@article{e30324f40ad549eba57a40859bdc4cbd,
title = "Estimates of Current Helicity and Tilt of Solar Active Regions and Joy{\textquoteright}s Law",
abstract = "Abstract: The tilt angle, current helicity and twist of solar magnetic fields can be observed in solar active regions. We carried out estimates of these parameters by two ways. Firstly, we consider the model of turbulent convective cells (super-granules) which have a loop floating structure towards the surface of the Sun. Their helical properties are attained during the rising process in the rotating stratified convective zone. The other estimate is obtained from a simple mean-field dynamo model that accounts magnetic helicity conservation. The both values are shown to be capable to give important contributions to the observable tilt, helicity and twist.",
keywords = "Sun: magnetic field: sunspots: tilt, twist, helicity, turbulence: mean-field magnetohydrodynamics",
author = "K. Kuzanyan and N. Kleeorin and I. Rogachevskii and D. Sokoloff and H. Zhang",
note = "Funding Information: Stimulating discussions with participants of the NORDITA program on “Solar Helicities in Theory and Observations: Implications for Space Weather and Dynamo Theory” (March 2019) are acknowledged. NK, KK, IR would like to acknowledge the hospitality of NORDITA for this and earlier occasions where this work has been outlined and developed. Private communications with late David Moss are acknowledged. The work of KK concerning the tilt and twist computations was supported by the grant from the Russian Science Foundation (RNF 18-12-00131) at the Crimean Astrophysical Observatory. DS would like to acknowledge support from RFBR grant 18-02-00085. The observational estimates of helicity and twist are obtained due to collaboration of IZMIRAN team with National Astronomical Observatories of China, Key Laboratory for Solar Astivity, Chinese Academy of Sciences, supported in part by CAS PIFI visiting program and RFBR of Russia—NNSF of China joint grant 19-52-53045 GFEN.a. HZ would also like to acknowledge support by grants from the National Natural Science Foundation of China (NSFC 11 673 033, 11 427 803, 11 427 901, 12073040, 120730041) and by Huairou Solar Observing Station, Chinese Academy of Sciences. Funding Information: Stimulating discussions with participants of the NORDITA program on “Solar Helicities in Theory and Observations: Implications for Space Weather and Dynamo Theory” (March 2019) are acknowledged. NK, KK, IR would like to acknowledge the hospitality of NORDITA for this and earlier occasions where this work has been outlined and developed. Private communications with late David Moss are acknowledged. The work of KK concerning the tilt and twist computations was supported by the grant from the Russian Science Foundation (RNF 18-12-00131) at the Crimean Astrophysical Observatory. DS would like to acknowledge support from RFBR grant 18-02-00085. The observational estimates of helicity and twist are obtained due to collaboration of IZMIRAN team with National Astronomical Observatories of China, Key Laboratory for Solar Astivity, Chinese Academy of Sciences, supported in part by CAS PIFI visiting program and RFBR of Russia—NNSF of China joint grant 19-52-53045 GFEN.a. HZ would also like to acknowledge support by grants from the National Natural Science Foundation of China (NSFC 11 673 033, 11 427 803, 11 427 901, 12073040, 120730041) and by Huairou Solar Observing Station, Chinese Academy of Sciences. Publisher Copyright: {\textcopyright} 2020, Pleiades Publishing, Ltd.",
year = "2020",
month = dec,
day = "1",
doi = "10.1134/S0016793220080149",
language = "English",
volume = "60",
pages = "1032--1037",
journal = "Geomagnetism and Aeronomy",
issn = "0016-7932",
publisher = "Pleiades Publishing",
number = "8",
}