Evolution of fumarolic gases — boundary conditions set by measured parameters: case study at Vulcano,Italy     

E. Mazor  R. Cioni  E. Corazza  M. Fratta  G. Magro  S. Matsuo  J. Hirabayashi  H. Shinohara  M. Martini  G. Piccardi  P. Cellini-Legittimo 《Bulletin of Volcanology》1988,50(2):71-85

Physical, chemical and isotopic parameters were measured in fumaroles at the Vulcano crater and in drowned fumaroles near the beach. The data were used to define boundary conditions for possible conceptual models of the system.Crater fumaroles: time variations of CO₂ and SO₂ concentrations indicate mixing of saline gas-rich water with local fresh water. Cl/Br ratios of 300– 400 favour sea-water as a major source for Cl, Brand part of the water in the fumaroles. Cl concentrations and D values revealed, independently, amixing of 0.75 sea-water with 0.25 local freshwaterin furmarole F-5 during September 1982.Patterns of parameter correlation and mass balances reveal that CO₂, S, NH₃ and B originate from sources other than sea water. The CO₂ value of ¹³C = – 2%_o favours, at least partial, origin from decomposition of sedimentary rocks rather than mantle-derived material. Radiogenic⁴He(1.3 × lO^–3 ccSTP/g water) and radiogenic⁴⁰Ar(10.6 × 10^–4 ccSTP/g water) are observed, (⁴He/⁴⁰Ar)_radiogenic = 1.2, well in the range of values observed in geothermal systems.Drowned fumaroles: strongly bubbling gas at a pond and at the beachappears to have the same origin and initial compositionas the crater fumaroles (2 km away). The fumarolic gas is modified by depletion of the reactive gases, caused by dissolution in shallow-water. Atmospheric Ne, Ar, Kr and Xe are addeden route, some radiogenic He and Ar are maintained. The Vulcano system seems to be strongly influenced by the contribution of sea-water and decomposition of sedimentary rocks. Evidence of magmatic contributions is mainly derived from heat.  相似文献   

A coronal condensation observed at the total solar eclipse of June 11, 1983 and a related transient prominence     

Yoshinori Suematsu  Sumisaburo Saito  Yasuhiro Funakoshi  Hiroki Kurokawa 《Solar physics》1988,116(2):285-290

A coronal condensation was observed simultaneously with Fexiv 5303, Fex 6374, Fe xi 7892, and H filtergraphs. The size and shape of the condensation in 5303 are different from those in other filtergrams. H filtergrams taken around the eclipse time show that a small transient prominence exists in close proximity to the condensation core and behaves like a post-flare loop system, though the appearance is quite different and no flare-report exists. A small-scale energetic phenomenon seems to have occurred at the top of magnetic loops.Contributions from the Kwasan and Hida Observatories, University of Kyoto, No. 285.  相似文献   

Effect of critical thinking disposition on household earthquake preparedness     

Yoshinori Nakagawa 《Natural Hazards》2016,81(2):807-828

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An initial response of magnetic fields at geosynchronous orbit to Pi 2 onset as observed from the dip-equator     

O. Saka  H. Akaki  O. Watanabe  M. Shinohara  D. N. Baker 《Annales Geophysicae》1998,16(5):542-548

Fluxgate magnetometer data recorded at the dip-equator (Huancayo, Peru; 1.44°N, 355.9° in geomagnetic coordinates; 12.1°S, 75.2°W in geographic coordinates; L = 1.00) with higher accuracy of timing (0.1 s) and amplitude resolution (0.01 nT) were utilized to survey an onset of Pi 2 pulsations in the midnight sector (2100–0100 LT) during PROMIS (Polar Region and Outer Magnetosphere International Study) periods (1 March–20 June, 1986). It is found that changing field line magnitude and vector as observed by magnetometer on board the synchronous satellites in the midnight sector often takes place simultaneously with the onset of Pi 2 pulsations at the dip-equator. The field disturbances that follow thereafter tend to last for some time both at the geosynchronous altitudes and the dip-equator. In this report, we examine the initial response of the field lines in space, and attempt to classify how the field line vector changed in the meridional plane.  相似文献   

