Interannual and synoptic-scale features of two types of cold-air outbreaks over the East China Sea during 1988�C2006     

Kae Kuriyama  Masaru Yamamoto 《Theoretical and Applied Climatology》2011,103(3-4):291-304

For the 1988?C2006 cold seasons, we investigated the characteristic structures of two types of cold-air outbreaks over the East China Sea: Type N, for which a thick layer of northerly meridional wind was formed during the cold-air outbreak; and Type S, for which an initially thin layer of northerly meridional wind was gradually thickened as the cold-air outbreak developed. The emergence frequencies of Type N and Type S outbreaks are sensitive to winter monsoon intensity at the 500-hectopascal (hPa) level. Type S outbreaks are dominant during strong El Ni?o events, leading to enhanced southerly meridional flow at 500?hPa over the East China Sea. The development of the 500-hPa Pacific High strongly influences the synoptic-scale structures of the two different types of outbreaks over the East China Sea.  相似文献   

Year-round accumulation of particulate organic matter in the estuarine turbidity maximum: comparative observations in three macrotidal estuaries (Chikugo, Midori, and Kuma Rivers), southwestern Japan   总被引：1，自引：1，他引：0  

Keita W. Suzuki  Akihide Kasai  Kouji Nakayama  Masaru Tanaka 《Journal of Oceanography》2012,68(3):453-471

The inner part of the Ariake Sea is one of the most productive estuarine systems in Japan. To examine potential food items for estuarine organisms, we conducted monthly observations of the dynamics of particulate organic matter along the macrotidal Chikugo River estuary in 2005 and 2006. In the neighboring macrotidal Midori and Kuma River estuaries, comparative observations were made. High turbidity and strong vertical mixing were observed only at low salinities (<10) in the Chikugo River estuary. In contrast, the Midori and Kuma River estuaries were characterized by less turbid and less mixed waters. Concentrations of particulate organic carbon often exceeded 5?mg?l^?1 in or close to the estuarine turbidity maximum (ETM) of the Chikugo River estuary. However, such high concentrations were rarely observed in the other two estuaries. The observed differences could be attributable to different hydrodynamic processes related to the different lengths of tidal reaches: 23, 8, and 6?km in the Chikugo, Midori, and Kuma Rivers, respectively. In the Chikugo River estuary, spatiotemporal changes of chlorophyll a suggested that phytoplankton occurred abundantly up- and/or downstream from the ETM especially during the warm season. In contrast, pheophytin (i.e., plant detritus) always accumulated in or close to the ETM. Carbon stable isotope ratios and carbon to nitrogen ratios indicated that the plant detritus was derived from phytoplankton and terrestrial plants. The Chikugo River estuary has a high potential to support the production of estuarine organisms through abundant plant detritus in the well-developed ETM all the year round.  相似文献   

Mesoscale structures of two types of cold-air outbreaks over the East China Sea and the effect of coastal sea surface temperature     

Masaru Yamamoto 《Meteorology and Atmospheric Physics》2012,115(3-4):89-112

Two types of cold-air outbreaks over the Yellow and East China Seas are investigated using a regional mesoscale model. Distinct patterns of surface turbulent heat fluxes and precipitation are identified between the two cases. The sea surface heat flux and frictional velocity are strongly influenced by mesoscale differences between high- and low-resolution datasets of sea surface temperature (SST). The influence of the SST difference on atmospheric water is spread to the downstream area of the outbreak with the phase transition of water. The air mass transformation around 800?hPa over the Kuroshio is partly influenced by the upstream SST difference. In particular, the SST difference near the mouth of the Yanzi River strongly modifies the air mass around Taiwan. Thus, in addition to the Kuroshio front, the mesoscale Chinese coastal SST structure is also important in the air mass transformation over the East China Sea.  相似文献   

Biogeochemical simulation of microbially induced calcite precipitation with Pararhodobacter sp. strain SO1     

Akiyama  Masaru  Kawasaki  Satoru 《Acta Geotechnica》2019,14(3):685-696

Acta Geotechnica - Biogrouting is a ground improvement technique, which utilizes microorganisms. The numerical simulation of biogrouting is important to ensure efficient operation and to assess the...  相似文献   

Thematic Section: Fluid-rock interaction in the bottom of the inland seismogenic zone
Preface     

Masaru  Terabayashi  Kazuaki  Okamoto  Hiroshi  Yamamoto  Yu-Chang  Chan 《Island Arc》2010,19(1):1-3

  相似文献   

Source process of very-long-period events accompanying long-period signals at Cotopaxi Volcano,Ecuador     

Indira Molina  Hiroyuki Kumagai  Alexander García-Aristizábal  Masaru Nakano  Patricia Mothes 《Journal of Volcanology and Geothermal Research》2008

Renewed seismic activity of Cotopaxi, Ecuador, began in January 2001 with the increased number of long-period (LP) events, followed by a swarm of volcano-tectonic (VT) earthquakes in November 2001. In late June 2002, the activity of very-long-period (VLP) (2 s) events accompanying LP (0.5–1 s) signals began beneath the volcano. The VLP waveform was characterized by an impulsive signature, which was accompanied by the LP signal showing non-harmonic oscillations. We observed temporal changes of both the VLP and LP signals from the beginning until September 2003: The VLP signal gradually disappeared and the LP signal characterized by decaying harmonic oscillations became dominant. Assuming possible source geometries, we applied a waveform inversion method to the observed waveforms of the largest VLP event. Our inversion and particle motion analyses point to volumetric changes of a sub-vertical crack as the VLP source, which is located at a depth of 2–3 km beneath the northeastern flank. The spectral analysis of the decaying harmonic oscillations of LP events shows frequencies between 2.0 and 3.5 Hz, with quality factors significantly above 100. The increased VT activity and deformation data suggest an intrusion of magma beneath the volcano. A release of gases with small magma particles may have repetitively occurred due to the pressurization, which was caused by sustained bubble growth at the magma ceiling. The released particle-laden gases opened a crack above the magma system and triggered the resonance of the crack. We interpret the VLP and LP events as the gas-release process and the resonance of the crack, respectively.  相似文献   

