Active longitudes of sunspots

The inhomogeneity of the sunspot group longitude distribution has been determined depending on the rotation period used to determine a longitude. The statistical significance of the found active longitudes has been estimated. It has been indicated that a rather high reliability is reached only when the synodic rotation period is close to 27 and 28 days. In this case active longitudes show the long-term variation related to the north-south asymmetry of the sunspot formation. It is assumed that active longitudes are related to the relic magnetic field frozen in a uniformly rotating solar radiative zone.     

Difference between the even and odd 11-year cycles of geomagnetic activity

Summary With the aid of 36 monthly and a double 12-month running average, graphs of the smoothed run of geomagnetic activity were constructed from the monthly values of the geomagnetic activity index aa for the period 1868–1978 and they were then used to determine the run of the geomagnetic activity, expressed during a uniform period and devoid of the secular variation of geomagnetic activity, for the individual 11-year cycles Nos 12–20 and the average runs for even and odd cycles, as well as for the whole period of the 9 cycles. The analysis and comparison of the graphs substantiates and renders more accurate the tendency, observed earlier, towards a regular alternation of geomagnetic activity cycles with double and single maxima. Wheareas a saddle-like shape with a maximum in the neighbourhood of the first and third quarter of the cycle is characteristic of the shape of the even cycle, the second maximum being, as a rule, the main one, the odd cycle is characterized by a peak-like shape with the main maximum in the vicinity of the cycle's centre.     

Hysteresis of indices of solar and ionospheric activity during 11-year cycles

The effects of hysteresis, which is a manifestation of ambiguous relationships between different solar activity indices during the rising and declining phases of solar cycles, are analyzed. The paper addresses the indices characterizing radiation from the solar photosphere, chromosphere, and corona, and the ionospheric indices. The 21st, 22nd, and 23rd solar cycles, which significantly differ from each other in amplitude, exhibit different extents of hysteresis.     

The connection between characteristic values of the 11-year cycles of solar and of geomagnetic activity

Summary Using the annual values of the indices of solar and geomagnetic activity for the period 1868–1976, the basic values characterizing the cycle as a whole were determined for the 11-year cycles nos 11–20, (Tab. 1). High values of the coefficients of correlation were found for some pairs of characteristic values of the same and different kinds, given in Tab. 2, which can be utilized for long-term predictions of geomagnetic activity.

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a auu¶rt;u au u¶rt; uaum amumu muu 1868–1976 n¶rt; ¶rt; 11-mu u 11–20 naam aamuu u a (a. 1). u au uuma uu ¶rt; m na naam ¶rt;ua u ¶rt;ua ¶rt;a (a. 2), m m amu nuu nu ¶rt; nuauuaum amumu.

     

On the connections between the 11-year sunspot period and the periods of about 3 and 7 years in world weather

Summary Five ofBerlage's eight empirical rules concerning the Southern Oscillation (1957) may be united in one general rule with regard to the different influence of solar activity during 11-year sunspot cycles with annual maximum numberR above or below 85 (Tables 2, 3, 4, 5 and 6). The opposite character of strong and weak 11-year cycles of solar activity is also present in the 7-year period (Tables 7, 8, 9 and 10; Fig. 1). Finally it is shown that a similar contrast obviously exists in the appearance of polar lights (Table 11, Fig. 2 and 3).The results have not been statistically tested. Because of the rather small number of solar periods involved and the complicated character of the relations found, I could not find a satisfactory statistical method to operate with. I may emphasize, however, the converging evidence enlarging considerably the statistical significance of my results.     

Wavelet image of the fine structure of the 11-year cycle based on studying cosmic ray fluctuations during cycles 20–23

A non-stationary transient oscillating process of the solar magnetic field polarity reversal of ≈3 years in duration has been established: a U-shaped dynamics in the wavelet representation of variations in the scintillation index of galactic cosmic rays (GCRs) (≈7, 13–14, and ≈7 solar rotations). The transient oscillating process of the field reversal is concluded with a sharp and deep decrease in the GCR intensity at the branch of 11-year cycle decline (1972, 1982, 1991, and 2003). The duration of the transient process inversely depends on the 11-year cycle amplitude. Retardation of relaxation oscillations during “weak” cycles (20 and 23) explains “anomalous” solar activity in 1972 and 2003. A decrease in the amplitude of the current cycle 23 is accompanied by an increase in its duration, which can mean that the 11-year cyclicity has become anomalous. The constancy of the energy released in a single cycle indicates that the 11-year cycle is the mechanism of energy regulation preventing the Sun from “overheating” at the critical temperature.     

Characteristics of the tropical tropopause over different longitudes

The characteristics of the cold point tropopause (CPT), convective tropopause (COT) and tropical tropopause layer (TTL) in the tropical region at different longitudes are studied using radiosonde data at 5 stations in the tropical belt (±15°) and high resolution GPS radiosonde data from April 2006 to December 2008 at Gadanki (13.5°N, 79.2°E) also a tropical station. The CPT over Gadanki is found to be higher than over the rest of the stations. This aspect is further confirmed using COSMIC GPS RO observations. In the Northern Hemisphere (NH) winter, the CPT is coldest over stations in the Pacific region compared to the other stations while in the NH summer, it is coldest at Gadanki, a station in the Indian monsoon region. The range of seasonal variation of the CPT temperature is found to be quite small over Gadanki compared to the other stations whereas that of the CPT altitude is nearly the same.     

