Oleg M. Raspopov

Arctic ozone abundance and solar proton events

In this study it is documented for the first time that the atmospheric ozone column density is decreased during solar proton events, GLEs (Ground Level Events), events with protons having energy exceeding 50 MeV and penetrating down to the ground. The ozone decrease was significant at the polar cap stations, Longyearbyen and Barentsburg at 78° N, whereas it was not detectable at the auroral zone stations Murmansk (69° N) and Tromso (70° N). The duration of the depletion was limited to the days of the proton precipitation, and the depletion may be explained by the ability of energetic protons to produce nitric and hydrogen oxides in the stratosphere and their catalytic reactions with ozone. Similar events are identified in the Antarctic.

Ozone “miniholes” initiated by energetic solar protons

Abstract In this study, it is shown that during four Solar Proton Events (SPE), mostly of the Ground Level Event (GLE) type (May 1990, September and October 1989, and March 1989), inside the polar cap in the Arctic (or the Antarctic) short-term depletions were observed (up to 20%) in the ozone total content. These depletions or so-called ozone “miniholes” seem to be caused by energetic solar protons with energies of 150–300 MeV. For May 1990, the gas phase photochemical model includes only 1% ozone depletion compared with 18% observed at Barentsburg (Svalbard), and for none of the other events can homogeneous processes explain the observed depletion. The problem seems to be solved considering heterogeneous reactions in the presence of increased amounts of aerosol particles in the stratosphere which may be triggered by penetrating solar protons, or through an additional decrease of temperature, or through an increase of volume electric charge in the stratosphere (or even troposphere).

CLIMATIC VARIABILITY ALONG A NORTH–SOUTH TRANSECT OF FINLAND OVER THE LAST 500 YEARS: SIGNATURE OF SOLAR INFLUENCE OR INTERNAL CLIMATE OSCILLATIONS?

Abstract. Statistical analysis of a multi‐centennial dendrochronological proxy dataset of regional climate, constructed across the latitudinal gradient of 1000 km, was performed. It was shown that centennial (c. 100 year), tri‐decadal (27‐32 year), bi‐decadal (17‐23 year) and decadal (9‐13 year) periodicities governed the climate variability in Finland over the last five centuries. Despite the fact that many of the climatic periodicities bore great resemblance to periodicities of solar cycles, little evidence of actual solar influence on Finnish climate was found when the climate proxy records were subjected to linear correlation analysis with sunspot numbers. Highly non‐linear response of Northern Fennoscandian climate to solar forcing might be a cause of this result, as well as influence of terrestrial climatic processes (e.g. effect of other forcing factors and internal dynamics of regional climate). Our results show that the presence of internal climate variability at time‐scales of solar activity might distort the solar signature in climatic data and complicate its detection.

Simultaneous occurrence of IPDP and auroral absorption as indication of joint westward drift of protons and electrons

Abstract The dynamics of the intervals of pulsation of diminishing periods (IPDP) generation region and that of the auroral absorption (AA) are compared. It is known that IPDP is the manifestation of the ion-cyclotron instability due to precipitation and drift of protons and AA is the result of electron precipitation. The westward movement in space and time of the AA and IPDP generation region was revealed. This is the first experimental confirmation of the joint westward drift of the electron and proton in the form of neutral clouds in the magnetosphere during an auroral substorm.

Long-term variations in the flux of cosmogenic isotope 10Be over the last 10000 years: Variations in the geomagnetic field and climate

A spectral analysis of data on the flux of cosmogenic 10Be in ice core samples from the Central Greenland (project GRIP) over the last 10 thousand years have been carried out. It has been shown that the 10Be flux varies cyclically; the most significant cycle is of about 2300 years. Variations in the position of the virtual geomagnetic pole over 8000 years have been analyzed. Significant components, pointing to the cyclic variation in the position of the geomagnetic pole with a period of about 2300 years, have been revealed in a periodogram of the virtual geomagnetic pole longitude. In addition to the nearly 2300-year-long cycle, some lines are observable in the 10Be flux periodogram, which can be considered as a manifestation of the 1000-year-long cycle of the 10Be deposition rate on the ice surface. The relationship between the cyclicity of the geomagnetic pole position and the 10Be flux is discussed.

Manifestation of variations in solar activity 70-45 Ma ago

Unique paleoenvironmental records (ring widths of fossil trees) with a temporal resolution of 1 year are analyzed with the aim of revealing periodicities in climatic processes during the time interval of 70-45 Ma ago. The periodicities thus obtained are compared with the solar and climatic periodicities observed at present. It is shown that quasi-bicentennial and quasi-secular periodicities that can be attributed to the influence of solar Suess-de Vries and Gleissberg cycles manifest themselves in the most intense manner in climatic oscillations in the past (70-45 Ma ago). The spectra of the paleoclimate data exhibit periodicities that are typical of solar activity, i.e., the quasi-20-year (Hale cycle) and 11-year (Schwabe cycle) ones derived from the instrumental data and historical observations of sunspots. It can be concluded that analyzing climatic periodicities obtained by paleodendrochronology gives information on the solar periodicity that cannot be achieved by other methods. The revealed periodicities are similar in values to the present-day periodicity of solar activity.