We study the solar flare index (SFI) for the Solar Cycles 18 – 24. We find that SFI has deeper Gn... more We study the solar flare index (SFI) for the Solar Cycles 18 – 24. We find that SFI has deeper Gnevyshev gap (GG) in its first principal component than other atmospheric parameters. The GG is extremely clear especially in the even cycles.The GG of the SFI appears about a half year later as a drop in the interplanetary magnetic field near the Earth and in the geomagnetic Ap-index. The instantaneous response of the magnetic field to solar flares, however, shows about two to three days after the eruption as a high, sharp peak in the cross-correlation of the SFI and Ap-index and as a lower peak in SFI vs. IMF B cross-correlation. We confirm these rapid responses using superposed-epoch analysis.The most active flare cycles during 1944 – 2020 are Cycles 19 and 21. Cycle 18 has very strong SFI days as many as Cycle 22, but it has the least nonzero SFI days in the whole interval. Interestingly, Cycle 20 can be compared to Cycles 23 and 24 in its low flare activity, although it is located be...
A detailed analysis has been made of 13 periods of 20 days of the AE data. The average correlatio... more A detailed analysis has been made of 13 periods of 20 days of the AE data. The average correlation dimension is found to be 3.4, and the calculated dimension is found to depend on the magnetospheric activity such that more active periods have smaller dimensions. This apparent correlation dimension does not, however, imply that the magnetospheric system behind the AE
We study the annual periodicity and the solar rotation periodicity of the in‐ecliptic components ... more We study the annual periodicity and the solar rotation periodicity of the in‐ecliptic components of the interplanetary magnetic field (IMF). It is well known that the annual periodicity undergoes a phase reversal in 11 years, reflecting the 22‐year Hale cycle of the solar magnetic field. We construct a model where the annual periodicity of the IMF components is phase/frequency modulated by the Hale cycle, and show that this model can reproduce the observed properties of the annual periodicity. We find that the solar rotation periodicity depicts an analogous nodal structure and a phase reversal with a period of about 3.2 years, implying a new periodicity in the properties of the IMF. We demonstrate that, using the observed spectral width, the phase/frequency modulation model can satisfactorily explain this structure. We also note that taking into account the observed phase reversal in the solar rotation periodicity implies that the most persistent synodic solar rotation period in the in‐ecliptic IMF components is 27.6 days, i.e., somewhat longer than recently suggested.
We study the latitudinal distribution and temporal evolution of the sunspot penumbra-umbra ratio ... more We study the latitudinal distribution and temporal evolution of the sunspot penumbra-umbra ratio ($q$ q ) for the even and odd Solar Cycles 12 – 24 of RGO sunspot groups, SC21 – SC24 of Debrecen sunspot groups and Kodaikanal sunspot dataset for SC16 – SC24. We find that RGO even (odd) Cycles have $q$ q -values 5.20 (4.75), Kodaikanal even (odd) cycles have $q$ q -values 5.27 (5.43), and Debrecen cycles have $q$ q -value 5.74 on the average.We also show that $q$ q is at its lowest around the Equator of the Sun and increases towards higher latitudes having maximum values at about 10 – 25 degrees. This is understandable because smaller sunspots and groups locate nearer to the Equator and have smaller $q$ q -values than larger sunspots and groups, which maximize at about 10 – 20 degrees at both hemispheres. The error limits are very wide, and, thus, the confidence in this result is somewhat vague.For the Debrecen dataset, we find a deep valley in the temporal $q$ q -values before the mi...
We decompose the monthly cosmic-ray data, using several neutron-monitor count rates, of Cycles 19... more We decompose the monthly cosmic-ray data, using several neutron-monitor count rates, of Cycles 19 – 24 with principal component analysis (PCA). Using different cycle limits, we show that the first and second PC of cosmic-ray (CR) data explain 77 – 79% and 13 – 15% of the total variation of the Oulu CR Cycles 20 – 24 (C20 – C24), 73 – 77% and 13 – 17% of the variation of Hermanus C20 – C24, and 74 – 78% and 17 – 21% of the Climax C19 – C22, respectively. The PC1 time series of the CR Cycles 19 – 24 has only one peak in its power spectrum at the period 10.95 years, which is the average solar-cycle period for SC19 – SC24. The PC2 time series of the same cycles has a clear peak at period 21.90 (Hale cycle) and another peak at one third of that period with no peak at the solar-cycle period. We show that the PC2 of the CR is essential in explaining the differences in the intensities of the even and odd cycles of the CR. The odd cycles have a positive phase in the first half and a negative...
