The envelope method introduced by Park et al. (2005) is used to estimate the surface arrival time of APEX-type floats. This is one of the most important parameters for estimating subsurface velocities accurately from float trajectories. However, the method does not work for APEX with the Park and Profile (PnP) observation scheme, at least in its original form, because each cycle of the APEX surface arrival time varies due to its depth control scheme: APEX's surfacing in PnP scheme is classified into two modes, earlier or later, which correspond to cycles with measurements deeper or shallower respectively than the preset profile depth. It is possible to improve the envelope method for APEX with the PnP scheme. However, obtaining additional information for improving the estimate is difficult considering the numerous gaps in the Argo data at present. Furthermore, it is expected that the results will be less accurate even if an improvement is made. The authors strongly recommend that the principal investigators (or Data Assembly Centers) identify the surface arrival times at data decoding, which is the easiest way to resolve this problem, and the method by which this can be achieved is explained herein.

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During three research cruises (KY05-14, KY07-01 and KY08-01) using JASMTEC R/V KAIYO, we obtained 13 heat flow data with piston core samples across the Nankai Trough and the Kashinosaki Knoll (KK). Subbottom temperatures were measured by precise thermometers attached to the piston corer. Thermal conductivity, color reflectance and vane shear strength were measured for the cored samples onboard KAIYO. Surface heat flow in the Nankai Trough north of KK ranges from 90-135 mW/m². With the sedimentation effects considered, basal heat flux beneath the Nankai Trough off Kumano is roughly estimated as 100-130 mW/m², most likely as 120-130 mW/m². In the Shikoku Basin south of KK, heat flow ranges 120-147 mW/m², (average∼135 mW/m²), significantly higher than the theoretical value (110 mW/m²) estimated from the age of the Shikoku Basin. Possible cause for the heat flow anomaly is either the postspreading volcanism at KK, thermal disturbance by tectonic compression at KK, or subseafloor fluid migration. More intensive study, including scientific drilling is necessary to estimate the accurate thermal structure of the incoming Shikoku Basin.

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The micro-focus XCT system is a powerful technique to visualize the inner structure of rocks nondestructively with 2.0μm resolution. Although the XCT image includes some errors resulting from beam hardening, ring artifacts, quantum noise and dependency on the condition of accelerating voltage and current, noise can be reduced by usage in the best imaging conditions. Quantitative treatment is possible in the same conditions with consideration of the cause of the error. We also constructed the transformation from grading on the micro-focus XCT image to a generalized CT value.

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Recently, it has become possible to record ‘live’ plankton in situ using new plankton-imaging technology, e.g. the Visual Plankton Recorder (VPR). For such technologies, automated plankton identification systems based on analysis of morphology, color, texture, and intensity patterns are also being developed. Some plankters are known to change their colors, which may have a severe effect on automated plankton identification systems. To investigate the effect of ambient light on their body color or their body color patterns, we conducted several preliminary experiments on the planktonic hyperiid amphipod Vibilia stebbingi by exposing it for 30 min under three types of light sources: fluorescent light bulb (white light), darkroom lamp (red light), and UV lamp (UV-A light). Color images of V. stebbingi were recorded at set intervals. In all cases, coloration darkened and body pigmentation patterns changed. These results suggest that for the development of automated plankton identification systems using color-images of plankton and incorporating image texture or coloration-based algorithms, more information on variations and changes in the coloration and pigmentation patterns of target zooplankton species may be needed.

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We produced a global monthly dataset of temperature and salinity using data from Argo floats, Triangle Trans-Ocean Buoy Network (TRITON), and available conductivity-temperature-depth (CTD) casts. The Argo project started from 2000, and the number of floats is increasing yearly throughout the global ocean. The Argo floats observe pressure, temperature and salinity from the sea surface down to 2000 dbar and enable the production of monthly global datasets of temperature and salinity. We have created Grid Point Value of the Monthly Objective Analysis using Argo float data (MOAA GPV) that contains optimally interpolated temperature and salinity values at selected standard pressure levels on a 1° grid in the global ocean. The dataset is freely available on the Argo website of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) at http://www.jamstec.go.jp/ARGO/J_ARGOe.html.