The signal of the 11-year solar cycle in the global stratosphere

The search for a signal of the 11-year sunspot cycle in the heights and temperatures of the lower stratosphere was previously successfully conducted for the northern hemisphere with a data set from the Freie Universität Berlin, covering four solar cycles. This work has been extended to the whole globe by means of the NCEP/NCAR reanalyses for the period 1968–1996. The re-analyses show that the signal exists in the southern hemisphere too, and that it is of nearly the same size and shape as on the northern hemisphere. The NCEP/NCAR reanalyses yield higher correlations with the solar cycle than do the Berlin analyses for the same period, because the interannual variability is lower in the NCEP/NCAR data.The correlations between the solar cycle and the zonally averaged temperatures at the standard levels between 200 and 10 hPa are largest between the tropopause and the 25 km level, that is, in the ozone layer. This may be partly a direct effect in this layer, because of more absorber (ozone) and more ultraviolet radiation from the sun in the peaks of the 11-year solar cycle. However, it is more likely to be mainly an indirect dynamical consequence of UV absorption by ozone in the middle and upper stratosphere.The largest temperature correlations move with the sun from one summer hemisphere to the other, and the largest height correlations move poleward from winter to summer.     

太阳活动11年周期对气象参数影响

利用多种资料研究了太阳活动11年周期对全球气温、风场、海表温度(SST)的影响,结果表明:(1)在第21、22太阳活动周,中低纬对流层顶以上大气温度变化具有类似太阳黑子变化的11年左右周期,相对于太阳黑子数,气温变化具有1～2年的延迟性;相对于太阳活动低年,200～10 hPa大气在太阳活动高年整层增温,以赤道低纬地区...     

Special points in 11-year variations in the latitudinal characteristics of sunspot activity

It has been indicated that special moments (turning points), when certain characteristics of the latitudinal (equatorward) drift of the sunspot drift zone suddenly change, exist in each 11-year solar cycle. The moment when a sunspot formation low-latitude boundary minimum (T2), coordinated in time with the end of a polar magnetic field polarity reversal, exists has a special place among these points. A conclusion has been drawn that it is impossible to reconstruct polarity reversal moments in the past based on information about turning points T2. The average velocities of the latitudinal drift of the minimal, average, and maximal sunspot group latitudes have been calculated. It has been indicated that the closeness of the relationship between the first two velocities and the maximal activity amplitudes in the cycles differ substantially for the first (before point T2) and second (after point T2) cycle parts. The corresponding values of the correlation coefficients increase substantially in the second cycle (after point T2). It has been established that a relationship exists between some velocities calculated in these cycles and the activity amplitudes at maximums of the next cycles. A model for predicting future cycle maximums has been constructed based on this conclusion. The probable average annual Wolf number at a maximum of cycle 24 has been determined (W(24) = 93).     

Effect of active longitudes in cosmic ray flux modulation

Galactic cosmic rays, registered by ground-based neutron monitors, are strongly affected by the heliosphere, i.e., being subjected to solar modulation. Cosmic ray variations are closely related to different solar activity indices and IMF parameters. The longitudinal inhomogeneity of the general solar magnetic field as a star and the manifestation of this inhomogeneity in the magnetic field are considered in the work. It has been established that the longitudinal inhomogeneity of this field, with the dipole distribution of polarities along heliolongitude, mainly contributes to 27-day modulation of galactic cosmic rays.     

Certain regularities of solar activity variations during the 11-year cycle

The relationships between a number of the main characteristic parameters of the cycle—amplitude, half-width, and growth phase duration—and the approximation parameters, which make it possible to estimate the average behavior of 11-year activity, have been derived based on the obtained analytical representations of the regularities in the solar activity variations during the cycle. Quasibiennial variations proceeding against a background of the cycle are distinctly associated with the solar magnetic field structure and the structure representation variations in the corona and in the flux of the solar neutrino radiation. This makes it possible to state that all these processes are parts of the common physical mechanism of solar variability.     

The effect of the 11-year solar cycle on the temperature in the lower stratosphere

Two temperature datasets are analyzed for quantifying the 11-year solar cycle effect in the lower stratosphere. The analysis is based on a regression linear model that takes into account volcanic, Arctic Oscillation (AO), Quasi-Biennial Oscillation (QBO) and El Nino Southern Oscillation (ENSO) effects. Under solar maximum conditions, temperatures are generally warmer for low- and mid-latitudes than under solar minimum, with the effect being the strongest in northern summer. At high latitudes, the vortex is generally stronger under solar maximum conditions, with the exception of February and to a lesser extent March in the Northern Hemisphere; associated with this positive signal at high latitudes, there is a significant negative signal at the equator. Observations also suggest that contrary to the beginning of the winter, in February–March, the residual circulation in the Northern Hemisphere is enhanced. A better understanding of the mechanisms at work comes from further investigations using the ERA-40 reanalysis dataset. First, a consistent response in terms of temperature and wind is obtained. Moreover, considering Eliassen-Palm (EP) flux divergence and residual circulation stream functions, we found an increased circulation in the Northern Hemisphere in February during solar maxima, which results in more adiabatic warming at high latitudes and more adiabatic cooling at low latitudes, thus demonstrating the dynamical origin of the response of the low stratosphere to the solar cycle.     

Anomalies of Shape of 11-year Solar Cycle in Sunspot Number Series

Geomagnetism and Aeronomy - The shape of the 11-year cycle of solar activity can be described by a set of parameters that include its amplitude, the lengths of the ascending and descending branches...