http://www.sciencedirect.com/science/article/pii/S1674987112001028

A study on the effect of the solar ultra-violet radiation on the human skin fibroblast cells revealed that the production of matrix metalloproteinase-2 was inhibited by the radiation.A CO2 incubator connected by optical fibers to a reflector telescope for collecting the solar light was built at Syowa station by the 49th Japanese Antarctica Research Expedition.The direction of the telescope was continuously controlled by a sun-tracker to follow the movement of the Sun automatically.The intensity of the collected light was monitored by a portable spectrophotometer housed inside.The human skin fibroblast cells were incubated in the CO2 chamber to investigate the effect of the solar radiation at Syowa station and were compared with those reference experiments at a laboratory in Japan.The results showed cell damage by strong UV radiation.The production of matrix metalloproteinase-2 was prompted by the moderate UV-B,but was inhibited by the strong UV-B radiation,as studied under laboratory conditions in Japan.The effect of strong solar radiation at Syowa station involving the radiation of UV-B region was estimated to be of the same extent of the radiation caused by an artificial UV-B light with the intensity more than 50 mJ/cm2.     

Concentration mechanisms of iron oxides and alumina in deep weathering crusts (Goshikidai, Kagawa, Western Japan)

Concentration of Fe-oxides and alumina in weathering processes are main geological reactions for lateritization and bauxitization, respectively. In western Japan, red-coloured soil formed by weathering processes developed in many places. This soil is composed of hydrous Fe-oxide minerals, hydrous alumina minerals and other minerals. It was formed in the upper part of deep weathering crust by weathering processes under some kind of sub-tropical climate, probably in the Pliocene. One of these occurrences is observed in the upper part of Goshikidai and Konodai, west part of Takamatsu city, northeast Shikoku Island, west Japan. A deep weathering crust is distributed on wide hilly plains ranging from 250 to 400 m a.m.s.l. in the northwestern region of Takamatsu city. Original rock of the weathering crust is bronzite andesite and glassy bronzite andesite, so-called ‘sanukite’. The andesites had been weathered under some special climate, and the geological age of the weathering is the same as above. The mineral assemblage and formation mechanism are similar to those of laterite and bauxite. The weathering crust developing in this region are subdivided into the three following zones: (1) A zone, composed of hydrous Fe-oxides and metahalloysite with small amounts of gibbsite and it is associated with white veins of metahalloysite; (2) B zone, composed of hydrous Fe-oxides and metahalloysite (some material is associated with -cristobalite); and C zone, composed of metahalloysite or halloysite and -cristobalite with relict crystals of feldspar and quartz, and some material is associated with montmorillonite. Chemical analyses of the materials of the three zones show the formation mechanisms of the weathering crust.     

A 100 m laser strainmeter system installed in a 1 km deep tunnel at Kamioka, Gifu, Japan

We have installed a laser strainmeter system in a deep tunnel about 1,000 m below the ground surface at Kamioka, Gifu, Japan. The system consists of three types of independent interferometers: (1) an EW linear strainmeter of the Michelson type with unequal arms, (2) an NS-EW differential strainmeter of the Michelson type with equal arms and (3) a NS absolute strainmeter of the Fabry–Perot type. These are configured in L-shaped vacuum pipes, each of which has a length of 100 m. (1) and (2) are highly sensitive (order of 10⁻¹³ strain) and have wide dynamical range (10⁻¹³–10⁻⁶). Observations with strainmeters (1) and (2) started on June 11, 2003. (3) is a new device for absolute-length measurements of the order of 10⁻⁹ of a long-baseline (100 m) Fabry–Perot cavity by the use of phase-modulated light. This third strainmeter will be ready for operation before the end of 2004. The laser source of strainmeters (1) and (2) is a frequency-doubled YAG laser with a wavelength of 532 nm. The laser frequency is locked onto an iodine absorption line and a stability of 2 × 10⁻¹³ is attained. The light paths of the laser strainmeter system are enclosed in SUS304 stainless steel pipes. The inside pressure is kept to be 10⁻⁴ Pa. Consequently, quantitative measurement of crustal strains of the order of 10⁻¹³ can be attained by employing the laser strainmeter system of (1) and (2) at Kamioka. This resolving power corresponds to that of a superconducting gravimeter. Using the laser strainmeter system, we expect to determine parameters related to fluid core resonance, core modes and core undertone as well as other geodynamic signals such as slow strain changes caused by silent earthquakes or slow earthquakes.     