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During the JAMSTEC R/V Yokosuka YK08-08 Leg-1 cruise, the submersible Shinkai 6500 survey of the central Mariana Trough at 17°N was carried out to study a formation process of oceanic lithosphere in the active back-arc spreading center. Three dives were devoted to the median valley in the 17°N segment center. Visual observation of geology, lava flow morphology, and fault structure provides ground references for the backscattering imagery obtained from the deep-towed side-scan sonar survey conducted in 2003 to discuss volcanotectonic features. Smooth surfaces of side-scan imagery with high backscattering intensities are found to be jumbled-wrinkled, folded sheet, or lobate lava flows. The visual observation proves that the 17°N segment is covered with sheet lava flows of high effusion rates. Quantifiable degrees of sedimentation superposed on the lavas suggest relative age differences of formation. Sheet lava flows in the axial portion of the median valley are considered to be the youngest among the three dive observations. Sedimentation more or less gradually increases toward the western margin of the median valley. The observed eastern margin of the median valley is covered with sedimentary layers of ∼0.5-2 m thickness, thus the area is regarded as the oldest in our dive observations. North-south trending tectonic structures (i.e. faults, fissures), oblique to the median valley direction, could be younger than valley-parallel NNW-SSE trending structures because they show relatively little accumulation of sediment, and they cut the other structures in some places. Basaltic rock samples were collected at a total of 22 stations where several types of lava flow morphology are shown. Spatial variations in the rock faces, suggesting variations of chemical characteristics and rock ages, were found (phyric/aphyric, manganese coating, vesiculation). Hemipelagic sediment samples including nanofossils were also collected at 6 stations.

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Both pillow and sheet lava flows are distributed in the Mariana Trough back-arc basin axis at 17°N. These flows suggest different eruption rates, and they may indicate age variation in the lava. In this report we present observational results of sediments using a subbottom profiler (SBP) installed on the Shinkai 6500 during the YK08-08 Leg1 cruise. Observations from three dives (#1088 and #1089 on the western slope, #1090 on the eastern slope) with the SBP with visual observations and camera photos taken by the Shinkai 6500 were conducted to observe sediment on the lava flows. We estimate that the lava flow is new in dive #1088 because the SBP and visual observation cannot find sediment cover. In dive #1089 the sedimentary layer can be observed distinctly; moreover we can find a reflection within the sedimentary layer parallel to the basement. In dive #1090 we can find sediment cover by visual observation, but cannot determine sediment thickness by SBP observation. We consider the sediment coating in the dive #1090 survey area to be thinner than that in dive #1089. Therefore, it is possible to consider that these lava flows formed in the order #1089, #1090, and #1088.

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We carried out a deep wide-angle seismic experiment using a large airgun array and 110 ocean bottom seismographs (OBSs) along the Ogasawara Ridge from 26 November 2007 to December 25 (KY07-15 cruise) using R/V Kaiyo of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC). The Ogasawara Ridge is an extinct arc that was produced in Eocene period. In addition, this arc collided with the Ogasawara Plateau and this event is expected to have severely deformed the crust. The objectives of this cruise are to understand the typical characteristics of the Eocene arc and the crustal deformation by collision with the Ogasawara Plateau. An airgun-OBS seismic line with a length of approximately 594 km was set along the Ogasawara Ridge through the gentle southern root near the collision point by the Ogasawara Plateau. We shot a large airgun array with a total volume of 12,000 cu. in. and recorded the seismic signals on OBSs with four components and a 12-channel hydrophone streamer. Moreover, we investigated the northern elongation of the Eocene arc by reflection survey using a G-gun array with a total capacity of 600 cu. in. and a 16-channel hydrophone streamer. In this paper, we summarize the seismic experiments and introduce the OBS data and reflection data.

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The cruise, KR07-14, was organized by the Japanese-Chinese-Korean (JCK) Collaboration group, consisting of Drs. Chiaki Kato (JAMSTEC), Xiang Xiao (SOA) and Sang-Jin Kim (KORDI), called the JCK Japan Trench Investigation Cruise. The title of the cruise and the investigation area were as follows.
· Title: Analyses of microbial diversity and discovery of useful microbes and genes from the extremely deep sea bottom of the Japan Trench, by the Japanese-Chinese-Korean cooperation network.
· Investigation area: the Japan Trench off Sanriku at depths of 2,700∼7,000m.
We shared the deep-sea samples and experiments, and exchanged information. The results could then be published at science - journal quality regarding our successful collaboration. In this report, brief results of the cruise are described.

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