Monitoring the 2004 andesitic block-lava extrusion at Volcán de Colima,México from seismic activity and SO2 emission

The 2004 andesitic block-lava extrusion at Volcán de Colima, México was accompanied and followed by numerous seismic signals associated with rockfalls, pyroclastic flows and explosive events. We analyze temporal variations in the number of rockfalls and explosions, the seismic signal duration of rockfalls and the energy of the explosion and compare this with both the rate of magma discharge and SO₂ emission. Characteristics of seismic signals and SO₂ emission are compared with those observed during the 1998–1999 Volcán de Colima block-lava extrusion. For both eruptions, the explosive activity was low during the lava extrusion and increased after its termination. The variation in the daily number and the total duration of rockfall seismic signals gives a good reflection of the development of the lava emission process. An increase in magmatic degassing (SO₂ flux) was observed some days before the onset of lava extrusion. The degassing strongly decreased some days before the peak in the rate of the 1998–1999 lava emission but reached its peak together with the peak in the rate of the 2004 lava emission. These features of seismic activity and SO₂ emission demonstrate that they are good tools for monitoring the extrusion process.     

Changes in the Probability of Heavy Precipitation: Important Indicators of Climatic Change

A simple statistical model of daily precipitation based on the gamma distribution is applied to summer (JJA in Northern Hemisphere, DJF in Southern Hemisphere) data from eight countries: Canada, the United States, Mexico, the former Soviet Union, China, Australia, Norway, and Poland. These constitute more than 40% of the global land mass, and more than 80% of the extratropical land area. It is shown that the shape parameter of this distribution remains relatively stable, while the scale parameter is most variable spatially and temporally. This implies that the changes in mean monthly precipitation totals tend to have the most influence on the heavy precipitation rates in these countries. Observations show that in each country under consideration (except China), mean summer precipitation has increased by at least 5% in the past century. In the USA, Norway, and Australia the frequency of summer precipitation events has also increased, but there is little evidence of such increases in any of the countries considered during the past fifty years. A scenario is considered, whereby mean summer precipitation increases by 5% with no change in the number of days with precipitation or the shape parameter. When applied in the statistical model, the probability of daily precipitation exceeding 25.4 mm (1 inch) in northern countries (Canada, Norway, Russia, and Poland) or 50.8 mm (2 inches) in mid-latitude countries (the USA, Mexico, China, and Australia) increases by about 20% (nearly four times the increase in mean). The contribution of heavy rains (above these thresholds) to the total 5% increase of precipitation is disproportionally high (up to 50%), while heavy rain usually constitutes a significantly smaller fraction of the precipitation events and totals in extratropical regions (but up to 40% in the tropics, e.g., in southern Mexico). Scenarios with moderate changes in the number of days with precipitation coupled with changes in the scale parameter were also investigated and found to produce smaller increases in heavy rainfall but still support the above conclusions. These scenarios give changes in heavy rainfall which are comparable to those observed and are consistent with the greenhouse-gas-induced increases in heavy precipitation simulated by some climate models for the next century. In regions with adequate data coverage such as the eastern two-thirds of contiguous United States, Norway, eastern Australia, and the European part of the former USSR, the statistical model helps to explain the disproportionate high changes in heavy precipitation which have been observed.     

Reconstruction of radiation fluxes at the ocean surface from NOAA satellite data

Algorithms for obtaining operative information on the fluxes of the total solar radiation and radiation balance at the ocean surface are developed and realized on the basis of satellite observations within the spectral ranges 0·725–1·1 and 10·3–11·3 m at arbitrary scanning angles. For the 10-day and monthly values, the reconstruction errors remain at the level of the accuracy of the shipboard measurements. The atlas of charts of the above parameters (grid 0·5°×0·5°) is compiled using data obtained by the RVAkademik Vernadsky in the Atlantic Ocean during 1986–1989.Translated by Mikhail M. Trufanov.     

Investigation of the oceanic cloudiness according to the data of satellite observations in the spectral range 10.3–11.3 μm

The temperature of waters in the upper layer of the ocean and effective cloudiness (cloudiness with simultaneous indication of its amount and optical density) are important characteristics of the natural environments. They determine the greenhouse effects and the energy of the ocean and atmosphere, and regulate climate. The satellite data on these characteristics enable one to reconstruct all components of the radiation, heat, and water budgets in the ocean–atmosphere system and study their intra- and interannual variations. We describe the procedures of evaluation of the effective cloudiness according to the sea-surface temperature and the radiation temperature in the spectral range 10.3–11.3 μm. The development of these investigations is connected with the advances in satellite hydrophysics: the satellite data become more and more accurate, regular, and global.     

High-Resolution Modeling of Semidiurnal Internal Tidal Waves in the Laptev Sea in the Ice-Free Period: Their Dynamics and Energetics

Izvestiya, Atmospheric and Oceanic Physics - The QUODDY-4 three-dimensional finite-element hydrostatic model has been used to reproduce the spatial distributions of dynamic and energetic...     

Helium-volume dynamics of Upper Freeport coal powder and lumps

Exposure to 7 MPa of helium at room temperature alters the texture of Upper Freeport coal in a lump form. The differences in texture and porosity between coal powder and lumps may affect the transport and interaction of fluids and coal. In this work, the information about the coal texture and micro- and meso-porosity was obtained via the BET, BJH, and Dubinin–Astakhov analyses. We further investigated the free-fluid-phase volume (free-volume) effects due to helium interaction with the powder and the lumps. During the manometric experiment, helium penetration into the dry coal matrix resulted in slow relaxation of pressure. After exposure of coal to helium, there have been no significant changes of the macroscopic dimensions observed and the relaxation process can be attributed to microscopic ‘free-volume’ effects. Evolution of the sorption–desorption rates indicates that exposure to helium may change the texture and apparent (helium) density of dry coal.     

Hierarchy of Factors of Seismic Danger in Four Towns in Colima State,México

The RADIUS methodology is applied to study the hierarchy of the factors of seismic danger in four towns of Colima state, México. These towns are situated near the western coast of Pacific ocean, within zone of highest seismic risk. The 31 indicators and five factors (Hazard, Exposure, Vulnerability, External context and Emergency response and recovery capability) of seismic danger were calculated. Their comparative analysis showed that the social factors of seismic danger might compete and even prevail over the natural factors. The recent earthquake of 21 January 2003 (Intensity up to VII–VIII MM in Colima state) was used to discuss some problems of application of RADIUS methodology in various locations, such as in Latin America.     

Mv Lyr: Transition from Low to High Brightness State

We present results of multicolour photometry of the nova-like binary MV Lyr in the years 2002–2003, corresponding to the transition of the star from its low (V = 17.8) to high (V = 12.3) brightness state. The transition lasted at most 200 days. During the first ∼50 days MV Lyr brightened at the rate 0.06 mag/day, and during the next ∼150 days at the rate 0.01 mag/day. The brightening was accompanied by a blue shift from 0.45 to 0.05 in V−R, interpreted as an increase of the accretion disk contribution to the total light. During the transition MV Lyr displayed well-known ‘quasi-orbital’ light variations and fast quasi-periodic oscillations with a typical time scale of tens of minutes.