Influence of the moon on the earth’s magnetosphere at various phases of a solar activity cycle

We studied the dependence of the A _p -index describing the geomagnetic disturbance on the Moon’s phase. We processed available data for cycles 20–23 of the solar activity by the epoch super-position method. We discovered that, in the declining branch of the solar cycle, the highest values of the A _p -index relative to an average value are observed near new moon. The difference of the A _p -index values for new moon and full moon is approximately 18%. In the branch of increase and maximum of the solar cycle, we observed minimum values of the A _p -index during several days before full moon, and maximum values of the A _p -index take place during several days after full moon. The conclusion follows from this that the mechanism of the Moon’s effect on the earth’s magnetosphere is different essentially for intervals near new moon and full moon.     

Quasi-synchronism of bursts in solar coronal structures in the Mg XII 0.84-nm line from CORONAS-F/SPIRIT experimental data

Based on CORONAS-F/SPIRIT images of the Sun in the MgXII 0.84-nm line, we have performed photometric measurements and investigated the time dependence of the surface brightness for fragments of ten active regions. Continuous observations were carried out on March 3–4, 2002, for about 19 h when the satellite moved in shadowless orbits. The interval between the images was, on average, about 1 min. A time correlation has been found between the brightness variations in some pairs of high-temperature regions spaced from 10° to 106° apart. We have analyzed the statistical characteristics of the temporal distribution of bursts: the observed nonuniformity of the distribution was found to be impossible for a random Poisson process. To identify sympathetic (induced) bursts, we have studied the connections in the form of magnetic loops between active regions using CORONAS-F/SPIRIT and SOHO/EIT solar images. The most probable delays between events (X-ray bursts) in various active regions have been estimated. By assuming that the disturbance propagates along the coronal loops connecting active regions, we have estimated the propagation velocity of the disturbance, ～1700 km s^?1. In the period under study, the active regions in which a large number of bursts were observed lay along the periphery of a developing equatorial coronal hole. We have concluded that the simultaneous emergence of new magnetic fluxes in the photosphere was responsible for most of the quasi-synchronous events on March 3–4, 2002. We have calculated the physical conditions in coronal loops by assuming that the propagation of magnetohydrodynamic waves in the corona could be responsible for the appearance of connected events.     

The 156-day quasi-periodicity in solar indices

This paper investigates a series of daily solar indices: the sunspot number W (1900–2008), solar flux at 2800 MHz F _10.7 (1947–2008), and a number of X-ray flares N _x (1981–2008). The methods of Fourier and wavelet analysis are used to reveal the so-called 156-day Rieger-type periodicity (RTP). The W index is observed to have a statistically significant RTP amplitude in the neighborhood of the solar maxima in most of the solar cycles under study, except for cycles 14, 15, and 23. The 156-day peak is observed to have its largest power during the declining phase of cycle 16, at the maximum of cycle 21, and during the increasing phase of cycles 20 and 23. Statistically significant RTPs are also observed at the minima of cycles 17, 18 and 19. We conclude that there is no stable dependence between RTP and the solar cycle. The wavelet analysis shows that the pattern of the RTP time dependence for the F _10.7 index is almost identical to that of the W index. The correlation coefficient between the RTP curves is 0.95. The correlation coefficients for the pairs of indices W-N _x and F _10.7-N _x are 0.36 and 0.32, respectively. No time lags are found between the RTP starting points for different indices. Thus, the 156-day quasi-periodicity involves, almost simultaneously, events that occur in active regions of the solar atmosphere at different heights. This paper discusses the possible nature of RTP.     

Solar chromosphere in the D<Subscript>3</Subscript> helium line from spectra of the eclipse of March 29, 2006

We present the processing results of slitless chromospheric spectra in a D₃ helium line obtained during the solar eclipse of March 29, 2006. A “Cascade-Photometrics 650” CCD matrix photodetector with a rate of 16 frames/s was used for the observations. Altitude distribution of absolute brightness of the helium chromosphere has been mapped in a latitude interval 30 N-10 S on the western limb. A correlation between absolute brightness of the helium chromosphere and a solar cycle phase has been confirmed. It has been revealed that the altitude distribution of helium emission has one maximum at an altitude of approximately 2000 km. In the lower chromosphere, helium emission is undetectable. This confirms our assumption about absence of an additional maximum at 300 km in the D₃ line brightness distribution in the chromosphere during sunspot maximum periods. The results also prove that X-ray coronal radiation with λ < 6 nm is the source of helium excitation in the lower chromosphere.     

