Estimation of field irrigation water demand based on lumped kinematic wave model considering soil moisture balance

An estimation model of farm field irrigation water demand is developed. The model is based on the lumped kinematic wave model considering soil water balance. The lumped model approach reduces the computational load in rainfall-runoff analysis and allows application to large river basins. Evapotranspiration is estimated on hourly basis by the improvement of FAO’s method. Not only water volume necessary for farm field irrigation but also the number of the water charge and its interval can be estimated by the combined use of the lumped runoff model and the hourly evapotranspiration model.     

Gamma-Ray Bursts and magnetar-forming Supernovae

The connection between long Gamma Ray Bursts (GRBs) and Supernovae (SNe) have been established through the well observed cases. These events can be explained as the prompt collapse to a black hole (BH) of the core of a massive star (M≳40M _⊙). The energies of these GRB-SNe were much larger than those of typical SNe, thus these SNe are called Hypernovae (HNe). The case of SN 2006aj/GRB060218 appears different: the GRB was weak and soft, being called an X-Ray Flash (XRF); the SN is dimmer and has very weak oxygen lines. The explosion energy of SN 2006aj was smaller, as was the ejected mass. In our model, the progenitor star had a smaller mass than other GRB-SNe (M∼20M _⊙), suggesting that a neutron star (NS) rather than a BH was formed. If the nascent NS was strongly magnetized as a magnetar and rapidly spinning, it may launch a weak GRB or an XRF. The peculiar light curve of Type Ib SN 2005bf may also be powered by a magnetar. The blue-shifted nebular emission lines of 2005bf indicate the unipolar explosion possibly related to standing accretion shock instability (SASI) associated with a newly born NS.     

Sequentially sampled gas hydrate water,coupled with pore water and bottom water isotopic and ionic signatures at the Kukuy mud volcano,Lake Baikal: ambiguous deep-rooted source of hydrate-forming water

The isotopic and ionic composition of pure gas hydrate (GH) water was examined for GHs recovered in three gravity cores (165–193 cm length) from the Kukuy K-9 mud volcano (MV) in Lake Baikal. A massive GH sample from core St6GC4 (143–165 cm core depth interval) was dissociated progressively over 6 h in a closed glass chamber, and 11 sequentially collected fractions of dissociated GH water analyzed. Their hydrogen and oxygen isotopic compositions, and the concentrations of Cl^– and HCO₃ ^– remained essentially constant over time, except that the fraction collected during the first 50 minutes deviated partly from this pattern. Fraction #1 had a substantially higher Cl^– concentration, similar to that of pore water sampled immediately above (135–142 cm core depth) the main GH-bearing interval in that core. Like the subsequent fractions, however, the HCO₃ ^– concentration was markedly lower than that of pore water. For the GH water fractions #2 to #11, an essentially constant HCO₃ ^–/Cl^– ratio of 305 differed markedly from downcore pore water HCO₃ ^–/Cl^– ratios of 63–99. Evidently, contamination of the extracted GH water by ambient pore water probably adhered to the massive GH sample was satisfactorily restricted to the initial phase of GH dissociation. The hydrogen and oxygen isotopic composition of hydrate-forming water was estimated using the measured isotopic composition of extracted GH water combined with known isotopic fractionation factors between GH and GH-forming water. Estimated δD of ?126 to ?133‰ and δ¹⁸O of ?15.7 to ?16.7‰ differed partly from the corresponding signatures of ambient pore water (δD of ?123‰, δ¹⁸O of ?15.6‰) and of lake bottom water (δD of ?121‰, δ¹⁸O of ?15.8‰) at the St6GC4 coring site, suggesting that the GH was not formed from those waters. Observations of breccias in that core point to a possible deep-rooted water source, consistent with published thermal measurements for the neighboring Kukuy K-2 MV. By contrast, the pore waters of core St6GC4 and also of the neighboring cores GC2 and GC3 from the Kukuy K-9 MV show neither isotopic nor ionic evidence of such a source (e.g., elevated sulfate concentration). These findings constrain GH formation to earlier times, but a deep-rooted source of hydrate-forming water remains ambiguous. A possible long-term dampening of key deep-water source signatures deserves further attention, notably in terms of diffusion and/or advection, as well as anaerobic oxidation of methane.     

