Untitled

Макаров, В. И.; Tlatov, A. G.; Sivaraman, K. R.

doi:10.1023/a:1011855103278

Cited by 52 publications

(47 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the input of the BMRs emergences is randomly distributed on the two hemispheres, our reconstructed north and south polar fields are similar. The reversal times (indicated by cyan vertical lines) are similar to those given by Makarov et al (2003). The largest differences between the models occur in cycle 19.…”

Section: Comparison Of the Model For The Time Period From 1913 To 1986supporting

confidence: 63%

“…The time evolution of the open flux derived from geomagnetic indices (Lockwood 2003;Lockwood et al 2009), and the reversal times of polar fields A83, page 2 of 11 ( Makarov et al 2003) were well reproduced. We therefore begin by comparing the results obtained using the current model based on sunspot numbers with those in CJSS10.…”

Section: Comparison Of the Model For The Time Period From 1913 To 1986mentioning

confidence: 74%

See 1 more Smart Citation

The solar magnetic field since 1700

Jiang

Cameron

Schmitt

et al. 2011

A&A

View full text Add to dashboard Cite

We have used semi-synthetic records of emerging sunspot groups based on sunspot number data as input for a surface flux transport model to reconstruct the evolution of the large-scale solar magnetic field and the open heliospheric flux from the year 1700 onward. The statistical properties of the semi-synthetic sunspot group records reflect those of the observed Royal Greenwich Observatory photoheliographic results. These include correlations between the sunspot numbers and sunspot group latitudes, longitudes, areas and tilt angles. The reconstruction results for the total surface flux, the polar field, and the heliospheric open flux (determined by a current sheet source surface extrapolation) agree well with the available observational or empirically derived data and reconstructions. We confirm a significant positive correlation between the polar field during activity minimum periods and the strength of the subsequent sunspot cycle, which has implications for flux transport dynamo models for the solar cycle. Just prior to the Dalton minimum, at the end of the 18th century, a long cycle was followed by a weak cycle. We find that introducing a possibly "lost" cycle between 1793 and 1800 leads to a shift of the minimum of the open flux by 15 years which is inconsistent with the cosmogenic isotope record.

show abstract

Section: Comparison Of the Model For The Time Period From 1913 To 1986supporting

confidence: 63%

Section: Comparison Of the Model For The Time Period From 1913 To 1986mentioning

confidence: 74%

The solar magnetic field since 1700

Jiang

Cameron

Schmitt

et al. 2011

A&A

View full text Add to dashboard Cite

show abstract

“…We remark that, when computing p over the whole time period and in the above frequency ranges, we obtain the same results computed through Equation (5) listed in the first and third column of Table 2. The parameter p has been computed in selected time intervals where there is no well defined HMF polarity, as has been reported in the literature (Makarov & Sivaraman 1986;Bazilevskaya et al 2000;Gopalswamy et al 2003). Values are listed in Table 3, which also indicates the sign (plus or minus) of the mean drift-associated mode in the considered time interval.…”

Section: Estimation Of Drift Effectsmentioning

confidence: 99%

Drift Effects on the Galactic Cosmic Ray Modulation

Laurenza

Vecchio

Storini

et al. 2014

ApJ

View full text Add to dashboard Cite

Cosmic ray (CR) modulation is driven by both solar activity and drift effects in the heliosphere, although their role is only qualitatively understood as it is difficult to connect the CR variations to their sources. In order to address this problem, the Empirical Mode Decomposition technique has been applied to the CR intensity, recorded by three neutron monitors at different rigidities (Climax, Rome, and Huancayo-Haleakala (HH)), the sunspot area, as a proxy for solar activity, the heliospheric magnetic field magnitude, directly related to CR propagation, and the tilt angle (TA) of the heliospheric current sheet (HCS), which characterizes drift effects on CRs. A prominent periodicity at ∼six years is detected in all the analyzed CR data sets and it is found to be highly correlated with changes in the HCS inclination at the same timescale. In addition, this variation is found to be responsible for the main features of the CR modulation during periods of low solar activity, such as the flat (peaked) maximum in even (odd) solar cycles. The contribution of the drift effects to the global Galactic CR modulation has been estimated to be between 30% and 35%, depending on the CR particle energy. Nevertheless, the importance of the drift contribution is generally reduced in periods nearing the sunspot maximum. Finally, threshold values of ∼40 • , ∼45 • , and >55 • have been derived for the TA, critical for the CR modulation at the Climax, Rome, and HH rigidity thresholds, respectively.

