The Solar Feature Catalogues for sunspots and active regions measured with
SOHO/MDI instrument and Ca II K3 spectroheliograph of the Paris-Meudon Obser-
vatory are analyzed with the automated classification technique for sunspot groups
and active region polarities. We report the first classification results for daily vari-
ations of tilt angles (normal and trigonometric ones) in sunspot groups (SG) and
active (AR) regions in the cycle 23. The average normal tilts are presented for every
year at the ascending and descending phases of the cycle 23 which are similar to
those deduced by other authors for the cycles 19-22. The normal tilts of both the
sunspot groups and active regions are shown to increase in the ascending phase and
a decrease in the descending phase. Similar to SG and AR areas, the trigonometric
tilts are shown to have the noticeable North-South asymmetry with the Southern
hemisphere dominant in the selected ascending and descending periods. The nor-
mal tilt variations with latitude follow Joy?s law revealing a periodicity along the
meridian of about 10 and reaching the maximum of 14 at the latitude of about
32 corresponding to the top of the ?royal zone? where the sunspots appear. The
variations of polarity separation with a latitude are in an anti-phase with those of
the tilts reaching a maximum at the latitude of 35 and showing a small positive
separation for the groups/active regions in a vicinity of the average tilts ?40. The
ratio R of the polarity separation to the trigonometric tilt fits the linear function
of a latitude ' as R = −0.0213' − 0.1245 confirming positive separation for the
polarities of active regions with the average tilts, or the dominance of activity in
the Southern hemisphere activity, for the selected period of observations.
Authors: Zharkova V.V. and Zharkov S.I.
Projects: SoHO-MDI
Publication Status: Adv.Space Res., 2008 in press
Last Modified: 2008-02-07 09:22
The Solar Feature Catalogues for sunspots and active regions measured with SOHO/MDI instrument and Ca II K3 spectroheliograph of the Paris-Meudon Observatory are analyzed with the automated classification technique for sunspot groups and active region polarities. We report the first classification results for daily variations of tilt angles (normal and trigonometric ones) in sunspot groups (SG) and active (AR) regions in the cycle 23. The average normal tilts are presented for every year at the ascending and descending phases of the cycle 23 which are similar to
those deduced by other authors for the cycles 19-22. The normal tilts of both the sunspot groups and active regions are shown to increase in the ascending phase and a decrease in the descending phase. Similar to SG and AR areas, the trigonometric tilts are shown to have the noticeable North-South asymmetry with the Southern hemisphere dominant in the selected ascending and descending periods. The normal tilt variations with latitude follow Joy's law revealing a periodicity along the meridian of about 10° and reaching the maximum of 14° at the latitude of about 32° corresponding to the top of the ''royal zone'' where the sunspots appear. The variations of polarity separation with a latitude are in an anti-phase with those of the tilts reaching a maximum at the latitude of 35°and showing a small positive separation for the groups/active regions in a vicinity of the average tilts ±40°. The ratio R of the polarity separation to the trigonometric tilt fits the linear function of a latitude φ as R = −0.0213φ − 0.1245 confirming positive separation for the polarities of active regions with the average tilts, or the dominance of activity in the Southern hemisphere activity, for the selected period of observations.
Authors: Zharkova V.V. and Zharkov S.I.
Projects: SoHO-MDI
Publication Status: Adv.Space Res., 2008 in press
Last Modified: 2008-02-07 12:43
The observed phase relations between the weak background solar magnetic (poloidal) field and strong magnetic field assocciated wtih sunspots (toroidal field) measured at different latitudes are presented. For measurements of the solar magnetic field (SMF) the low-resolution images obtained from Wilcox Solar Observatory (WSO) are used while sunspot magnetic field was taken from the Solar
Feature Catalogues utilizing the SOHO/MDI fulldisk magnetograms. The quasi-3D latitudinal distributions of sunspot areas and magnetic elds obtained for 30
latitudinal bands (15 in the northern and 15 in the southern hemispheres) within the whole mu-hemispheres in longitudes are correlated with those of the background SMF. The sunspot areas in all latitudinal zones (averaged with a sliding one-year filter) reveal a strong positive correlation with the absolute SMF in the same zone
appearing rst with a zero timelag and repeating with a two three year time lag through the whole period of observations. The residuals of the sunspot areas averaged
by one year and those by four years are also shown to have a well defined periodic structure visible in every two - three years close to pi/4 with the maxima occurring at -40 and +40 degrees in latitude and the drifts during this period either towards the Equator or the Poles depending on the latitude of sunspot occurrence. This phase relation between
poloidal and toroidal field throughout the whole cycle is discussed in association with both the symmetric and asymmetric components of the background SMF and
relevant predictions by the solar dynamo models.