Wave moment geodynamics

The work presents a review of natural-science representations on the rotary motion of matter and its piecewise structure. Development of dense GPS-networks allowed to experimentally confirm the concept of block structures of the geophysical environment and to prove rotary character of block movement. An analysis of both the migration of earthquake sources and the movement of sections of tectonic plates’ borders has allowed to reveal general properties of such movements and to prove their wave nature. It is shown that within the limits of rotational model, blocks and plates are interconnected among themselves by the elastic long-range fields forming a uniform planetary geodynamic field. It is offered to use the geodynamic solutions of rotational model in the one class of phenomena as a basis at the construction of a new geological paradigm — wave moment geodynamics.     

Global warming mitigation by sulphur loading in the stratosphere: dependence of required emissions on allowable residual warming rate

An approach to mitigate global warming via sulphur loading in the stratosphere (geoengineering) is studied, employing a large ensemble of numerical experiments with the climate model of intermediate complexity IAP RAS CM. The model is forced by the historical+SRES A1B anthropogenic greenhouse gases+tropospheric sulphates scenario for 1860–2100 with additional sulphur emissions in the stratosphere in the twenty-first century. Different ensemble members are constructed by varying values of the parameters governing mass, horizontal distribution and radiative forcing of the stratospheric sulphates. It is obtained that, given a global loading of the sulphates in the stratosphere, among those studied in this paper latitudinal distributions of geoengineering aerosols, the most efficient one at the global basis is that peaked between 50°N and 70°N and with a somewhat smaller burden in the tropics. Uniform latitudinal distribution of stratospheric sulphates is a little less efficient. Sulphur emissions in the stratosphere required to stop the global temperature at the level corresponding to the mean value for 2000–2010 amount to more than 10 TgS/year in the year 2100. These emissions may be reduced if some warming is allowed to occur in the twenty-first century. For instance, if the global temperature trend S _g in every decade of this century is limited not to exceed 0.10 K/decade (0.15 K/decade), geoengineering emissions of 4–14 TgS/year (2–7 TgS/year) would be sufficient. Even if the global warming is stopped, temperature changes in different regions still occur with a magnitude up to 1 K. Their horizontal pattern depends on implied latitudinal distribution of stratospheric sulphates. In addition, for the stabilised global mean surface air temperature, global precipitation decreases by about 10%. If geoengineering emissions are stopped after several decades of implementation, their climatic effect is removed within a few decades. In this period, surface air temperature may grow with a rate of several Kelvins per decade. The results obtained with the IAP RAS CM are further interpreted employing a globally averaged energy–balance climate model. With the latter model, an analytical estimate for sulphate aerosol emissions in the stratosphere required climate mitigation is obtained. It is shown that effective vertical localisation of the imposed radiative forcing is important for geoengineering efficiency.     

Strong Tidal Mixing and Ventilation of Cold Intermediate Water at Kashevarov Bank, Sea of Okhotsk

Tidal mixing at the Kashevarov Bank, Sea of Okhotsk, has been investigated using observations of bottom pressure and currents. The tides are dominated by the diurnal constituents. The water motion over the Bank is predominantly controlled by strong diurnal tidal currents, which bring cold water on the bank from its source, a cold intermediate layer. The temperature fluctuations are about 1.2°C at the southern edge of the bank. The maximum observed velocity is about 164 cm/s at the top of the bank. A superposition of the original diurnal constituents K₁ and O₁ reveals a strong fortnightly (M_f) variability of the current speed. Tidal-induced mixing is responsible for ventilation of the cold intermediate layer of the Sea of Okhotsk. Strong tidal mixing creates a well-defined tidally mixed front around the bank. This front acts like a barrier separating well-mixed water on the bank from stratified water on its flanks. There is a residual current of the order of 10 cm/s.