The homogeneous coronal data set (HCDS) of the green corona (Fe xiv) and the coronal index of sol... more The homogeneous coronal data set (HCDS) of the green corona (Fe xiv) and the coronal index of solar activity (CI) have been used to study the time–latitudinal distribution in Solar Cycles 18 – 24 and compared with similar distribution of sunspots, the magnetic fields, and the solar 10.7 cm radio flux. The most important results are: i) the distribution of coronal intensities related to the cycle maximum are different for individual cycles, ii) the poleward migration of the HCDS from mid-latitudes in each cycle exists, even in the extremely weak Cycle 24, and the same is valid for the equatorward migration, iii) the overall values of HCDS are slightly stronger for the northern hemisphere than for the southern one, iv) the distribution of the HDCS is in coincidence with the strongest photospheric magnetic fields ($B>$ B > 50 Gauss) and histograms of the sunspot groups, v) the Gnevyshev gap was confirmed with at least 95% confidence in the CI, however with different behavior for ...
Optics and Photonics for Counterterrorism, Crime Fighting, and Defence X; and Optical Materials and Biomaterials in Security and Defence Systems Technology XI, 2014
A novel method is presented for distinguishing postal stamp forgeries and counterfeit banknotes f... more A novel method is presented for distinguishing postal stamp forgeries and counterfeit banknotes from genuine samples. The method is based on analyzing differences in paper fibre networks. The main tool is a curvelet-based algorithm for measuring overall fibre orientation distribution and quantifying anisotropy. Using a couple of more appropriate parameters makes it possible to distinguish forgeries from genuine originals as concentrated point clouds in two- or three-dimensional parameter space.
We study distributions of differences of unscaled Riemann zeta zeros, γ-γ^', at large. We sho... more We study distributions of differences of unscaled Riemann zeta zeros, γ-γ^', at large. We show, that independently of the location of the zeros, i.e., even for zeros as high as 10^23, their differences have similar statistical properties. The distributions of differences are skewed usually towards the nearest zeta zero. We show, however, that this is not always the case, but depends upon the distance and number of nearby zeros on each side of the corresponding distribution. The skewness, however, always decreases when zeta zero is crossed from left to right, i.e., in increasing direction. Furthermore, we show that the variance of distributions has local maximum or, at least, a turning point at every zeta zero, i.e., local minimum of the second derivative of the variance. In addition, it seems that the higher the zeros the more compactly the distributions of the differences are located in the skewness-kurtosis -plane. Furthermore, we show that distributions can be fitted with Joh...
We study distributions of differences of unscaled Riemann zeta zeros, γ-γ', at large. We show... more We study distributions of differences of unscaled Riemann zeta zeros, γ-γ', at large. We show, that independently of the location of the zeros, their differences have similar statistical properties. The distributions of differences are skewed towards the nearest zeta zero, have local maximum of variance and local minimum of kurtosis at or near each zeta zero. Furthermore, we show that distributions can be fitted with Johnson probability density function, despite the value of skewness or kurtosis of the distribution.
We study the evolution of continental, zonal and seasonal land temperature anomalies especially i... more We study the evolution of continental, zonal and seasonal land temperature anomalies especially in the early 20th century warming (ETCW) period, using principal component analysis (PCA) and reverse arrangement trend analysis. ETCW is significant in all other continents except for Oceania. Warming in South America is significant from the ETCW onwards, but significant recent warming started in North America and Europe only around 1990. The zonal and seasonal PC2s are both correlated with AMO index, but zonal PC3 is related to Southern oscillation index (SOI) and seasonal PC3 best correlated with wintertime El Nino (NINO34 DJF index). In the southern hemisphere, the recent warming starts first closest to the equator in the 1950s and latest in the southernmost zone in the late 1970s. In the two lowest northern zones (EQ-N24, N24-N44) the warming is significant since the ETCW, and increased warming starts in 1970s, but in two northernmost zones (N44-N64, N64-N90) the cooling after the ET...
