Bremen 2017 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 13: Erdnaher Weltraum
EP 13.2: Talk
Thursday, March 16, 2017, 17:00–17:15, GW2 B2880
New calibration of the group sunspot number series using a non-linear non-parametric method — •Theodosios Chatzistergos1, Ilya G. Usoskin2,3, Gennady A. Kovaltsov4, Natalie A. Krivova1, and Sami K. Solanki1,5 — 1Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany — 2Space Climate Research Unit, University of Oulu, Finland — 3Sodankylä Geophysical Observatory, University of Oulu, Finland — 4Ioffe Physical-Technical Institute, St.Petersburg, Russia — 5School of Space Research, Kyung Hee University, Yongin, Republic of Korea
Sunspot observations provide a critical insight into the changes in solar activity and variability on decadal to centennial timescales. This is essential to understand the solar influence on Earth's climate. Such data have been recorded almost continuously since 1610. However the observations have been done by different observers, with different instruments and techniques, that need to be calibrated to a reference set. Numerous attempts have been made to calibrate these data, mostly employing a simple linear scaling, which is however known to be not appropriate. We present here a revisited calibration of the group sunspot number series based on a direct non-parametric non-linear method. We selected a number of long and stable records as backbones, and calibrated all other individual observers of the corresponding periods to these backbones using direct probability distribution functions. Using a similar approach, the backbones were then merged into the final record, which is calibrated to the reference data set. The final series supports the existence of the Modern Grand Maximum.