Relation Between Coronal Hole Areas and Solar Wind Speeds Derived from Interplanetary Scintillation Measurements     

Munetoshi Tokumaru  Daiki Satonaka  Ken’ichi Fujiki  Keiji Hayashi  Kazuyuki Hakamada 《Solar physics》2017,292(3):41

We investigate the relation between coronal hole (CH) areas and solar wind speeds during 1995?–?2011 using the potential field (PF) model analysis of magnetograph observations and interplanetary scintillation (IPS) observations by the Institute for Space-Earth Environmental Research (formerly Solar-Terrestrial Environment Laboratory) of Nagoya University. We obtained a significant positive correlation between the CH areas (\(A\)) derived from the PF model calculations and solar wind speeds (\(V\)) derived from the IPS observations. The correlation coefficients between them are usually high, but they drop significantly in solar maxima. The slopes of the \(A\)?–?\(V\) relation are roughly constant except for the period around solar maximum, when flatter or steeper slopes are observed. The excursion of the correlation coefficients and slopes at solar maxima is ascribed partly to the effect of rapid structural changes in the coronal magnetic field and solar wind, and partly to the predominance of small CHs. It is also demonstrated that \(V\) is inversely related to the flux expansion factor (\(f\)) and that \(f\) is closely related to \(A^{-1/2}\); hence, \(V \propto A^{1/2}\). A better correlation coefficient is obtained from the \(A^{1/2}\)?–?\(V\) relation, and this fact is useful for improving space weather predictions. We compare the CH areas derived from the PF model calculations with He i 1083 nm observations and show that the PF model calculations provide reliable estimates of the CH area, particularly for large \(A\).  相似文献   

Fragmentation of star-forming clouds enriched with the first dust     

Raffaella Schneider  Kazuyuki Omukai  Akio K. Inoue  Andrea Ferrara 《Monthly notices of the Royal Astronomical Society》2006,369(3):1437-1444

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Surface heat balance and pan evaporation trends in Eastern Asia in the period 1971–2000     

Jianqing Xu  Shigenori Haginoya  Kazuyuki Saito  Ken Motoya 《水文研究》2005,19(11):2161-2186

Climatic variations over Eastern Asia, including the Tibetan Plateau, were analysed using meteorological data for 32 points in the period 1971 to 2000. Changes in heat and water balances were examined using potential evaporation E_P, and a wetness index WI, as suggested by Kondo and Xu ( 1997a,b ). Climate zones, including the humid, semi‐humid, semi‐arid and arid climate types, in Eastern Asia identified by the wetness index matched the vegetation distribution. Average monthly temperatures increased over the 30 years, with the sharpest increase in February. In general, temperature increases were larger in the north than in the south. Air temperature increased by more than 0·05 K yr⁻¹ in northern China. The data showed that diurnal temperature ranges have decreased in recent years. From the Tibetan Plateau, through central China, to southern northeast China, there has been an increase in potential evaporation and pan evaporation, which may be related to both higher temperatures and a lack of surface water. Increasing long‐wave radiation flux is apparent in every month and in the interannual trends. This is in contrast to the solar radiation flux. On the other hand, trends for relative humidity and cloud cover were negative, but positive for water vapour pressure. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   

Accurate ocean tide modeling in southeast Alaska and large tidal dissipation around Glacier Bay     

Daisuke Inazu  Tadahiro Sato  Satoshi Miura  Yusaku Ohta  Kazuyuki Nakamura  Hiromi Fujimoto  Christopher F. Larsen  Tomoyuki Higuchi 《Journal of Oceanography》2009,65(3):335-347

An accurate prediction of ocean tides in southeast Alaska is developed using a regional, barotropic ocean model with a finite difference scheme. The model skill is verified by the observational tidal harmonics in southeast Alaska including Glacier Bay. The result is particularly improved in Glacier Bay compared to the previous model described by Foreman et al. (2000). The model bathymetry dominates the model skill. We re-estimate tidal energy dissipation in the Alaska Panhandle and suggest a value for tidal energy dissipation of 3.4 GW associated with the M₂ constituent which is 1.5 times the estimation of Foreman et al. (2000). A large portion of the M₂ energy budget entering through Chatham Strait is dissipated in the vicinity of Glacier Bay. Moreover, it is shown that the developed model has the potential to correct the ocean tide loading effect in geodetic data more efficiently than the model of Foreman et al. (2000), especially around Glacier Bay.  相似文献   

Solar Wind Speed and Expansion Rate of the Coronal Magnetic Field during Carrington Rotation 1909     