show abstract

“…They demonstrated the excellent agreement between the polar reversals obtained from the filament bands and those from the magnetograms. Following this, they worked out the epochs of polar field reversals over a period of 12 solar cycles (1872-2001) (Figure 1 of Makarov & Sivaraman (1989)) and (Figure 1 of Makarov et al (2001a)). …”

mentioning

confidence: 99%

Secular and cycle variations of polar activity of the Sun

Макаров¹,

Tlatov²,

Callebaut³

2004

Proc. IAU

Self Cite

View full text Add to dashboard Cite

Abstract. An analysis of polar activity of the Sun was carried out using the observations in the optical range. The secular and cycle peculiarities of the magnetic activity on the high latitudes were found: 1. an increase of the area of polar caps of the Sun, occupied by unipolar magnetic field at the minimum activity during 1878-2000; 2. a decrease of coronal temperature at the high-latitude zones during the last 50 years; 3. the connection between the polar and sunspot activities; 4. outset and duration of the polar activity cycle; 5. drift of the activity to the poles and from the poles after the magnetic field reversal.In the absence of a long-term record of magnetograph measurements of the solar magnetic field the investigation of polar activity of the Sun in the last 120 years has been based on the latitude-time distribution of unipolar areas of the large-scale magnetic field during 1878-2000. The unipolar regions are evident on magnetograms. At the boundaries of unipolar regions where the radial component of the magnetic field is zero, H α prominences and dark filaments are observed. They form the pattern of the so-called magnetic neutral lines, Fig. 1.I. We calculated the area of polar zones of the Sun, A pz , occupied by unipolar magnetic field on H α synoptic magnetic charts from 1878 to 1996. We found a gradual decrease of the annual minimum latitude of the high-latitude zone boundaries, Θ 2m , of the global magnetic field of the Sun at the minimum of activity from 53• in 1878 down to 38 • in 1996, Fig. 2., yielding an average decrease of 1.2• per cycle, (Makarov et al. (2002)). We compared < A pz > 11 with the < aa > 11 and the Wolf number < W > 11 , Fig. 3.:Here we use the correlation between the geomagnetic < aa > 11 index and polar cap areas < A pz > 11 to obtain an estimate of the latitude of the high-latitude zone boundary Θ 2m in the Maunder Minimum. Using "11-year" average of index we obtained: < aa > 11 ≈ 1.2 < A pz > 11 −3.0; sinΘ 2m ≈ −0.014 < aa > 11 +0.96. Using these estimates one can find that the polar cap areas of the Sun < A pz > 11 correspond to the value of Θ 2m ≈ 60• in Maunder Minimum, Fig. 4. It is known that Earth's surface temperature is correlated with the geomagnetic < aa > 11 index. For the period 1880-2000 we found: < T > 11 ≈ 0.039 < aa > 11 −0.88; < T > 11 ≈ 1.8• − 2.9• sinΘ 2m We can extrapolate to the Maunder Minimum to infer the solar induced temperature 49 https://www.cambridge.org/core/terms. https://doi

show abstract

Untitled

Cited by 52 publications

References 26 publications

The solar magnetic field since 1700

The solar magnetic field since 1700

Drift Effects on the Galactic Cosmic Ray Modulation

Secular and cycle variations of polar activity of the Sun

Contact Info

Product

Resources

About