Authors: Zharkov S.I., Gavryuseva,E. and Zharkova V.V
Projects: SoHO-MDI
Publication Status: Solar Physics, in press
Last Modified: 2008-02-07 09:22
The observed phase relations between the weak background solar magnetic (poloidal) field and strong magnetic field assocciated wtih sunspots (toroidal field) measured at different latitudes are presented. For measurements of the solar magnetic field (SMF) the low-resolution images obtained from Wilcox Solar Observatory (WSO) are used while sunspot magnetic field was taken from the Solar Feature Catalogues utilizing the SOHO/MDI full disk magnetograms. The quasi-3D latitudinal distributions of sunspot areas and magnetic fields obtained for 30 latitudinal bands (15 in the northern and 15 in the southern hemispheres) within the whole mu-hemispheres in longitudes are correlated with those of the background SMF. The sunspot areas in all latitudinal zones (averaged with a sliding one-year filter) reveal a strong positive correlation with the absolute SMF in the same zone appearing first with a zero timelag and repeating with a two-three year time lag through the whole period of observations. The residuals of the sunspot areas averaged by one year and those by four years are also shown to have a well defined periodic structure visible in every two-three years close to π/4 with the maxima occurring at -40 and +40 degrees in latitude and the drifts during this period either towards the Equator or the Poles depending on the latitude of sunspot occurrence. This phase relation between poloidal and toroidal field throughout the whole cycle is discussed in association with both the symmetric and asymmetric components of the background SMF and relevant predictions by the solar dynamo models.
Authors: Zharkov S.I., Gavryuseva,E. and Zharkova V.V
Projects: SoHO-MDI
Publication Status: Solar Physics, in press
Last Modified: 2008-02-07 09:45
The observed phase relations between the weak background solar magnetic (poloidal) field and strong magnetic field associated with sunspots (toroidal field) measured at different latitudes are presented. For measurements of the solar magnetic field (SMF) the low-resolution images obtained from Wilcox Solar Observatory (WSO) are used while sunspot magnetic field was taken from the Solar Feature Catalogues utilizing the SOHO/MDI full disk magnetograms. The quasi-3D latitudinal distributions of sunspot areas and magnetic fields obtained for 30 latitudinal bands (15 in the northern and 15 in the southern hemispheres) within the whole µ-hemispheres in longitudes are correlated with those of the background SMF. The sunspot areas in all latitudinal zones (averaged with a sliding one-year filter) reveal a strong positive correlation with the absolute SMF in the same zone appearing first with a zero timelag and repeating with a two-three year time lag through the whole period of observations. The residuals of the sunspot areas averaged by one year and those by four years are also shown to have a well defined periodic structure visible in every two-three years close to π/4 with the maxima occurring at -40 and +40 degrees in latitude and the drifts during this period either towards the Equator or the Poles depending on the latitude of sunspot occurrence. This phase relation between poloidal and toroidal field throughout the whole cycle is discussed in association with both the symmetric and asymmetric components of the background SMF and relevant predictions by the solar dynamo models.
Authors: Zharkov S.I., Gavryuseva,E. and Zharkova V.V
Projects: SoHO-MDI
Publication Status: Solar Physics, in press
Last Modified: 2008-02-07 09:47
The observed phase relations between the weak background solar magnetic
(poloidal) eld and strong magnetic eld associated with sunspots (toroidal
eld) measured at dierent latitudes are presented. For measurements of the solar
magnetic eld (SMF) the low-resolution images obtained from Wilcox Solar Observatory
(WSO) are used while sunspot magnetic eld was taken from the Solar
Feature Catalogues utilizing the SOHO/MDI fulldisk magnetograms. The quasi-
3D latitudinal distributions of sunspot areas and magnetic elds obtained for 30
latitudinal bands (15 in the northern and 15 in the southern hemispheres) within the whole -hemispheres in longitudes are correlated with those of the background SMF. The sunspot areas in all latitudinal zones (averaged with a sliding one-year lter) reveal a strong positive correlation with the absolute SMF in the same zone
appearing rst with a zero timelag and repeating with a two three year time lag
through the whole period of observations. The residuals of the sunspot areas averaged
by one year and those by four years are also shown to have a well dened periodic
structure visible in every two three years close to =4 with the maxima occurring
at
Authors: Zharkov S.I., Gavryuseva,E. and Zharkova V.V
Projects: SoHO-MDI
Publication Status: Solar Physics, in press
Last Modified: 2008-02-07 07:55