Hakamada  Kazuyuki  Kojima  Masayoshi 《Solar physics》1999,187(1):115-122

The synoptic map of the solar wind speed (SWS) estimated by the computer-assisted tomography (CAT) method with interplanetary scintillation observations is constructed for the 1909 Carrington rotation. A similar synoptic map of expansion rate (RBR) of the coronal magnetic field calculated by the so-called 'potential model' with the photospheric magnetic field is also constructed under the radial field assumption (RF model). These maps consist of 64800 (180×360) data points of equal area. We examine for the first time relations between the SWS estimated by the CAT technique and the RBR calculated by the RF model. A highly significant correlation is found between the SWS and the RBR. A simple correlation coefficient is about –0.72; that is, high-velocity winds emanate from photospheric areas corresponding to a low expansion rate of the coronal magnetic field, and low-velocity winds emanate from photospheric areas of high expansion rate. This result suggests that there is some acceleration mechanism relating to the coronal field expansion.  相似文献   

Formation Process of North Pacific Intermediate Water Revealed by Profiling Floats Set to Drift on 26.7 σθ Isopycnal Surface     

Yugo Shimizu  Takanori Iwao  Ichiro Yasuda  Shin-Ichi Ito  Tomowo Watanabe  Kazuyuki Uehara  Nobuyuki Shikama  Toshiya Nakano 《Journal of Oceanography》2004,60(2):453-462

Six newly developed floats, which were set to drift on the 26.7 σ_θ isopycnal surface and to profile temperature, salinity and pressure above 1000 dbar once a week, were deployed in the Oyashio and Kuroshio Extension (KE) in order to examine the circulation, formation site and time scale of newly formed North Pacific Intermediate Water (NPIW). The floats were deployed in February or May 2001, and the data from their deployments to December 2002 are analyzed here. Four of the six floats were deployed near the KE axis at around the first meander crest, and they moved eastward to 157°E–176°W at latitudes of 30°N–45°N. The other two floats deployed in the Oyashio water with low-potential vorticity near the south coast of Hokkaido moved southward to reach the KE front and then moved eastward to the same region as the first four floats. The temperature and salinity at 26.7 σ_θ measured by the profiling floats indicate that the source waters of NPIW, Oyashio and Kuroshio waters are drastically mixed and modified in the mixed water region west of 160°E. The floats were separated into the three paths east of 160°E between the Kuroshio Extension front and the north of Water-Mass front (nearly subarctic front). New NPIW is judged to be formed along these three paths since the vertical profiles of temperature and salinity are quite smooth, having a salinity minimum at about 26.7σ_θ along each path. Kuroshio-Oyashio isopycnal mixing ratios of the new NPIW are 7:3, 6:4 and 5:5 at 26.7σ_θ along the southern, middle and northern paths, respectively. Potential vorticity converges to about 14–15 × 10⁻¹¹ m⁻¹s⁻¹ along these paths. The time scale of new NPIW formation is estimated to be 1–1.5 years from the merger of Oyashio and Kuroshio waters to the formation of the new NPIW. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Enzymatic Approach to Fungal Association with Arthropod Guts: A Case Study for the Crustacean Host, Nihonotrypaea harmandi, and Its Foregut Fungus, Enteromyces callianassae     

Hiroshi Kimura  Kazuyuki Harada  Kenji Hara  & Akio Tamaki 《Marine Ecology》2002,23(2):157-183

Abstract. In the callianassid shrimp Nihonotrypaea harmandi (Bouvier 1901), the trichomycete fungus Enteromyces callianassae Lichtwardt 1961 occurs exclusively on the foregut lining. The enzymes from both the shrimp and the fungus apparently hydrolyze certain nitrogen and carbon compounds in detritus. The activities of various proteases and carbohydrases contained in the foregut juice were compared between fungus-infected shrimps collected from a sandflat in Kyushu, Japan (51 % infection rate) and uninfected shrimps from a nearby sandflat. The concentration of enzymatically hydrolyzable amino acids (EHAA) in sediment liberated by the foregut juice with fungi was slightly lower than that by 0.1 mg·ml^-1 proteinase-K and significantly higher than that by the foregut juice without fungi. In both foregut juices, substantial enzyme activities were recorded for proteinase(s), peptidases, amylase, cellulase and β-1,3-glucanase, and minimal ones for maltase and cellobiase. Of the commercial substrates examined, only in the case of the mixture of 16 kinds of dipeptides was a significantly higher enzyme activity in the foregut juice with fungi observed. In the process of EHAA liberation from sediment, peptidases secreted by the fungus most probably act as a supplement to the endogenous secretion by the shrimp. This may explain the higher shrimp growth rate recorded for the population with fungi. However, the significantly higher sediment EHAA concentration of the sandflat inhabited by this population versus the population without fungi could be another crucial factor explaining the site difference in shrimp growth rate.  相似文献   