Sessile animals on tar globules in the waters around the Ryukyu Islands     

Takeshi Kajihara  Yoshinori Ura  Miyako Tachibana 《Journal of Oceanography》1975,31(3):131-135

A large number of tar globules with sessile organisms were collected from the surface tows taken with larval nets in the waters around the Ryukyu Islands during November and December, 1973. Bryozoans (one species), tubeworms (Serpulidae,Janua (Dexiospira) foraminosa (Moore &Bush)) and goose barnacles (Lepas pectinata Spengler,L. anatifera Linné) were the most important species of sessile animals found on these tar globules. Sinking of tar globules byLepas of middle or large size was suggested from the differences in their specific gravity.  相似文献   

Why are spicules absent over plages and long under coronal holes?     

Kazunari Shibata  Yoshinori Suematsu 《Solar physics》1982,78(2):333-345

One-dimensional hydrodynamic simulations are performed in order to examine the influence of initial atmospheric structures on the dynamics of spicules. This is an extended version of our previous spicule theory: spicules are produced by the shock wave (MHD slow mode shock) which originates from a bright point appearance (sudden pressure increase) at the network in the photosphere or in the low chromosphere. Simulation results well reproduce the observational facts that spicules are absent over plages and long under coronal holes. The physical reason is that the growth of a shock wave during its propagation through the chromosphere is small in plage regions and large in coronal hole regions, since the growth of a shock is determined by the density ratio ( _{h 0}/ _c ) between the bright point and the corona. An empirical formula H _max ( _{h 0}/ _c )^0.46 is obtained, where H _max is the maximum height of spicules above the transition region. The cross-section of the vertical magnetic flux tube is assumed to be constant in the numerical simulations.  相似文献   

Throughfall partitioning by trees     

Delphis F. Levia  Kazuki Nanko  Hiromasa Amasaki  Thomas W. Giambelluca  Norifumi Hotta  Shin'ichi Iida  Ryan G. Mudd  Michael A. Nullet  Naoki Sakai  Yoshinori Shinohara  Xinchao Sun  Masakazu Suzuki  Nobuaki Tanaka  Chatchai Tantasirin  Kozo Yamada 《水文研究》2019,33(12):1698-1708

Although we know that rainfall interception (the rain caught, stored, and evaporated from aboveground vegetative surfaces and ground litter) is affected by rain and throughfall drop size, what was unknown until now is the relative proportion of each throughfall type (free throughfall, splash throughfall, canopy drip) beneath coniferous and broadleaved trees. Based on a multinational data set of >120 million throughfall drops, we found that the type, number, and volume of throughfall drops are different between coniferous and broadleaved tree species, leaf states, and timing within rain events. Compared with leafed broadleaved trees, conifers had a lower percentage of canopy drip (51% vs. 69% with respect to total throughfall volume) and slightly smaller diameter splash throughfall and canopy drip. Canopy drip from leafless broadleaved trees consisted of fewer and smaller diameter drops (D_{50_DR}, 50th cumulative drop volume percentile for canopy drip, of 2.24 mm) than leafed broadleaved trees (D_{50_DR} of 4.32 mm). Canopy drip was much larger in diameter under woody drip points (D_{50_DR} of 5.92 mm) than leafed broadleaved trees. Based on throughfall volume, the percentage of canopy drip was significantly different between conifers, leafed broadleaved trees, leafless broadleaved trees, and woody surface drip points (p ranged from <0.001 to 0.005). These findings are partly attributable to differences in canopy structure and plant surface characteristics between plant functional types and canopy state (leaf, leafless), among other factors. Hence, our results demonstrating the importance of drop‐size‐dependent partitioning between coniferous and broadleaved tree species could be useful to those requiring more detailed information on throughfall fluxes to the forest floor.  相似文献   