We study the solar flare index (SFI) for the Solar Cycles 18 – 24. We find that SFI has deeper Gn... more We study the solar flare index (SFI) for the Solar Cycles 18 – 24. We find that SFI has deeper Gnevyshev gap (GG) in its first principal component than other atmospheric parameters. The GG is extremely clear especially in the even cycles.The GG of the SFI appears about a half year later as a drop in the interplanetary magnetic field near the Earth and in the geomagnetic Ap-index. The instantaneous response of the magnetic field to solar flares, however, shows about two to three days after the eruption as a high, sharp peak in the cross-correlation of the SFI and Ap-index and as a lower peak in SFI vs. IMF B cross-correlation. We confirm these rapid responses using superposed-epoch analysis.The most active flare cycles during 1944 – 2020 are Cycles 19 and 21. Cycle 18 has very strong SFI days as many as Cycle 22, but it has the least nonzero SFI days in the whole interval. Interestingly, Cycle 20 can be compared to Cycles 23 and 24 in its low flare activity, although it is located be...
A detailed analysis has been made of 13 periods of 20 days of the AE data. The average correlatio... more A detailed analysis has been made of 13 periods of 20 days of the AE data. The average correlation dimension is found to be 3.4, and the calculated dimension is found to depend on the magnetospheric activity such that more active periods have smaller dimensions. This apparent correlation dimension does not, however, imply that the magnetospheric system behind the AE
We study the annual periodicity and the solar rotation periodicity of the in‐ecliptic components ... more We study the annual periodicity and the solar rotation periodicity of the in‐ecliptic components of the interplanetary magnetic field (IMF). It is well known that the annual periodicity undergoes a phase reversal in 11 years, reflecting the 22‐year Hale cycle of the solar magnetic field. We construct a model where the annual periodicity of the IMF components is phase/frequency modulated by the Hale cycle, and show that this model can reproduce the observed properties of the annual periodicity. We find that the solar rotation periodicity depicts an analogous nodal structure and a phase reversal with a period of about 3.2 years, implying a new periodicity in the properties of the IMF. We demonstrate that, using the observed spectral width, the phase/frequency modulation model can satisfactorily explain this structure. We also note that taking into account the observed phase reversal in the solar rotation periodicity implies that the most persistent synodic solar rotation period in the in‐ecliptic IMF components is 27.6 days, i.e., somewhat longer than recently suggested.
We study the latitudinal distribution and temporal evolution of the sunspot penumbra-umbra ratio ... more We study the latitudinal distribution and temporal evolution of the sunspot penumbra-umbra ratio ($q$ q ) for the even and odd Solar Cycles 12 – 24 of RGO sunspot groups, SC21 – SC24 of Debrecen sunspot groups and Kodaikanal sunspot dataset for SC16 – SC24. We find that RGO even (odd) Cycles have $q$ q -values 5.20 (4.75), Kodaikanal even (odd) cycles have $q$ q -values 5.27 (5.43), and Debrecen cycles have $q$ q -value 5.74 on the average.We also show that $q$ q is at its lowest around the Equator of the Sun and increases towards higher latitudes having maximum values at about 10 – 25 degrees. This is understandable because smaller sunspots and groups locate nearer to the Equator and have smaller $q$ q -values than larger sunspots and groups, which maximize at about 10 – 20 degrees at both hemispheres. The error limits are very wide, and, thus, the confidence in this result is somewhat vague.For the Debrecen dataset, we find a deep valley in the temporal $q$ q -values before the mi...
We decompose the monthly cosmic-ray data, using several neutron-monitor count rates, of Cycles 19... more We decompose the monthly cosmic-ray data, using several neutron-monitor count rates, of Cycles 19 – 24 with principal component analysis (PCA). Using different cycle limits, we show that the first and second PC of cosmic-ray (CR) data explain 77 – 79% and 13 – 15% of the total variation of the Oulu CR Cycles 20 – 24 (C20 – C24), 73 – 77% and 13 – 17% of the variation of Hermanus C20 – C24, and 74 – 78% and 17 – 21% of the Climax C19 – C22, respectively. The PC1 time series of the CR Cycles 19 – 24 has only one peak in its power spectrum at the period 10.95 years, which is the average solar-cycle period for SC19 – SC24. The PC2 time series of the same cycles has a clear peak at period 21.90 (Hale cycle) and another peak at one third of that period with no peak at the solar-cycle period. We show that the PC2 of the CR is essential in explaining the differences in the intensities of the even and odd cycles of the CR. The odd cycles have a positive phase in the first half and a negative...
