An alternative measure of solar activity from detailed sunspot datasets

The sunspot number is analyzed by using detailed sunspot data, including aspects of observability, sunspot sizes, and proper identification of sunspot groups as discrete entities of the solar activity. The tests show that besides the subjective factors there are also objective causes of the ambiguities in the series of sunspot numbers. To introduce an alternative activity measure the physical meaning of the sunspot number has to be reconsidered. It contains two components whose numbers are governed by different physical mechanisms, this is one source of the ambiguity. This article suggests an activity index, which is the amount of emerged magnetic flux. The only long-term proxy measure is the detailed sunspot area dataset with proper calibration to the magnetic flux amount. The Debrecen sunspot databases provide an appropriate source for the establishment of the suggested activity index.Comment: 11 pages, 8 figure

Variations of Solar Non-axisymmetric Activity

The temporal behaviour of solar active longitudes has been examined by using two sunspot catalogues, the Greenwich Photoheliographic Results (GPR) and the Debrecen Photoheliographic Data (DPD). The time-longitude diagrams of the activity distribution reveal the preferred longitudinal zones and their migration with respect to the Carrington frame. The migration paths outline a set of patterns in which the activity zone has alternating prograde/retrograde angular velocities with respect to the Carrington rotation rate. The time profiles of these variations can be described by a set of successive parabolae. Two similar migration paths have been selected from these datasets, one northern path during cycles 21 - 22 and one southern path during cycles 13 - 14, for closer examination and comparison of their dynamical behaviours. The rates of sunspot emergence exhibited in both migration paths similar periodicities, close to 1.3 years. This behaviour may imply that the active longitude is connected to the bottom of convection zone

Comparison of Debrecen and Mount Wilson/Kodaikanal sunspot group tilt angles and the Joy's law

The study of active region tilt angles and their variations in different time-scales plays an important role in revealing the subsurface dynamics of magnetic flux ropes and in understanding the dynamo mechanism. In order to reveal the exact characteristics of tilt angles, precise long-term tilt angle data bases are needed. However, there are only a few different data sets at present, which are difficult to be compared and cross-calibrate because of their substantial deviations. In this paper, we describe new tilt angle data bases derived from the Debrecen Photoheliographic Data (DPD) (1974–) and from the SOHO/MDI-Debrecen Data (SDD) (1996–2010) sunspot catalogues. We compare them with the traditional sunspot group tilt angle data bases of Mount Wilson Observatory (1917–85) and Kodaikanal Solar Observatory (1906–87) and we analyse the deviations. Various methods and filters are investigated which may improve the sample of data and may help in deriving better results based on combined data. As a demonstration of the enhanced quality of the improved data set a refined diagram of Joy's law is presented

Geoeffektív szoláris és interplanetáris jelenségek vizsgálata = Study of geoeffective solar and interplanetary phenomena