Deep current structure in the Toyama Deep-Sea Channel in the Japan Sea

Journal of Oceanography - The flow field in the Toyama Deep-Sea Channel (TDSC) in the Japan Sea was investigated based on mooring observations. An asymmetric current system accompanying offshore...     

Sudden strong current generated by an eddy in the eastern part of Wakasa Bay,Japan

A sudden strong coastal current called a “kyucho” occurred in August 2013 in the eastern coastal waters of Wakasa Bay, Japan. This study examined its characteristics based on both observational data collected by intensive field investigations and the simulation results of a numerical model. The field investigations comprised moored buoy observations near the coast and voyages by a research vessels and fishing boats. The mooring observations indicated that a current speed exceeding 50 cm s^?1 occurred abruptly near the eastern coast of the bay, in association with a synchronous change in the current direction. Data collected by acoustic Doppler current profilers (ACDPs) mounted on the vessels showed that a clockwise eddy existed in the bay and that the current on the east side of the eddy generated the kyucho near the coast. Based on the results of the numerical model and the analysis of the ADCP data, it was considered that the clockwise eddy was generated by a strong current at the tip of the Tango Peninsula, in the western part of the bay. As the eddy propagated from west to east across the bay, it induced the kyucho in the coastal waters in the east of the bay.     

Experimental calibration of sapphirine–spinel Fe–Mg exchange thermometer: Implication for constraints on P–T condition of Howard Hills, Napier Complex, East Antarctica

The Fe²⁺–Mg distribution coefficients between sapphirine and spinel:

were experimentally determined at pressures of 9–13 kbar and temperatures of 950–1150 °C using a natural ultrahigh-temperature (UHT) granulite with paragenesis of these minerals from the Napier Complex in East Antarctica [X_Mg = Mg / (Fe + Mg); X_Fe = Fe / (Fe + Mg)]. A new sapphirine–spinel geothermometer has been obtained as:

We applied the exchange thermometer to UHT or high-grade metamorphic rocks that were reported from various complexes in the world. If the K_D values of 2.63–4.34 obtained from low-Cr mineral pairs such as X_Cr^Spr < 0.016 and X_Cr^Spl < 0.047 were substituted into the equation, their temperature conditions would be estimated as 806–1050 °C at 11 kbar. The X_Cr means Cr / (Al + Cr(+ Fe³⁺)). These temperatures are reasonable retrograde or near peak metamorphic condition.     

A Long-Lived Center of Gas–Fluid Emanations on the Western Slope of the Kuril Basin (Sea of Okhotsk)

Lithology and Mineral Resources - The paper presents the results of multidisciplinary studies in the carbonate–barite mineralization area revealed on the western slope of the Kuril deep-water...     

Interannual and Decadal Sea-Level Variations along the Japanese Coast

Interannual (an annual to a decadal) and decadal sea-level variations along the Japanese coast have been investigated on the basis of monthly mean sea level during the period from 1951 to 1995. For the interannual variation, the Japanese coast is divided into six regions according to a regional similarity of sea level by using the cluster analysis, which is close to Tsumura's (1963) classification. The first mode of the Empirical Orthogonal Function (EOF) of the Interannual variation is the simultaneous rising and falling of the sea level along the Japanese coast. The first mode shows the largest variation in winter and has a negative correlation with the wintertime monsoon index; this suggests that the first mode is associated with a steric height change depending on the wintertime cooling intensity. The EOF second mode represents the Kuroshio large meander because strong negative eigenvectors are seen on the southeast coast of Japan and the time coefficient shows a high correlation with the Kushimoto-Uragami sea-level difference. For the decadal sea-level variation, the EOF first mode is a bi-decadal variation exhibiting simultaneous rising and falling of the sea level for the entire Japanese coast. The time coefficient of the first mode shows the first minimum in 1965, reaches a maximum in 1975, and decreases to the second minimum in 1984. The decrease from the mid-1970s and the increase from the mid-1980s to early 1990s correspond to the climatic regime shifts occurring in the same periods.