An experimental study on impact-induced alterations of planetary organic simulants          下载免费PDF全文

Yasuhito Sekine  Kenya Kodama  Takamichi Kobayashi  Seiji Obata  Yu Chang  Nanako O. Ogawa  Yoshinori Takano  Naohiko Ohkouchi  Koichiro Saiki  Toshimori Sekine 《Meteoritics & planetary science》2018,53(6):1267-1282

The present study systematically investigates shock-induced alteration of organic simulants of planetary bodies (OSPBs) as a function of peak shock pressure and temperature by impact experiments. Our results show that the composition and structure of OSPBs are unchanged upon impacts at peak pressures ≤~5 GPa and temperatures ≤~350 °C. On the other hand, these are dramatically changed upon impacts at >7–8 GPa and > ~400 °C, through loss of hydrogen-related bonds and concurrent carbonization, regardless of the initial compositions of OSPBs. Compared with previous results on static heating of organic matter, we suggest that shock-induced alteration cannot be distinguished from static heating only by Raman and infrared spectroscopy. Our experimental results would provide a proxy indicator for assessing degree of shock-induced alteration of organic matter contained in carbonaceous chondrites. We suggest that a remote-sensing signature of the 3.3–3.6 μm absorption due to hydrogen-related bonds on the surface of small bodies would be a promising indicator for the presence of less-thermally-altered (i.e., <350 °C) organic matter there, which will be a target for landing to collect primordial samples in sample-return spacecraft missions, such as Hayabusa2 and OSIRIS-REx.  相似文献   

Multi-decadal changes in the relationships between rainfall characteristics and debris-flow occurrences in response to gully evolution after the 1990–1995 Mount Unzen eruptions     

Haruka Tsunetaka  Yoshinori Shinohara  Norifumi Hotta  Christopher Gomez  Yuichi Sakai 《地球表面变化过程与地形》2021,46(11):2141-2162

Explosive volcanic eruptions can cause long-term landscape change, leading to increased sediment discharge that continues after the cessation of the eruptions. During the period 1990–1995, eruptions of Mount Unzen, Japan, generated large amounts of pyroclastic material, resulting in 57 debris-flow events during 1991–2018. To investigate changes in the relationships between rainfall characteristics and debris-flow occurrence, we conducted the following: geometric analysis of two gullies (i.e., debris-flow initiation zones) using LiDAR (light detection and ranging)-generated 1 m DEMs (digital elevation models); rainfall analysis, based on the relationship between rainfall duration and mean intensity (i.e., considering the intensity–duration, or ID, threshold); and debris-flow monitoring during 2016–2018. Since 1991, rainfall runoff has caused erosion of the supplied pyroclastic material, generating a channel network consisting of incised gullies. With sufficient rainfall, debris flows formed, accompanied by further gully erosion; this resulted in both vertical and lateral adjustments of the cross-sectional geometry. In the two decades since the eruptions ceased, readily mobilized pyroclastic material has become scarce as the gullies have adjusted to local hydrographic conditions. At the same time, the infiltration capacity of the volcanic flank has increased, reducing the capacity for overland flow. As a result, since 2000, rainfall events with intensities above the ID threshold have occurred; however, the lack of sediment supplied by the gullies appears to have hindered the occurrence and development of debris flows. This suggests that debris flows in volcanically perturbed landscapes may occur at lower rainfall thresholds as long as the corresponding upland channels are evolving as a result of intense overland flow. However, as such channels evolve towards equilibrium geometries, the frequency of debris flows decreases in response to the reduction in sediment availability.  相似文献   

Petrological characteristics and volatile content of magma from the 2000 eruption of Miyakejima Volcano, Japan     

Genji Saito  Kozo Uto  Kohei Kazahaya  Hiroshi Shinohara  Yoshihisa Kawanabe  Hisao Satoh 《Bulletin of Volcanology》2005,67(7):691-693

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