Fő célunk az volt, hogy előrelépés történjen a Debrecen Photoheliographic Data (DPD) napfolt-adatbázis készítésében, mely többek között a szoláris irradianciaváltozások modellezéséhez szükséges. A beszámolási időszak alatt 6 év anyaga készült el és mára az 1986-1990 és 1993-98 közötti időszak adatai már használhatók kutatásra, a jelenleg mérés alatt lévőkkel együtt pedig az 1982-2003 évekre terjed ki a munka. Több cikkünk foglalkozik a DPD módszertani fejlesztésével és prezentációjával. Az irradianciamodellezés megbízhazóságának növeléséhez nélkülözhetetlen összehasonlító vizsgálatokat végeztünk a különböző napfolt-adatbázisokkal. Az irradianciát egy további munkánk érinti, a MnI 539,47nm vonal viselkedését írtuk le, mely ígéretes irradiancia-indikátor. Ezenfelül vizsgáltunk a DPD alapján a foltterületek kelet-nyugati aszimmetriáját, és a folteloszlások kapcsolatát a torziós hullámmal. Célkitűzéseink második csoportját a plazmaáramok révén közvetített Nap-Föld hatások vizsgálata jelentette. Megmutattuk, hogyan függ a plazmák mágneses komponenseinek és sebességének féléves viselkedése a szoláris mágneses dipóltér polaritásától, valamint leírtunk egy észak-déli illetve egy kelet-nyugati aszimmetriát a szoláris plazmák és a magnetoszféra kölcsönhatásaiban. Megadtunk egy lehetséges sémát a szoláris és alsólégköri jelenségek között végbemenő hatásmechanizmusra. Harmadik célunk a napkitörések időbeli viselkedésének vizsgálata volt, leírtuk egy fler kváziperiodikus fluktuációját. | The main task was an advancement in the edition of the Debrecen Photoheliographic Data (DPD) which is a sunspot database necessary, among others, for irradiance variation models. The materials of 6 years have been completed during the project, now the data of the 1986-1990 and 1993-1998 are available for investigations and the work extends to the years 1982-2003 with the periods under measurements. Several papers are devoted to the methodology of DPD and its presentation. We compared different sunspot databases which is needed to the improvement of the irradiance models. The irradiance is referred to in another work: the behaviour of the MnI 539,47nm line (a promising irradiance indicator) was described. In addition two other phenomena have been studied on the basis of the DPD: the East-West asymmetry of spot areas and the connection of spot distributions with the torsional wave. The next group of our aims was the study of Sun-Earth impacts transferred by plasma streams. We analysed the dependence of the semiannual behaviour of plasma velocity and magnetic components on the polarity of the solar magnetic dipole field, furthermore we described asymmetries of North-South as well as of East-West type in the interaction of the solar plasmas and the magnetosphere. We provided a possible scheme for the chain of impacts between the solar and troposhperic phenomena. The third aim was the temporal analysis of flare events. We described the quasiperiodic fluctuation of a flare

Comparative analysis of Debrecen sunspot catalogues

Sunspot area data are important for studying solar activity and its long term variations. At the Debrecen Heliophysical Observatory, we compiled three sunspot catalogues: the Debrecen Photoheliographic Data (DPD), the SDO/HMI Debrecen Data (HMIDD), and the SOHO/MDI Debrecen Data. For comparison, we also compiled an additional sunspot catalogue, the Greenwich Photoheliographic Data, from the digitized Royal Greenwich Observatory images for the 1974-76. By comparing these catalogues when they overlap in time, we can investigate how various factors influence the measured area of the sunspots, and, in addition, we can derive area cross-calibration factors for these catalogues.The main findings are as follows. The poorer seeing increases the individual corrected spot areas and decreases the number of the small spots. Interestingly, the net result of these two effects for the total corrected spot area is zero. DPD daily total corrected sunspot areas are 5 per cent smaller than the HMIDD ones. Revised DPD daily total corrected umbra areas are 9 per cent smaller than those of HMIDD. The Greenwich Photoheliographic Result areas are only a few per cent smaller than DPD areas. A $0.2^{\circ}$ difference between the North directions of the DPD and MDI images is found. This value is nearly the same as that was found ($0.22^{\circ}$) by us in a previous paper comparing HMI and MDI images. The Solar Observing Optical Network area measurement practice (spots smaller than $10 mh$ were not directly measured but an area of $2 mh$ were assigned to each) can not explain the large area deficit of the Solar Observing Optical Network

Different Contributions to Space Weather and Space Climate from Different Big Solar Active Regions

The purpose of this paper is to show that large active regions (ARs) with different magnetic configurations have different contributions to short-term and long-term variations of the Sun. As a case study, the complex δ-type AR 12673 and the simple β-type AR 12674 are investigated in detail. Since the axial dipole moment at cycle minimum determines the amplitude of the subsequent cycle and space climate, we have assimilated the individual observed magnetic configurations of these two ARs into a surface flux transport model to compare their contributions to the axial dipole moment D. We find that AR 12673 has a significant effect on D at the end of the cycle, making it weaker because of abnormal and complicated magnetic polarities. An initial strongly positive D ends up with a strongly negative value. The flare-poor AR 12674 has a greater contribution to the long-term axial dipole moment than the flare-rich AR 12673. We then carry out a statistical analysis of ARs larger than 800 μHem from 1976 to 2017. We use the flare index FI and define an axial dipole moment index DI to quantify the effects of each AR on space weather and space climate, respectively. Whereas the FI has a strong dependence on the magnetic configuration, the DI shows no such dependence. The DI is mainly determined by the latitudinal location and the latitudinal separation of the positive and negative magnetic fluxes of the ARs. Simple ARs have the same possibility as complex ARs to produce big DI values affecting space climate

