Solar Magnetic Field Distribution Research Articles

Predict the spatiotemporal distribution of solar magnetic field and understand the evolutionary feature of solar activity

Predict the spatiotemporal distribution of solar magnetic field and understand the evolutionary feature of solar activity

Forecasting solar extreme and far ultraviolet irradiance

A new method is presented to forecast the solar irradiance of selected wavelength ranges within the extreme ultraviolet (EUV) and far ultraviolet (FUV) bands. The technique is similar to a method recently published by Henney et al. (2012) to predict solar 10.7 cm (2.8 GHz) radio flux, abbreviated F10.7, utilizing advanced predictions of the global solar magnetic field generated by a flux transport model. In this and the previous study, we find good correlation between the absolute value of the observed photospheric magnetic field and selected EUV/FUV spectral bands. By evolving solar magnetic maps forward 1 to 7 days with a flux transport model, estimations of the Earth side solar magnetic field distribution are generated and used to forecast irradiance. For example, Pearson correlation coefficient values of 0.99, 0.99, and 0.98 are found for 1 day, 3 day, and 7 day predictions, respectively, of the EUV band from 29 to 32 nm. In the FUV, for example, the 160 to 165 nm spectral band, correlation values of 0.98, 0.97, and 0.96 are found for 1 day, 3 day, and 7 day predictions, respectively. In the previous study, the observed F10.7 signal is found to correlate well with strong magnetic field (i.e., sunspot) regions. Here we find that solar EUV and FUV signals are significantly correlated with the weaker magnetic fields associated with plage regions, suggesting that solar magnetic indices may provide an improved indicator (relative to the widely used F10.7 signal) of EUV and FUV nonflaring irradiance variability as input to ionospheric and thermospheric models.

Forecasting F10.7 with solar magnetic flux transport modeling

A new method is presented here to forecast the solar 10.7 cm (2.8 GHz) radio flux, abbreviated F10.7, utilizing advanced predictions of the global solar magnetic field generated by a flux transport model. Using indices derived from the absolute value of the solar magnetic field, we find good correlation between the observed photospheric magnetic activity and the observed F10.7 values. Comparing magnetogram data observed within 6 hours of the F10.7 measurements during the years 1993 through 2010, the Spearman correlation coefficient, rs, for an empirical model of F10.7 is found to be 0.98. In addition, we find little change in the empirical model coefficients and correlations between the first and second 9 year intervals of the 18 year period investigated. By evolving solar magnetic synoptic maps forward 1–7 days, this new method provides a realistic estimation of the Earth‐side solar magnetic field distribution used to forecast F10.7. Spearman correlation values of approximately 0.97, 0.95, and 0.93 are found for 1 day, 3 day, and 7 day forecasts, respectively. The method presented here can be expanded to forecast other space weather parameters, e.g., total solar irradiance and extreme ultraviolet flux. In addition, near‐term improvements to the F10.7 forecasting method, e.g., including far‐side magnetic data with solar magnetic flux transport, are discussed.

The periodic variation of 6.7 days for total solar radiation

AbstractAnalyzing the power spectrum of Total Solar Irradiance (TSI) for the period from 2003 February 25 to 2009 July 6, observed with the Total Irradiance Monitor (TIM) onboard SOlar Radiation and Climate Experiment (SORCE), we found that there are quite a number of periodic variations. The outstanding shortest one is the period of 6.7 days, about one fourth of the period of solar rotation. Checking the solar magnetic field for the same period of time observed with MDI onboard SOHO, we found that there is about 90 degree difference in longitude for the distribution of solar magnetic field. We therefore conclude that both the 90 degree difference in longitude for the distribution of solar magnetic field and the solar rotation are the reason resulting in the periodic variation of 6.7 days for the total solar radiation.

Strength distribution of solar magnetic fields in photospheric quiet Sun regions

Context. The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed Mn i line at 553.7 nm, allows such differentiation.

Longitudinal Distribution of Coronal Holes During 1976–2002

The longitudinal distribution of coronal holes has been analyzed for the time interval 1976–2002. Coronal holes don't seem to be randomly distributed. The cluster structure has been revealed in the time—space organization of coronal hole distribution. The complexity and lifetime of clusters depend on the solar cycle phase. The comparison of active region and coronal hole cluster structures shows that some coronal hole clusters as well as active region ones occur almost simultaneously in both hemispheres, some clusters in the north or in the south hemisphere only. Some coronal hole clusters coincide with the active region clusters and some do not coincide. They reflect the large-scale solar magnetic field distribution.

Study of bi-orthogonal modes in magnetic butterflies

Fil: Mininni, Pablo Daniel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Fisica de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisica de Buenos Aires; Argentina

The Interaction of New and Old Magnetic Fluxes at the Beginning of Solar Cycle 23

The 11-year cycle of solar activity follows Hale's law by reversing the magnetic polarity of leading and following sunspots in bipolar regions during the minima of activity. In the 1996-97 solar minimum, most solar activity emerged in narrow longitudinal zones - `active longitudes' but over a range in latitude. Investigating the distribution of solar magnetic flux, we have found that the Hale sunspot polarity reversal first occurred in these active zones. We have estimated the rotation rates of the magnetic flux in the active zones before and after the polarity reversal. Comparing these rotation rates with the internal rotation inferred by helioseismology, we suggest that both `old' and `new' magnetic fluxes were probably generated in a low-latitude zone near the base of the solar convection zone. The reversal of active region polarity observed in certain longitudes at the beginning of a new solar cycle suggests that the phenomenon of active longitudes may give fundamental information about the mechanism of the solar cycle. The non-random distribution of old-cycle and new-cycle fluxes presents a challenge for dynamo theories, most of which assume a uniform longitudinal distribution of solar magnetic fields.

