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Plamy słoneczne podczas Minimum Maundera

100%

Rek R.

nr 3

91–130

The first sunspot had been observed with use of a telescope in 1610 by Thomas Harriot, in England. Observations later made by Galileo Galilei and Christoph Scheiner allowed them to publish detailed reviews of the studies. Very important place in the early history of solar investigations is occupied by Johan Hevelius with his catalogue and pictures of sunspot routes on the solar disc. His research had realized in the years 1642–1644 were the last before the so-called Maunder Minimum that started around 1645 and had lasted until 1715 or 1717 year. The hypothetical physical phenomenon propagated by Gustav Spörer at the end of the 19th century and the observations of sunspots that were discerned during this long minimum are discussed in detail. This paper presents the history of these solar research and includes some analyses that allowed me to compare the level of solar activity during the second part of the 17th century with other periods. Some observations of sunspots, discerned in the years 1672–1713 and later by other scientists, who were interested in investigations of the heliolatitude changes of these phenomena in the past, were omitted by Spörer on his published list of spots. A large part of other descriptions was connected with an astrometric measurements and misinterpreted as the solar surface investigations. As a result, a false opinion about the level of solar activity during the Maunder Minimum became a natural explanation for the solar behaviour and diffe¬rent terrestrial phenomena as variability of the radiocarbon isotope abundance in tree-rings. Additionally, this paper presents recently found archival descriptions of the solar spots and descriptions of large sunspots that were visible in the years of deep phase of Minimum, before the year 1700. A development of the Minimum idea, with use of the auroral displays discerned in the second part of the 17th century and the first two decades of the next century, is also shortly discussed. The auroral cyclicity appears to confirm more typical course of the solar activity during these years.

A palaeotemperature record for the Finnish Lakeland based on microdensitometric variations in tree rings

75%

Helama S. , Vartiainen M. , Holopainen J. , Mäkelä H. M. , Kolström T. , Meriläinen J.

2014

tom Vol. 41, no. 3

265--277

X-ray based tree-ring data of maximum latewood densities (MXD) was combined for south-eastern Finland. This data originated from subfossil and modern pine (Pinus sylvestris L.) materials comprising a continuous dendroclimatic record over the past millennium. Calibrating and verifying the MXD chronologies against the instrumental temperature data showed a promising opportunity to reconstruct warm-season (May through September) temperature variability. A new palaeotemperature record correlated statistically significantly with the long instrumental temperature records in the region and adjacent areas since the 1740s. Comparisons with tree-ring based (MXD and tree-ring width) reconstructions from northern Fennoscandia and northern Finland exhibited consistent summer temperature variations through the Medieval Climate Anomaly, Little Ice Age, and the 20th century warmth. A culmination of the LIA cooling during the early 18th century appeared consistently with the Maunder Minimum, when the solar activity was drastically reduced. A number of coolest reconstructed events between AD 1407 and 1902 were coeval to years of crop failure and famine as documented in the agro-historical chronicles. Results indicate an encouraging possibility of warm-season temperature reconstructions using middle/south boreal tree-ring archives to detail and enhance the understanding of past interactions between humans, ecosystems and the earth.