A1D2.4
Lead Beneficiary: KO
Beneficiaries involved: HVAR, ROB, UNIGRAZ, UOulu
Due Date: month 36
Goal
Exploitation of the new data gathered and derived within SOTERIA project in solar and space-weather studies, and publication of at least four peer-reviewed research papers until the end of the project. We endeavour that the number of all publications including conference presentations will be substantially higher.
Progress so far
Percentage towards the goal of the deliverable: 30%.
HVAR and UNIGRAZ studied the solar rotation in cooperation with people outside SOTERIA. Solar differential rotation was measured by tracing small bright coronal structures (SBCS) in SOHO-EIT images during most of the 23rd solar cycle, in the years 1998-2006. The 28.4 nm EIT channel was used and positions of more than 55000 structures were measured applying an interactive and an improved automatic methods of data reduction. A more differential rotation profile of SBCS than of sunspot groups was found and the rotation velocity of SBCS is very similar to the one obtained by small photospheric magnetic features. Finally, the rotation of coronal structures was compared to the rotation of subphotospheric layers derived from local helioseismology analysis of GONG++ dopplergrams. They also made solar cycle predictions and reconstructions. Applying and combining different methods, the strength and epochs for the next 24th solar cycle are predicted. The combined method consists of the three parts: (i) the calculation of the asymmetry of the ascending and descending solar cycle phases, (ii) the correlation of the relative sunspot numbers in and around solar activity minima with the following activity maxima, and (iii) the method of the autoregressive moving average model (ARMA) applied to the relative sunspot number data measured up to now. The used data sets include yearly, corrected yearly, monthly and smoothed monthly relative sunspot number values. With these combined procedures a lower amplitude of the next solar activity maximum, in comparison with the previous one, is estimated. Also, the periodicity of the solar activity cycle is studied using the cosmogenic C-14 data during the last 10 000 years. The solar activity cycle is found to be on the edge of the chaotic behaviour. We started to use also the Be-10 data for the long-term solar activity analysis.
UOulu has analyzed the longitudinal occurrence of solar X-ray flares observed by GOES satellites using a specially developed dynamic, differentially rotating coordinate system. In this frame, the longitude distribution shows two persistent preferred longitudes separated by about 180 degrees. An improved, global statistical analysis finds the best fitting values for parameters describing the differential rotation of active longitudes of X-ray flares. The new analysis gives systematically higher levels of non-axisymmetry for the longitudinal distribution, and makes the rotation parameters consistent between the three different classes of X-ray flares. The analysis will be continued to compare active longitudes for other forms of solar activity, in particular sunspots.
One paper (HVAR) has been published in Astronomy and Astrophysics so far, one paper (UOulu, to Journal of Atmospheric and Solar-Terrestrial Physics) is in press. Submissions to the JASTP: UOulu (one), ROB (one), KO (two), submissions to the An&Ap: HVAR and UNIGRAZ (two), KO (one). On international conferences eight posters or oral talks related to SOTERIA and/or having SOTERIA in acknowledgements of presentations have been presented so far.
Further cooperation going on within SOTERIA: KO develops a procedure to provide a further input to the International Sunspot Number edited by ROB. This will be a step in intercalibrating and validating solar datasets from quite different sources. Regarding the study of sunspot indices at ROB, the science exploitation work will start soon. After a 1-year delay giving time for the base WP2 catalogs to be assembled and filled, the ROB has now hired for 2 years on SOTERIA funds a post-doc who will start science studies of newly defined photospheric indices by November 2, 2009.
Persons involved
KO: A. Ludmány, T. Baranyi, L. Győri senior scientists, J. Muraközy PhD student and N. Gyenge undergraduate student.
ROB: F. Clette
HVAR: R. Brajša, D. Ruždjak, J. Čalogović
UNIGRAZ: A.Hanslmeier
UOulu: K. Mursula
Suggestions for collaboration
KO and UOulu intends to study long-term variations in geomagnetic activity in comparison with a recently found variability spanning eight solar cycles, as a result of discussions in August, 2009. Further collaborations have been proposed by the representatives of HVAR, KO and UNIGRAZ in October, 2009. They will conduct common investigations on the long-term variations of asymmetries of solar hemispheric cycles, differential rotation and tilt angle behaviour.
