A new model for predicting three-dimensional beach changes by expanding Hsu and Evans' equation

The empirical bay shape model proposed by Hsu and Evans in 1989 for predicting the static planform of a pocket beach is expanded to enable the calculation of three-dimensional beach changes on a pocket beach with a seawall. The original formulation was developed on the basis of a second-order regression analysis. Unlike the one-line model of shoreline changes, the model of Hsu and Evans does not require repeated calculations of the wave field and shoreline position, because it was derived on the assumption of null sediment movement within a pocket beach in static equilibrium, hence without the need of applying the continuity condition of total sand volume in the calculation. The expanded model proposed by the present authors satisfies the total sand budget on a pocket beach, by taking into account the concept of depth change due to longshore sand transport. Model tests were carried out and the new model was further applied to the beach changes at Kemigawa on the northeast of Tokyo Bay in Chiba Prefecture, as well as at Oarai in Ibaraki Prefecture, Japan. On both locations, seawall has been installed as countermeasures against beach erosion, where wave sheltering effect of the main breakwater and beach changes in front of the seawall has also been observed. With this expansion, the present model can be applied to predict the three-dimensional beach changes on a coast with seawall on a pocket beach.     

A large arcade along the inversion line,observed on May 19, 1992 by Yohkoh,and enhancement of interplanetary energetic particles

A large arcade associated with a long-duration soft X-ray emission was observed on May 19, 1992 by the Yohkoh soft X-ray telescope. This large arcade was formed along the inversion line and a filament eruption was observed as part of this event. Also associated with this event were solar energetic particles and an interplanetary shock observed near Earth. This event supports the idea that coronal mass ejections are large-scale eruptions along an inversion line, or a heliospheric current sheet. However, this event implies that present models on eruptions are not sufficient.     

Experimental degradation of crude oil by marine bacteria

The ability of biodegradation for crude oil was examined for ten strains of marine bacteria. With regard to their degradation ability forn-alkanes the microorganisms tested could be divided into four groups, although the same result was not observed for microbial degradation of aromatic hydrocarbons obtained by the UV measurements.     

A hybrid approach for deriving horizontal site amplification factors considering both the similarity of HVSRE and the vertical amplification correction function

Under hypothetical and idealized conditions, the horizontal site amplification factor (HSAF) is defined as the ratio of the horizontal Fourier amplitude spectrum (FAS) at a point on the Earth's surface with respect to the horizontal FAS at the identical location but on the outcropping seismological bedrock. The HSAF reflects the profile of local sedimentary soils and weathered rock formations, indicating site effects. In most cases, such an idealized HSAF is difficult to measure directly. Thus, quantitatively estimating a HSAF value is a crucial task in strong-motion prediction over the last century. Fortunately, many strong-motion stations have been constructed throughout Japan, facilitating the characterization of HSAFs down to seismological bedrock at more than 1600 observational sites by the generalized inversion technique (GIT). First, this study reported the similarity distribution of the HSAF and the horizontal-to-vertical spectral ratio of earthquakes (HVSR_E). Subsequently, we proposed a hybrid method from a novel aspect for estimating HSAF in terms of the observed similarity distribution and the vertical amplification correction function (VACF) proposed previously. Compared with the direct use of HVSR_E for substituting HSAF, the hybrid method proposed herein demonstrated an improvement of greater than 30% in terms of the residuals between estimated HSAFs and those separated from observations.     

Separation of periodic, chaotic, and random components in solar activity

Two new techniques were applied to search for chaotic behavior in solar activity. A mixture of periodic and chaotic components in a time series makes it difficult to find chaotic behavior. The singular spectrum analysis (SSA) method (Broomhead and King, 1986) was used to separate periodic and irregular components in solar activity (e.g., sunspot number and 10.7 cm flux). The nonlinear prediction method (Sugihara and May, 1990) was applied for each component to examine whether it has a chaotic characteristic. The result suggests that are are dominant periodic components and highly irregular (random) components in solar activity.     

Temporal dynamics of dissolved organic carbon (DOC) produced in a microcosm with red tide forming algae <Emphasis Type="Italic">Chattonella marina</Emphasis> and its associated bacteria

Acute and severe hypoxia associated with harmful algal bloom has become one of the major causes for the environmental deterioration of coastal areas. Although it is generally thought that a large part of the dissolved oxygen consumption at a bloom site is initiated by heterotrophic bacteria that attack organic matter derived from dead or dying algal cells, precise microbial processes leading to the hypoxia are yet to be examined. Here we show temporal dynamics of extracellular dissolved organic carbon (DOC) of the red tide forming raphidophyte Chattonella marina and bacterial populations associating with the algae under laboratory conditions. During the growth of non-axenic strains of C. marina, we monitored abundance of algae, associated bacteria, and DOC in the culture media. Bacterial cell abundance increased in response to the increase in DOC both at the beginning and the late log phase of the algal growth. Flow cytometric analysis revealed that transient increase in the percentage of respiratory-active bacterial cells also coincided with the timing of the increase in bacterial abundance and DOC. These results strongly suggest that DOC released from growing C. marina fuels respiration and growth of planktonic bacteria surrounding the algae. This has implications for the role of DOC released from C. marina bloom before the collapse in mediating interactions between neighboring algae and bacterial assemblage which may eventually lead to algal bloom-associated hypoxia.     

Initial assessment of the COMPASS/BeiDou-2 regional navigation satellite system

An initial characterization and performance assessment of the COMPASS/BeiDou-2 regional navigation system is presented. Code and carrier phase measurements on up to three frequencies have been collected in March 2012 with a small regional network of monitoring stations. The signal and measurement quality are analyzed and compared with the Japanese Quasi Zenith Satellite System. A high level of stability is demonstrated for the inter-frequency carrier phase biases, which will facilitate the application of triple-frequency undifferenced ambiguity resolution techniques in future precise point positioning applications. The performance of the onboard Rubidium frequency standards is evaluated in comparison to ground-based hydrogen masers and shown to be well competitive with other GNSS satellite clocks. Precise orbit and clock solutions obtained in post-processing are used to study the presently achievable point positioning accuracy in COMPASS/BeiDou-2-only navigation. Finally, the benefit of triple-frequency measurements and extra-wide-lane ambiguity resolution is illustrated for relative positioning on a short baseline.