A flare model deduced from Hinotori and millimeterwave interferometer observations

The -ray and white-light flare of 13 May, 1981 is used for a study of spatial distributions of energetic electrons and high-temperature plasma.     

Scale dependence of accumulation-dispersal coefficient of marine organisms

An attempt is made to find a relation betweenK, the absolute value of accumulation-dispersal coefficient of marine organisms referred to a region or a group (Kawai, 1986a), andL, the square root of the area of the region or the group over which the distribution density of organisms is averaged.K is estimated as shown below. For appropriate sampling time-intervals,K becomes greater than other coefficients such as population growth coefficient. Using this result, an order of magnitude ofK dependent onL is estimated from various data of temporal change in density. With the aid of a dependenceQL ^–2/3 (Kawai, 1985b), a relationKL ^–2/3 is predicted for 30 cmL 30 km, whereQ andK are the root-mean-square values of area-averaged horizontal divergence of near-surface flows and of the accumulation-dispersal coefficient, respectively. The reason whyK tends to have the order of magnitude of weak or mediumQ is discussed. The doubling-halving time of the distribution density due to accumulation-dispersal,T, is related toK byT=(log_e2)/¦K¦L ^2/3. Finally, sampling time-intervals to estimate accumulation-dispersal coefficients are referred to.     

Aeolian dust experiment on climate impact: An overview of Japan–China joint project ADEC

The Aeolian Dust Experiment on Climate Impact (ADEC) was initiated in April 2000 as a joint five-year Japan–China project. The goal was to understand the impact of aeolian dust on climate via radiative forcing (RF). Field experiments and numerical simulations were conducted from the source regions in northwestern China to the downwind region in Japan in order to understand wind erosion processes temporal and spatial distribution of dust during their long-range transportation chemical, physical, and optical properties of dust and the direct effect of radiative forcing due to dust. For this, three intensive observation periods (IOP) were conducted from April 2002 to April 2004.The in situ and network observation results are summarized as follows: (1) In situ observations of the wind erosion process revealed that the vertical profile of moving sand has a clear size dependency with height and saltation flux and that threshold wind velocity is dependent on soil moisture. Results also demonstrated that saltation flux is strongly dependent on the parent soil size distribution of the desert surface. (2) Both lidar observations and model simulations revealed a multiple dust layer in East Asia. A numerical simulation of a chemical transport model, CFORS, illustrated the elevated dust layer from the Taklimakan Desert and the lower dust layer from the Gobi Desert. The global-scale dust model, MASINGAR, also simulated the dust layer in the middle to upper free troposphere in East Asia, which originated from North Africa and the Middle East during a dust storm in March 2003. Raman lidar observations at Tsukuba, Japan, found the ice cloud associated with the dust layer at an altitude of 6 to 9 km. Analysis from lidar and the radio-sonde observation suggested that the Asian dust acted as ice nuclei at the ice-saturated region. These results suggest the importance of dust's climate impact via the indirect effect of radiative forcing due to the activation of dust into ice nuclei. (3) Studies on the aerosol concentration indicated that size distributions of aerosols in downwind regions have bimodal peaks. One peak was in the submicron range and the other in the supermicron range. The main soluble components of the supermicron peak were Na⁺, Ca²⁺, NO₃⁻, and Cl⁻. In the downwind region in Japan, the dust, sea salt, and a mixture of the two were found to be dominant in coarse particles in the mixed boundary layer. (4) Observation of the optical properties of dust by sky-radiometer, particle shoot absorption photometer (PSAP), and Nephelometer indicated that unpolluted dust at source region has a weaker absorption than originally believed.A sensitivity experiment of direct RF by dust indicated that single scattering albedo is the most important of the optical properties of dust and that the sensitivity of instantaneous RF in the shortwave region at the top of the atmosphere to the refractive index strongly depends on surface albedo. A global scale dust model, MASINGAR, was used for evaluation of direct RF due to dust. The results indicated the global mean RF at the top and the bottom of the atmosphere were − 0.46 and − 2.13 W m^− 2 with cloud and were almost half of the RF with cloud-free condition.     

