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991.
M. B. Gokhberg G. M. Steblov S. L. Shalimov V. A. Veis E. A. Grekhova 《Izvestiya Atmospheric and Oceanic Physics》2011,47(8):929-940
Using available Russian and international Global Positioning System (GPS) network data, we studied the ionospheric response
to the M = 8.9 submarine earthquake of March 11, 2011, on the northeastern coast of Honshu Island, Japan, both near and far (about
2000 km away) from the epicenter. In the region over the epicenter, 8.7 min after the event, we detected a characteristic
signal of the total electron content (TEC) variations consisting of compression and rarefaction phases and a linear transition
zone in between, i.e., in the form of an N-type wave with a steep leading front indicating a rapid uplift of the water surface and, correspondingly, the bottom of the
ocean. The shape of the signal can be used for early tsunami warning; i.e., it may indicate the tsunamigenic character of
a submarine earthquake. We monitored the subsequent evolution of the ionospheric response as far as 2000 km from the epicenter.
It was shown that, besides the wellknown ionospheric N-type wave response to the earthquake, there is also a response in the form of an inverted N-wave, both nearby and far from the epicenter. We detected two more types of ionospheric responses far from the epicenter:
a solitary-like wave and an internal gravity wave (IGW). The detected signals have been interpreted. 相似文献
992.
Based on the scatterometer QuickScat wind data and the water-leaving radiances from the ocean color scanner SeaWiFS data for
2000–2004, we composed a pair of mean annual images of a testing site in the South Caspian Sea under conditions of west-bound
and east-bound winds corresponding to the offset and onset state of the shallows in the east of the testing site. It was established
that both the “offset” and “onset” radiances grow shorewards, but the former becomes about twice as large as the latter in
the middle of the shallows with 10–15 m of water, while their difference tends to zero at the seaward and coastal boundaries
of the shallow. These and other findings are hypothetically attributable to the inclination of the sea floor of the shallows,
due to which the surfacing of bottom sediments resuspended by the drift current takes less time under the “offset” wind conditions
than under the “onset” ones. The study’s results indicate that the effect of the bottom sediments resuspension upon the structure
of the images of the marine shallows is universal in character and needs to be taken into account to improve the bio-optical
algorithms for estimating the admixtures in the thickness of the shallows from the satellite data. 相似文献
993.
994.
Core Psd-590 (length 947 cm, water depth 124 m) penetrated the entire sequence of marine (Littorina) mud (730 cm) and stopped
in gray lacustrine (Ancylus) clays with hydrotroilitic films. The Littorina mud is gray-colored, microlaminated in the interval
of 730 to 700 cm, and dark gray with hydrotoilitic films and obscure microlamination higher in the section. According to the
diatom data, typical marine sediments begin at the level of 620 cm, while the lithological-geochemical data indicate this
change at the level of 730 cm. This level is marked by a considerable increase in the concentrations of SiO2amorph, CO2, Corg, and Mn in the sediments. In the interval of 730 to 620 cm, diatoms are represented by both freshwater and brackish-water
species. The Littorina transgression began in the form of individual flows of saline North Sea waters into the Baltic Sea,
which is evident from the microlamination and sharp peaks in the concentrations of the chemical elements. The transgression
exhibits two weakening and one strengthening (core interval of 380 to 220 cm) stages; the latter was marked by the maximal
water salinity. The post-Littorina mud contains molluscan shells and fish bones and is enriched in the fraction of 0.05–0.01
mm. The microlaminated Littorina mud was deposited during periods with stagnant conditions in the bottom water layer, while
the homogenous sediments accumulated during periods of its aeration. 相似文献
995.
996.
This paper considers the results of numerical experiments involving POLYMODE data assimilation by a barotropic model for synoptic ocean dynamics. The model's response the data assimilation for various space-time discretenesses of assimilation is studied. Results derived from the application of optimal interpolation algorithms and modified optimal filtration algorithms are compared. Qualitative similarity to the calculations carried out through the simulation modelling technique is noted. Optimal assimilation algorithms are determined, depending on the space-time discreteness used. An optimal sampling discreteness for the POLYMODE conditions is suggested.Translated by Vladimir A. Puchkin. 相似文献
997.
The problem of monitoring of the mesoscale variability of hydrophysical fields in the shelf zone is considered. The usefulness of the data available in regional information centres is discussed. The possibility of monitoring the dynamics of the oceanic fields in the tropical Atlantic encompassing separate observation sites is demonstrated using the oceanographic databank of the scientific research centre (CERESCOR) in Conakry-Rogbane as an example. The results of assimilation of the hydrophysical survey data derived on the shelf in a telescopic model of the region are given.Translated by Mikhail M. Trufanov. 相似文献
998.
M. Taviani 《Geo-Marine Letters》1994,14(2-3):185-191
Recent suggestions that the Miocene-age calcari aLucina blocks scattered in the Apennine chain of the Italian peninsula are methanogenic in nature (paleo cold vents) calls for a reexamination of their macrofauna. Two Tortonian-age outcrops of such limestones (Case Rovereti and Montepetra) have been analyzed for their mollusk content and shown to host a diverse vent fauna. The paleoassemblages show remarkable similarities with modern counterparts associated with hydrocarbon venting on the Gulf of Mexico continental slope. Faunal data from both sites lend support to the hypothesis that methane/hydrocarbon venting was active during the Miocene and sustained specialized bathyal chemosynthetic communities in the ancient Mediterranean. 相似文献
999.
1000.
A hybrid thermal protection method using waste heat from a surface-mounted outboard motor is shown to create a warm “micro-climate” environment for divers. The effects of surface heater capacities, water flow rates, shelter volume and shelter insulation on micro-climate temperatures are characterized. During long, cold-water decompression stops this method offers a reliable, low-cost alternative to surface-supplied hot water suits or diver-carried heating systems. An added bonus for divers using closed-circuit breathing apparatus is prolonged durations of their carbon dioxide scrubbers when surrounded by the warm water “micro-climate”. Closed-circuit and open-circuit options of this diver decompression shelter concept are evaluated. 相似文献