C. Poulakos

Possible periodicities of high-speed solar plasma

We have made a statistical analysis of the monthly numbers of high-velocity solar wind streamers observed by the time period 1964–1978.The following periods have been found:(1)Eleven years, 6 and 3 months for the solar wind streamers, which have solar flares as sources.(2)Fourteen years and 36, 24, 12, 6, 4, 3 months for the number of solar wind streamers, which have coronal holes as sources.(3)Sixteen years for the total number of solar wind streamers.

PERIODICITIES OF THE NUMBER OF SOLAR FLARES FOR THE PERIOD 1966-1988

In the present paper a study is made of the mean monthly number of grouped solar flaresf for the time period 1966–1988. Corresponding dataF were taken from the catalogue published by Coffey (1989). Periodicities of 140, 120, 48, 18, 12, and 11 months as well as shorter periodicities of the order of 6 and 3 months for the solar flares have been found. The emphasis is given as far as it concerns the period of 48 months, i.e., 4 years which is for the first time revealed by the present investigation.

Long and short term variation of the 10.7 cm solar flux. The photospheric granules and the Zürich numbers

Based on diurnal values of the total radio-flux density at 10.7 cm as well as on corresponding Zürich numbers the relation giving the radio-flux as function ofR is established. The behaviour of low and high values ofR andF2800 during the time interval 1957–1976 is studied. Preliminary conclusions drawn by other investigators are confirmed. A prediction of the total radio-flux for the 22nd solar cycle is given.

Stratospheric ozone variations in the northern and the southern hemisphere during the period 1957–1990

The fluctuation and the periodicities of the total ozone layer for the period 1957–1990 is studied. Monthly total ozone data from 32 ground based stations have been analysed. It is shown that the maxima and the minima of the monthly values of total ozone for each year and for the whole period in question do not necessarily occur in March or in April and in September or October but range from March till July and from September till December respectively. Periodicities of 3, 4 and 6 months have been revealed. Finally the maxima and the minima of the total ozone data were examined. The variation of the whole phenomenon is analytically expressed with the help of an algebraic formula and can represent the observed monthly ozone values with an accuracy of 97%.

The distribution of solar flares and probable relations to biological effects

We have compared the monthly distribution of the total number of flares to the monthly mortality from cardiovascular and myocardial infarctions for the time period 1974–1983, and computed correlation coefficients. Periodicities of 3 and 5 months (150 days) have been found in both distributions.

The distribution of solar flares for the time period 1967–1985

The distribution of monthly counts of grouped solar flares Nf has been studied for the time period 1967–1985 and they have been compared to other solar activity index Rz, F2800, and F3750 i.e. intensities of solar radio flux at 2800 MHz and 3750 MHz. Seasonal variations have been found in the monthly distribution of solar flares.We have also studied the variation of the correlation coefficient for every year between NF and Rz for the time period 1967–1985. The distribution of monthly counts of grouped solar flares Nf has also been compared to the number at high velocity solar-wind streamers for the same period.

Rocket sonde-derived stratospheric temperature changes associated with a major solar cosmic ray event

A significant cooling of the upper stratosphere at high latitudes following the major solar proton event of August 1972 is reported. The observed cooling is consistent with a decrease in upper stratospheric ozone after the same proton event that has been reported by Heath,et al. (1977). It is also in agreement with the cooling predicted by tentative model calculations of radiative equilibrium temperature changes following the deozonizing effect of nitric oxides produced at high latitudes by solar protons.

A CORRELATION STUDY BETWEEN OZONE AND VOLCANIC ACTIVITY

A cross-correlation study for time-lags of ±5 yrs between eleven ground based ozone stations (1957–1985) forϕ = 40°N–75° N andλ = 30° E-114° W and five volcanic emissivity indices has shown their close connection: significant correlations well above 90% were obtained. Intepretation of these positive/negative correlations (γ) was based on the global wind circulation (aided also by a 2-D, 3-D representation betweenϕ, λ, γ), and the types of volcanic aerosols leading to heterogeneous chemical reactions with ozone.