Characteristics of the Kuroshio in the vicinity of the Izu Ridge     

Kazuyuki Otsuka 《Journal of Oceanography》1985,41(6):441-451

Characteristics of the Kuroshio in the vicinity of the Izu Islands are analyzed by using hydrographic observations collected from 1938 to 1980 mostly by the Hydrographic Department, Maritime Safety Agency, Japan and by the Japan Meteorological Agency.It is shown that flow characteristics change as the Kuroshio approaches the Izu Ridge. 1) The position of the 10°C isotherm at the 500 m level, which is, an index of the position of the temperature front or of the current axis of the Kuroshio, is highly variable near the ridge. 2) The horizontal temperature gradient across the Kuroshio estimated from the positions of the 8 and 12°C isotherms across the Kuroshio decreases considerably near the Izu Ridge. 3) The horizontal distance between the 15°C isotherm at the 200 m level and 10°C isotherm at the 500 m level becomes larger over the ridge. The 15°C isotherm at the 200 m level is an index of the current axis at the sea surface. This implies that the inclination of the Kuroshio axis becomes larger over the ridge.  相似文献   

Age of the Taishu Group,southwestern Japan,and implications for the origin and evolution of the Japan Sea     

Takashi Ninomiya  Shoichi Shimoyama  Koichiro Watanabe  Kenji Horie  Daniel J. Dunkley  Kazuyuki Shiraishi 《Island Arc》2014,23(3):206-220

The Taishu Group, a marine formation with a thickness of >5400 m, crops out on Tsushima Island, located in the southwestern Japan Sea. The group, which is generally regarded as early Eocene to early Miocene in age, provides important information about the tectonic setting of the Japan Sea. In this study, we present new SHRIMP U–Pb dates for igneous zircons from the Kunehama Tuff, which is in the basal part of the Taishu Group, and the Oobaura Tuff, which is in the uppermost part of the group. Results show that the Taishu Group was deposited rapidly, during the short interval of 17.9–15.9 Ma (early–middle Miocene), and is equivalent to other early–middle Miocene strata found in the Japan Sea region. Our results provide new constraints on the geological history of the Japan Sea and its islands.  相似文献   

Redistribution and export of contaminated sediment within eastern Fukushima Prefecture due to typhoon flooding          下载免费PDF全文

Akihiro Kitamura  Hiroshi Kurikami  Kazuyuki Sakuma  Alex Malins  Masahiko Okumura  Masahiko Machida  Koji Mori  Kazuhiro Tada  Yasuhiro Tawara  Takamaru Kobayashi  Takafumi Yoshida  Hiroyuki Tosaka 《地球表面变化过程与地形》2016,41(12):1708-1726

Tropical cyclones expose river basins to heavy rainfall and flooding, and cause substantial soil erosion and sediment transport. There is heightened interest in the effects of typhoon floods on river basins in northeast Japan, as the migration of radiocaesium‐bearing soils contaminated by the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident will affect future radiation levels. The five main catchments surrounding FDNPP are the Odaka, Ukedo, Maeda, Kuma and Tomioka basins, but little quantitative modelling has been undertaken to identify the sediment redistribution patterns and controlling processes across these basins. Here we address this issue and report catchment‐scale modelling of the five basins using the GETFLOWS simulation code. The three‐dimensional (3D) models of the basins incorporated details of the geology, soil type, land cover, and used data from meteorological records as inputs. The simulation results were checked against field monitoring data for water flow rates, suspended sediment concentrations and accumulated sediment erosion and deposition. The results show that the majority of annual sediment migration in the basins occurs over storm periods, thus making typhoons the main vectors for redistribution. The Ukedo and Tomioka basins are the most important basins in the region in terms of overall sediment transport, followed by the other three basins each with similar discharge amounts. Erosion is strongly correlated with the underlying geology and the surface topography in the study area. A low permeability Pliocene Dainenji formation in the coastal area causes high surface water flow rates and soil erosion. Conversely, erosion is lower in an area with high permeability granite basement rocks between the Hatagawa and Futaba faults in the centre of the study area. Land cover is also a factor controlling differences in erosion and transport rates between forested areas in the west of the study area and predominantly agricultural areas towards the east. The largest sediment depositions occur in the Ogaki and Takigawa Dams, at the confluence of the Takase and Ukedo Rivers, and at the Ukedo River mouth. Having clarified the sediment redistribution patterns and controlling processes, these results can assist the ongoing task of monitoring radioactive caesium redistribution within Fukushima Prefecture, and contribute to the design and implementation of measures to protect health and the environment. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献