The homogeneous coronal data set (HCDS) of the green corona (Fe xiv) and the coronal index of sol... more The homogeneous coronal data set (HCDS) of the green corona (Fe xiv) and the coronal index of solar activity (CI) have been used to study the time–latitudinal distribution in Solar Cycles 18 – 24 and compared with similar distribution of sunspots, the magnetic fields, and the solar 10.7 cm radio flux. The most important results are: i) the distribution of coronal intensities related to the cycle maximum are different for individual cycles, ii) the poleward migration of the HCDS from mid-latitudes in each cycle exists, even in the extremely weak Cycle 24, and the same is valid for the equatorward migration, iii) the overall values of HCDS are slightly stronger for the northern hemisphere than for the southern one, iv) the distribution of the HDCS is in coincidence with the strongest photospheric magnetic fields ($B>$ B > 50 Gauss) and histograms of the sunspot groups, v) the Gnevyshev gap was confirmed with at least 95% confidence in the CI, however with different behavior for ...
Optics and Photonics for Counterterrorism, Crime Fighting, and Defence X; and Optical Materials and Biomaterials in Security and Defence Systems Technology XI, 2014
A novel method is presented for distinguishing postal stamp forgeries and counterfeit banknotes f... more A novel method is presented for distinguishing postal stamp forgeries and counterfeit banknotes from genuine samples. The method is based on analyzing differences in paper fibre networks. The main tool is a curvelet-based algorithm for measuring overall fibre orientation distribution and quantifying anisotropy. Using a couple of more appropriate parameters makes it possible to distinguish forgeries from genuine originals as concentrated point clouds in two- or three-dimensional parameter space.
We study distributions of differences of unscaled Riemann zeta zeros, γ-γ^', at large. We sho... more We study distributions of differences of unscaled Riemann zeta zeros, γ-γ^', at large. We show, that independently of the location of the zeros, i.e., even for zeros as high as 10^23, their differences have similar statistical properties. The distributions of differences are skewed usually towards the nearest zeta zero. We show, however, that this is not always the case, but depends upon the distance and number of nearby zeros on each side of the corresponding distribution. The skewness, however, always decreases when zeta zero is crossed from left to right, i.e., in increasing direction. Furthermore, we show that the variance of distributions has local maximum or, at least, a turning point at every zeta zero, i.e., local minimum of the second derivative of the variance. In addition, it seems that the higher the zeros the more compactly the distributions of the differences are located in the skewness-kurtosis -plane. Furthermore, we show that distributions can be fitted with Joh...
We study distributions of differences of unscaled Riemann zeta zeros, γ-γ', at large. We show... more We study distributions of differences of unscaled Riemann zeta zeros, γ-γ', at large. We show, that independently of the location of the zeros, their differences have similar statistical properties. The distributions of differences are skewed towards the nearest zeta zero, have local maximum of variance and local minimum of kurtosis at or near each zeta zero. Furthermore, we show that distributions can be fitted with Johnson probability density function, despite the value of skewness or kurtosis of the distribution.
We study the evolution of continental, zonal and seasonal land temperature anomalies especially i... more We study the evolution of continental, zonal and seasonal land temperature anomalies especially in the early 20th century warming (ETCW) period, using principal component analysis (PCA) and reverse arrangement trend analysis. ETCW is significant in all other continents except for Oceania. Warming in South America is significant from the ETCW onwards, but significant recent warming started in North America and Europe only around 1990. The zonal and seasonal PC2s are both correlated with AMO index, but zonal PC3 is related to Southern oscillation index (SOI) and seasonal PC3 best correlated with wintertime El Nino (NINO34 DJF index). In the southern hemisphere, the recent warming starts first closest to the equator in the 1950s and latest in the southernmost zone in the late 1970s. In the two lowest northern zones (EQ-N24, N24-N44) the warming is significant since the ETCW, and increased warming starts in 1970s, but in two northernmost zones (N44-N64, N64-N90) the cooling after the ET...
Uploads
Papers