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Reconstruction of the solar activity to 11,000 years BP and possible long-term periodicities
Střeštík, Jaroslav
Observations of solar activity (Wolf sunspot numbers) last only about 250 years, moreover, from sporadic observations the solar activity can be estimated approximately to the year 1500. In addition to the well-known eleven-year period some long-term periods seem to take place. This means that the values at the maxima of 11-yr solar cycles in certain periods are higher than those in other ones. Based on the analysis of dust fallout containing radioactive elements, conserved in glaciers, some authors reconstructed the solar activity first one millennium back, and later more millennia back. The longest series begins 9000 years B. C. and these data are published. Strangely, most authors of these the reconstructions do not look for possible periodicities, or only marginally. Here the possible periodicities obtained from a series of 11,000 years long have been presented. The results suggest a superlong periodicity with the length about 6500 years, on the other hand, they do not confirm variations with the length between 100 and 200 years, which are not persistent.
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Increase in Winter Air Temperatures in the Czech Republic between 1961 and 2010
Střeštík, Jaroslav ; Rožnovský, J. ; Štěpánek, Petr ; Zahradníček, Pavel
Based on the analysis of average monthly air temperatures between 1961 and 2010 it can be statistically proven that there is an increasing trend. The actual level of increase, however, is different for each season and is also specific for a particular region – there are differences between Bohemia and Moravia. In the summer, the average monthly air temperatures rise more significantly in Moravia, where there is a higher number of stations with increase of over 1°C compared to Bohemia. This is also true for the spring, for which the difference is not so profound, and is yet smaller in the autumn. In contrast, in the winter there is a more significant increase in Bohemia, where most stations show an increase of over 0.5°C. In Moravia the increase is usually only around 0.3 to 0.4°C. Differences between the increases of average air temperature can also be seen across the individual winter months. Highest increase was found in January, where some stations in Bohemia show an increase of over 1°C, a value that was not observed in Moravia, where some stations have an increase of less than 0.8°C. In December and February, the level of increase in general is much smaller. However, given the predicted increase of air temperatures in the future in general, it can be expected that in the upcoming decades the number of warm winters will increase. Such increase of air temperatures in the winter is likely to have negative impacts for the agriculture.
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The change of the rain factor on the net of stations in the Czech Republic during 1961-2010
Střeštík, Jaroslav ; Rožnovský, J. ; Štěpánek, P. ; Zahradníček, P.
Precipitation totals do not express precisely the humidity conditions in the landscape. Therefore the Lang’s rain factor, constructed from monthly and annual average temperatures and precipitation totals on 267 stations in the Czech Republic during 1961-2010, has been used here. Its values are very different at different stations, the lowest they are at South Moravia and Labe lowlands. Its average for the whole territory displays a slow decrease during the 50 years, supplemented by strong fluctuations. The strongest decrease appears in the Northern boundary mountains. The same factor calculated only for summer displays stronger differences between highlands and lowlands, especially in South Moravian ones. Stronger decrease at North Moravia, especially in mountains, and very weak decrease at other parts takes place.
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School vacancies from the point of view of the annual course of selected meteorological parameters
Střeštík, Jaroslav
School vacancies in our country have lasted from July 1st till August 31st since more than hundred years. There is, however, a question, whether this period is the best one. The course of the air temperatures show that the warmest period in the year occurs between the half June and half August. On the other hand, rains are less frequent in August than in June. In view of the fact that the annual course of temperatures in individual years approaches to the long-term one more than that of precipitation, and with respect to some other factors, it results that the most suitable period for school vacancies starts on June 20th. In that case, the vacancies and subsequent school year should start always in Monday.
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Increase of annual and seasonal air temperatures in the Czech Republic during 1961-2010
Střeštík, Jaroslav ; Rožnovský, J. ; Štěpánek, P. ; Zahradníček, P.
Using the monthly means of air temperatures at 267 stations in the Czech Republic, the long-term change has been estimated at each station for the last 50 years. Annual mean temperatures for the whole country show a considerable increase, more pronounced than that for global temperature, however, supplemented by strong fluctuations from year to year. Long-term changes in air temperatures at different stations and in different regions vary. Stronger increase in air temperatures can be seen in Bohemia, whereas in Moravia temperature increase is not so significant. This difference is more pronounced in the winter, whereas in the summer, the differences are smaller and perhaps of opposite nature. This means that the continentality of the climate in Moravia increases, while in Bohemia it very slightly decreases. Long-term changes depend only marginally on the absolute values of annual mean temperatures at the respective station. The increase of autumn temperatures is considerably lower than that of other seasons.
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Possible correlations between geomagnetic activity and global air temperature
Střeštík, Jaroslav
Annual values of the geomagnetic activity indices aa have been compared with the annual mean values of global air temperature during 1850-2012. Despite of a big noise level a significant positive correlation takes place. However, it only reflects a very similar long-term change occurring in both investigated quantities, which must not have a common origin. Short periodical changes with periods of years or decades are at both quantities quite different and their correlation is negligible. When shorter parts with the length of about some decades have been compared, resulting correlations were different. The significant correlation for the whole period is therefore not persistent. No influence of the geomagnetic activity on global temperature in shorter time dimensions has been proved and therefore it is not possible to use any estimate of a possible course of the geomagnetic activity for a prediction of the global temperature in the future. Using the temperature data from the individual stations instead of the global ones different correlations can be obtained but even these are not persistent. The same result will follow using any other selection of shorter intervals.
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