次固结沉降对压缩时间曲线的影响研究   总被引：5，自引：2，他引：3  

廖红建  苏立君  白子博明  赤石胜 《岩土力学》2002,23(5):536-540

提出了一种新的考虑次固结影响的一维固结方程,并用于计算粘土的压缩时间关系曲线。通过试验结果和计算分析验证了该方程的合理性。为了考察不同最大排水距离和加载时间间隔对固结过程的影响,对重塑正常固结粘土进行了一系列固结试验,研究了次固结对固结系数和压缩量的影响;将试验结果与解析方法的预测结果进行了比较。可为软土路基和填土路基的沉降问题提供设计参考。  相似文献   

The geochemistry of lead in rivers,estuaries and the continental shelf of the Southeastern United States     

Herbert L Windom  Ralph G Smith  Masaru Maeda 《Marine Chemistry》1985,17(1):43-56

Transport by southeastern rivers has insignificant influence on the lead concentration of southeastern shelf waters. If the rate of mobilization and transport of lead by these rivers is representative of uncontaminated fluvial transport during the Pleistocene, only about 5% of the prehistoric output of lead to the North Atlantic can be accounted for by river input.Lead concentrations in southeastern shelf waters are similar to those of North Atlantic Water from the upper 1000 m, which is probably similar to the intrusion source water for the shelf. Atmospheric inputs to the shelf of the same magnitude as observed for the Western North Atlantic are difficult to reconcile given the residence time of shelf waters and their lead concentration unless the rate of loss of lead to shelf sediments is about the same as the atmospheric flux.  相似文献   

Coastal aquifer system in late Pleistocene to Holocene deposits at Horonobe in Hokkaido,Japan   总被引：1，自引：0，他引：1  

Reo Ikawa  Isao Machida  Masaru Koshigai  Seiji Nishizaki  Atsunao Marui 《Hydrogeology Journal》2014,22(5):987-1002

The groundwater flow systems and chemistry in the deep part of the coastal area of Japan have attracted attention over recent decades due to government projects such as geological disposal of radioactive waste. However, the continuous groundwater flow system moving from the shallow to deep parts of the sedimentary soft rock has not yet been characterized. Therefore, the Cl^–, δD and δ¹⁸O values of the pore water in the Horonobe coastal area in Hokkaido, Japan, were measured to 1,000 m below the ground surface, and a vertical profile of the pore-water chemistry was constructed to assist in elucidating groundwater circulation patterns in the coastal area. The results show that the groundwater flow regime may be divided into five categories based on groundwater age and origin: (1) fresh groundwater recharged by modern rainwater, (2) fresh groundwater recharged by paleo rainwater during the last glacial age, (3) low-salinity groundwater recharged during the last interglacial period, (4) mixed water in a diffusion zone, and (5) connate water consisting of paleo seawater. These results suggest that the appearance of hydrological units is not controlled by the boundaries of geological formations and that paleo seawater is stored in younger Quaternary sediments.  相似文献   

Fast Oxidation Reaction of Nitrite by Dissolved Oxygen in the Freezing Process in the Tropospheric Aqueous Phase     

Norimichi Takenaka  Tohru Daimon  Akihiro Ueda  Keiichi Sato  Masaru Kitano  Hiroshi Bandow  Yasuaki Maeda 《Journal of Atmospheric Chemistry》1998,29(2):135-150

Nitrite oxidation in the tropospheric aqueous phase by freezing was evaluated by freezing a field sample. Nitrite oxidation by dissolved oxygen in the freezing process is much faster than by other oxidation processes, such as reactions with ozone, hydrogen peroxide or dissolved oxygen in an aqueous solution at pHs 3 to –6. At pH 4.5 and 25°C, the lifetime of nitrite in the aqueous phase is ca. 1 hr in oxidation by ozone (6×10^-10 mol dm^-3), ca. 10 hr in oxidation by H₂O₂ (2×10^-4 mol dm^-3), and 7.5 hr (Fischer and Warneck, 1996) in photodissociation at midday in summer. Under the same conditions at a temperature below 0°C, the lifetime of nitrite in the freezing process is estimated as ca. 2 sec when the droplets are frozen within a second. The reaction by freezing is affected by the presence of salts, such as NaCl or KCl, or orgnaic compounds, such as methanol or acetone. The results of freezing a field rain or fog sample showed that nitrite oxidation proceeds below pH 6, and the conversion ratio of nitrate from nitrite increases with decreasing pH. The oxidation of nitrite by freezing was also observed in freezing fog particles generated by an ultrasonic humidifier. The ratios of the concentrations of ions in the winter sample to those in the summer sample (or those in the fog sample) were almost the same values. However, the concentration of nitrite in the winter sample was lower than that estimated by the ratios of other ions. From the present study, it seems that the freezing process plays an important role in the nitrite sink process in the tropospheric aqueous phase.  相似文献