Active-region Tilt Angles: Magnetic versus White-light Determinations of Joy's Law

The axes of solar active regions are inclined relative to the east-west direction, with the tilt angle tending to increase with latitude ("Joy's law"). Observational determinations of Joy's law have been based either on white-light images of sunspot groups or on magnetograms, where the latter have the advantage of measuring directly the physically relevant quantity (the photospheric field), but the disadvantage of having been recorded routinely only since the mid-1960s. White-light studies employing the historical Mount Wilson (MW) database have yielded tilt angles that are smaller and that increase less steeply with latitude than those obtained from magnetic data. We confirm this effect by comparing sunspot-group tilt angles from the Debrecen Photoheliographic Database with measurements made by Li and Ulrich using MW magnetograms taken during cycles 21-23. Whether white-light or magnetic data are employed, the median tilt angles significantly exceed the mean values, and provide a better characterization of the observed distributions. The discrepancy between the white-light and magnetic results is found to have two main sources. First, a substantial fraction of the white-light "tilt angles" refer to sunspots of the same polarity. Of greater physical significance is that the magnetograph measurements include the contribution of plage areas, which are invisible in white-light images but tend to have greater axial inclinations than the adjacent sunspots. Given the large uncertainties inherent in both the white-light and the magnetic measurements, it remains unclear whether any systematic relationship exists between tilt angle and cycle amplitude during cycles 16-23

HUNCHEST-II contributes to a shift to earlier-stage lung cancer detection: final results of a nationwide screening program

The introduction of low-dose CT (LDCT) altered the landscape of lung cancer (LC) screening and contributed to the reduction of mortality rates worldwide. Here we report the final results of HUNCHEST-II, the largest population-based LDCT screening program in Hungary, including the screening and diagnostic outcomes, and the characteristics of the LC cases.A total of 4215 high-risk individuals aged between 50 and 75 years with a smoking history of at least 25 pack-years were assigned to undergo LDCT screening. Screening outcomes were determined based on the volume, growth, and volume doubling time of pulmonary nodules or masses. The clinical stage distribution of screen-detected cancers was compared with two independent practice-based databases consisting of unscreened LC patients.The percentage of negative and indeterminate tests at baseline were 74.2% and 21.7%, respectively, whereas the prevalence of positive LDCT results was 4.1%. Overall, 76 LC patients were diagnosed throughout the screening rounds (1.8% of total participants), out of which 62 (1.5%) patients were already identified in the first screening round. The overall positive predictive value of a positive test was 58%. Most screen-detected malignancies were stage I LCs (60.7%), and only 16.4% of all cases could be classified as stage IV disease. The percentage of early-stage malignancies was significantly higher among HUNCHEST-II screen-detected individuals than among the LC patients in the National Koranyi Institute of Pulmonology's archive or the Hungarian Cancer Registry (p < 0.001).HUNCHEST-II demonstrates that LDCT screening for LC facilitates early diagnosis, thus arguing in favor of introducing systematic LC screening in Hungary.HUNCHEST-II is the so-far largest population-based low-dose CT screening program in Hungary. A positive test's overall positive predictive value was 58%, and most screen-detected malignancies were early-stage lesions. These results pave the way for expansive systematic screening in the region.• Conducted in 18 medical facilities, HUNCHEST-II is the so far largest population-based low-dose CT screening program in Hungary. • The vast majority of screen-detected malignancies were early-stage lung cancers, and the overall positive predictive value of a positive test was 58%. • HUNCHEST-II facilitates early diagnosis, thus arguing in favor of introducing systematic lung cancer screening in Hungary