On the Multifractal Distribution of Solar Magnetic Fields: Erratum

view Abstract Citations References (1) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS On the Multifractal Distribution of Solar Magnetic Fields: Erratum Lawrence, J. K. ; Cadavid, A. C. ; Ruzmaikin, A. A. Abstract Many studies have pointed out fractal and multifractal properties of photospheric magnetic fields, but placing the various approaches into context has proved difficult. Although fractal quantities are defined mathematically in the asymptotic limit of infinite resolution, real data cannot approach this limit. Instead, one must compute fractal dimensions or multifractal spectra within a limited range at finite scales. The consequent effects of this are explored by calculation of fractal quantities in finite images generated from analytically known measures and also from solar data. We find that theorems relating asymptotic quantities need not hold for their finite counterparts, that different definitions of fractal dimension that merge asymptotically give different values at finite scales, and that apparently elementary calculations of dimensions of simple fractals can lead to incorrect results. We examine the limits of accuracy of multifractal spectra from finite data and point out that a recent criticism of one approach to such problems is incorrect. Publication: The Astrophysical Journal Pub Date: August 1996 DOI: 10.1086/177622 Bibcode: 1996ApJ...467..473L Keywords: ERRATA; ADDENDA full text sources ADS | Related Materials (1) Original Paper: 1996ApJ...465..425L

Formation of Coronal Holes and the Global Magnetic Field Distribution

The photoelectric magnetograph of the Ondřejov Observatory was reconstructed in 1990 (Klvaňa and Bumba, 1994; Klvaňaet al, 1994). During 1991 and 1992, several hundred sets of measurements were obtained, mostly in line Fel 5253.47 Å. It has been found that some of the measurements are distributed very favorably around coronal holes, sometimes covering smaller parts and in a few cases even larger parts of their areas.Both 1991 and 1992 were exceptional as regards their relation to the phase of the ending solar activity cycle (No 22): while the period of the secondary cycle maximum (mainly the southern solar hemisphere) took place in 1991, the year 1992 coincided with the initial stage of its declining branch. Since the formation of coronal holes is in close relation to the dynamics of the global distribution of solar magnetic fields, we thought that before starting to investigate the detailed connections of the individual coronal holes with particular local magnetic fields, it might be interesting to study their mutual relations also on a large scale.

Does the large-scale solar magnetic field distribution really reflect the convective velocity fields?

We have tried to decide whether the typical circular cellular-like features, which are striking during some intervals in the large-scale distribution of weak magnetic fields measured with low resolution, are related to large-scale convective motions. Two scales of such patterns were found and their morphological, kinematical and evolutionary behaviour was estimated. Their slower and overall rotation is also demonstrated in comparison with the rotation of highly averaged sunspot and magnetic fields. It is difficult to explain all the observed characteristics as random, or due to the method of field measurement and map construction used. We also discuss the change of their magnetic field polarities with the solar polar field reversal.

Solar magnetic field distribution and geomagnetic activity

Regularities in the solar background magnetic field distribution are described and some of their specific patterns and their structures are studied. The influence of the solar differential rotation on the behaviour of “Magnetic Active Longitudes” is demonstrated. The origin of some specific details different in both polarities is discussed. The relation of this longitudinal solar magnetic field distribution to the longitudinal distribution of the daily geomagnetic character figures C9 is investigated. Some correlational characteristics are given. The specific “Index of Geomagnetic Recurrence” is estimated and the changes of its values in time are demonstrated.

Large-Scale Solar Magnetic Fields

The characteristics of the large-scale distribution of the solar magnetic fields on the basis of a series of solar magnetic synoptic charts covering more than 15 years of observations are given. The major part of our information concerns the morphology and only some results deal with the kinematics of the field distribution. Results of averaged solar magnetic field fluxes and polarity reversal studies as well as of preliminary investigation of the very-low angular resolution magnetic measurements are given. The regular zonal and sectoral distribution of photospheric background fields, the different role or visibility of structures in both polarities is discussed. The reflection of both main types of the longitudinal distribution of large-scale solar background magnetic fields (the 27-day, the 28–29-day successions, the ‘supergiant’ structures) in the interplanetary magnetic field distribution is also considered.

Large-Scale Distribution of Solar Magnetic Fields.

Solar magnetograms covering a period of years were used to study the distribution of weak magnetic fields on the solar surface. The semiregular pattern of these background fields is the result of the expansion, weakening, and stretching by differential rotation of magnetic fields of old active regions and their interaction with neighboring fields, and of the continuing development of magnetic fields of new regions within the pattern. The net result is a slowly changing pattern of background fields which occupies at times during the solar cycle more than 50 per cent of the surface area of the Sun, as seen with the 23" resolution of the magnetograph. The interaction of nearby magnetic fields takes the form of the apparent attraction of features of the same polarity and the apparent repulsion of features of opposite polarity. Sometimes weak magnetic features covering a large area apparently disappear over a period of a few rotations. It is not clear from the observations what the mechanism of this disappearance could be. It is clear from the period near minimum that active regions are concentrated in complexes of activity whose location and development are clearly defined. The largest of these complexes, consisting of many active regions, result in the formation of Unipolar Magnetic Regions (UMR). The polar fields are discussed from the standpoint of the poleward drift of the UMR's.