Volcanic and Tectonic Framework of the Hydrothermal Activity of the Izu–Bonin Arc

In the Izu–Bonin Arc, hydrothermal activities have been reported from volcanoes along present‐day volcanic front, a rear arc volcano and a back‐arc rift basin as well as a remnant arc structure now isolated from the Quaternary arc. It is widely known that characteristics of hydrothermal activity (mineralogy, chemistry of fluid etc.) vary depending upon its tectonic setting. The Izu–Bonin Arc has experienced repeated back‐arc or intra‐arc rifting and spreading and resumption of arc volcanism. These characteristics make this arc system a suitable place to study the tectonic control on hydrothermal activity. The purpose of the present paper is, therefore, to summarize volcanotectonic setting and history of the Izu–Bonin Arc in relation to the hydrothermal activity. The volcanotectonic history of the Izu–Bonin Arc can be divided into five stages: (i) first arc volcanism (boninite, high‐Mg andesite), 48–46 Ma; (ii) second arc volcanism (tholeiitic, calc‐alkaline), 44–29 Ma; (iii) first spreading of back‐arc basin (Shikoku Basin), 25–15 Ma; (iv) third arc volcanism (tholeiitic, calc‐alkaline), 13–3 Ma; and (v) rifting in the back‐arc and tholeiitic volcanism along the volcanic front, 3–0 Ma. Magmas erupted in each stage of arc evolution show different chemical characteristics from each other, mainly due to the change in composition of slab‐derived component and possibly mantle depletion caused by melt extraction during back‐arc spreading and prolonged arc volcanism. In the volcanotectonic context summarized here, hydrothermal activity recognized in the Izu–Bonin Arc can be classified into four groups: (i) present‐day hydrothermal activity at the volcanic front; (ii) active hydrothermal activity in the back arc; (iii) fossil hydrothermal activity in the back‐arc volcanoes; and (iv) fossil hydrothermal activity in the remnant arc. Currently hydrothermal activities occur in three different settings: submarine caldera and stratocones along the volcanic front; a back‐arc rift basin; and a rear arc caldera. In contrast, hydrothermal activities found in the back‐arc seamount chains were associated with rear arc volcanism in Neogene after cessation of back‐arc spreading of the Shikoku Basin. Finally, sulfide mineralization associated with boninitic volcanism in the Eocene presumably took place during forearc spreading in the initial stage of the arc. This type of activity appears to be limited during this stage of arc evolution.     

Outflow of water from Funka Bay,Hokkaido, during early spring

Observations were made to study the oceanographic structure of the dense water formation and its outflow from Funka Bay, Hokkaido, during early spring. The winter Funka Bay water, which was transformed from the warm water of the Tsugaru Current, due to cooling and deep convection during the winter, flowed from the bay, while forming a frontal structure. The width and inclination of the density front were about 3 n. miles and 1.4×10^?2, respectively, during the early spring of 1982. These values roughly coincided with calculated values of 2.6 n. miles and 1.7×10^?2 using the sill flow model proposed by Whiteheadet al. (1974). Observed current speeds and directions were also similar to those predicted by the model. The renewal time of bay water with this flow was estimated to be about 51 days, which is consistent with the results of previous studies.     

Characteristics of SSH Anomaly Based on TOPEX/POSEIDON Altimetry and in situ Measured Velocity and Transport of Oyashio on OICE

An observation line along the TOPEX/POSEIDON (T/P) ground track 060 was set to estimate the Oyashio transport. We call this line the OICE (Oyashio Intensive observation line off-Cape Erimo) along which we have been conducting repeated hydrographic observations and maintaining mooring systems. T/P derived sea surface height anomaly (SSHA) was compared with velocity and transport on OICE. Although the decorrelation scale of SSHA was estimated at about 80–110 km in the Oyashio region, the SSHA also contains horizontal, small-scale noise, which was eliminated using a Gaussian filter. In the comparison between the SSHA difference across two selected points and the subsurface velocity measured by a moored Acoustic Doppler Current Profiler (ADCP), the highest correlation (0.92) appeared when the smoothing scale was set at 30 km with the two points as near as possible. For the transport in the Oyashio region, the geostrophic transport between 39°30′ N and 42°N was compared with the SSHA difference across the same two points. In this case the highest correlations (0.79, 0.88 and 0.93) occurred when the smoothing scale was set at 38, 6 and 9 km for reference levels of 1000, 2000 and 3000 db, respectively. The annual mean transport was estimated as 9.46 Sv in the 3000 db reference case. The Oyashio transport time series was derived from the T/P SSHA data, and the transports are smaller than that estimated from the Sverdrup balance in 1994–1996 and larger than that in 1997–2000. This difference is consistent with baroclinic response to wind stress field. This revised version was published online in July 2006 with corrections to the Cover Date.