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pro vyhledávání: '"Svalgaard, Leif"'
Through meticulous daily observation of the Sun's large-scale magnetic field the Wilcox Solar Observatory (WSO) has catalogued two magnetic (Hale) cycles of solar activity. Those two (~22-year long) Hale cycles have yielded four ($\sim$11-year long)
Externí odkaz:
http://arxiv.org/abs/2208.09026
Autor:
Svalgaard, Leif
The long-standing disparity between the sunspot number record and the Hoyt and Schatten (1998, H&S) Group Sunspot Number series was initially resolved by the Clette et al. (2014) revision of the sunspot number and the group number series. The revisio
Externí odkaz:
http://arxiv.org/abs/2011.05356
Autor:
Svalgaard, Leif, Hathaway, David H.
The Waldmeier Effect is the observation that the rise time of a sunspot cycle varies inversely with the cycle amplitude: strong cycles rise to their maximum faster than weak cycles. The shape of the cycle and thus the rise time does not depend on the
Externí odkaz:
http://arxiv.org/abs/2011.01330
Autor:
Svalgaard, Leif
Prediction of solar cycle is an important goal of Solar Physics both because it serves as a touchstone for our understanding of the sun and also because of its societal value for a space faring civilization. The task is difficult and progress is slow
Externí odkaz:
http://arxiv.org/abs/2010.02370
Autor:
Svalgaard, Leif
Solar surface magnetic field seems to be able to explain variations in Total Solar Irradiance on timescales from hours to decades. Using magnetograms from spacecraft (MDI and HMI) and ground-based observatories (MWO and WSO) I build a composite datas
Externí odkaz:
http://arxiv.org/abs/1812.09301
Autor:
Svalgaard, Leif
A nine-millennia reconstruction of decadal sunspot numbers derived from 10Be and 14C terrestrial archives for 6755 BC to 1885 AD has been extended to the present using several other messengers (Observed Sunspot Number, Group Number, range of the diur
Externí odkaz:
http://arxiv.org/abs/1810.11952
Autor:
Svalgaard, Leif, Schatten, Kenneth H.
We identify several pairs of 'equivalent' observers defined as observers with equal or nearly equal 'observational threshold' areas of sunspots on the solar disk as determined by the 'Active Days Fraction' method [e.g. Willamo et al., 2017]. For such
Externí odkaz:
http://arxiv.org/abs/1706.01154
Autor:
Svalgaard, Leif
We show that the Active-Day-Fraction calibration method (Willamo et al. [2017]) fails for Gustav Sp\"orer's sunspot group observations. Sp\"orer was labeled a 'perfect observer' on account of his 'observational threshold SS area' being determined to
Externí odkaz:
http://arxiv.org/abs/1705.06089
Autor:
Svalgaard, Leif, Schatten, Kenneth H.
Recent work on improving and revising estimates of solar activity [Clette et al., 2014] has resulted in renewed interest in what has been called the longest running 'Science Experiment'. We compare four reconstructions of solar activity as reflected
Externí odkaz:
http://arxiv.org/abs/1705.02024
Autor:
Svalgaard, Leif, Schatten, Kenneth H.
We discuss recent papers very critical of our Group Sunspot Number Series (Svalgaard & Schatten [2016]). Unfortunately, we cannot support any of the concerns they raise. We first show that almost always there is simple proportionality between the gro
Externí odkaz:
http://arxiv.org/abs/1704.07061