontieu B., Peter B., Martínez-Sykora J. et al. 2014, Science 346, 1255711
Thompson W. T. 2006, Eur. Space Agency Proc., 617E, 80T
van Ballegooijen A. A., Asgari-Targhi M., Cranmer S. R., DeLuca E. E. 2011 ApJ, 736, 3V
Walsh R. W., Ireland J. 2003, A&A Rev., 12, 1W
Wedemeyer-Bohm S., Scullion E., Steiner O., van der Voort L. R., de La Cruz Rodriguez J., Fedu V. 2012, Nature, 486, 505W
Worden J. R., White O. R., Woods T. N. 2014, ApJ, 496, 998
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The data was provided, courtesy: SOHO/EIT and CDS consortia. SOHO is a project of international co-operation between ESA and NASA. This work was funded by the Department of Science and Technology, Government of India.
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Varghese, B.S., Raju, K.P. & Kurian, P.J. Temporal variations of the solar EUV network properties. J Astrophys Astron 40, 29 (2019). https://doi.org/10.1007/s12036-019-9602-5
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DOI: https://doi.org/10.1007/s12036-019-9602-5