Seismic data from local size networks and a semi-global size network are being received at JAMSTEC. In order to systematically handle the data of the different network sizes, we attempted to apply SeisComP3, which is an earthquake monitoring system originally designed for detecting earthquakes or tsunamis in global or semi-global scales. On the other hand, it has been reported that many micro earthquakes are recorded in one of the networks, DONET. DONET is a local size network of ocean bottom seismometers deployed offshore of Kii peninsula. It is important to efficiently detect and list these earthquakes for the full utilization of the network data toward understanding the dynamics of the shallow part of the Nankai Trough. However, since the earthquake detection algorithm used in SeisComP3 focuses more on locating relatively large size earthquakes and minimizing the chance of detecting false events, some of the micro earthquakes do not get detected by the existing function of SeisComP3. Here, we developed a new SeisComP3 module, which binds signals detected at multiple stations within a certain distance and time span. We applied this module, which we call “binder”, to one daylong DONET data. We examined four types of bandpass filter, which have their bandwidth somewhere between 2 and 30 Hz, and concluded that the filter with corner frequencies at 4 and 20 Hz most efficiently detects the signal of the micro earthquakes. We confirmed that the binder is useful for detecting micro earthquakes. Moreover, one of the binder's advantages is that it works without assumptions on the velocity profile, thus it detected enigmatic events whose epicenters are located on the Kumano Basin and whose signal propagates at the velocity of around 1.5 km/s throughout the stations placed on the basin. No clear P arrivals were observed for these events. The finding demonstrates the possibility of the binder to become a useful tool to further explore the data and to find out more of different types of events, which have not been identified yet.

View full abstract

Blank level during the analytical process is critical for the determination of Os isotope ratios (¹⁸⁷Os/¹⁸⁸Os) both for high precision and accuracy. Previously, the blank level in the PGE laboratory was not good enough to measure samples with very low Os contents. To improve the blank level, we measured Os blanks in each reagent used in Os isotope analytical procedures by sparging method with ICP-QMS and tried to identify the source of Os blanks. Two major sources of Os blanks were identified; one is from nitric acid which is used in the digestion of samples, and the other is from environmental Os in the laboratory. We were able to decrease the Os blank in nitric acid to 1/3～1/2 than the original by heating and bubbling Air and N₂ gas into the nitric acid. To reduce the blank contribution from environmental Os, we used closed vaporization system during the evaporation of HBr sample solution. The closed vaporization system is quite efficient to prevent the air containing environmental Os for reducing the Os blanks. As a result, the Os blank level in our laboratory was reduced significantly for the analysis of ppt-level samples.

View full abstract

This study examines ocean currents and an eddy in open water region of the western Arctic Ocean using drifting buoy systems during the 2013 R/V Mirai Arctic cruise (MR13-06). In the Canada Basin, four buoys were deployed around the southern jet stream of the Beaufort Gyre, where two were deployed near the jet and others were around an anticyclonic eddy that was found in the central Canada Basin. To capture accurate current velocity, a holey-sock drogue was set at 50 m in depth around which representative currents for the jet and eddy exist. The buoys movement revealed that the jet was along a pathway parallel and close to the shelfbreak of the northern Chukchi Sea shelf, while the eddy migrated along with the jet as it rotated clockwise. At a stationary observation point in the Chukchi Sea shelf, we focused on and investigated the heat exchanges between the atmosphere and ocean during a transition from summer to winter (10 to 26 September). In the program, two buoys were used to examine ocean currents at upper and lower layers over the shelf. According to the buoy movement, it is found that oceanic currents were dominated by an inertial oscillation on the shelf throughout the observation period. A survey revisited the same water mass suggested that the sea water was mixed and modified by entrainment due to surface wind forcing and shear flow around depth of the main pycnocline in the two layer system.

View full abstract

March 2014

The Data Research Center (DrC) of JAMSTEC, established in 2009, has handled and disseminated various kinds of data and samples obtained by JAMSTEC as the result of its scientific research. It has been requested to make these valuable data and samples available for educational, societal and economical needs, as well as scientific purposes. Here, we review databases and dissemination systems of these data and samples, which we have developed during the past 5 years of the second midterm plan at the Data Research Center. We also review our recent activities to make our data available for societal needs and discuss some future directions.

Seiji Tsuboi
Deta Research Center for Marine-Earth Sciences
Japan Agency for Marine-Earth Science and Technology

View full abstract

JAMSTEC has established Basic Policies on the Handling of Data and Samples in May 2007 and started its operation in 2008. The Data Research Center of JAMSTEC, established in 2009, has handled these various kinds of data and samples obtained by JAMSTEC as the result of its scientific research, on the basis of these basic policies. Here we review databases and dissemination systems of these data and samples, which we have developed during the past 5 years of the second midterm plan at the Data Research Center. The database systems include the Data Research System for Whole Cruise Information (DARWIN), JAMSTEC E-library of Deep-sea Images (J-EDI), Biological Information System for Marine Life (BISMAL) and sample databases. We also review our recent activities to make our data available for societal needs and discuss some future directions.

View full abstract

Data Research Center for Marine-Earth Science (DrC) unifies management of the observation data, samples and deep-sea images obtained from JAMSTEC research cruises and dives. In order to correctly and effectively handle these data, JAMSTEC collects a 'metadata sheet' in which onboard scientists, technical staffs and crews record the basic research information from each cruises. DrC developed a database system for comprehensive management of these metadata. JAMSTEC carries out observations on the land as well as in the ocean. These metadata from the land observations is also handled in the system. This database system, which has a user interface accessible via web browser, has functions for supporting data management staffs to carry out data dissemination activities and research information review of the past cruises and dives. This system is accessible only in DrC, because it includes confidential information. However the system plays an essential roll to keep smooth service to public data users.

View full abstract

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) are operating about one hundred of research cruises every year. The collected data are published at multiple JAMSTEC data sites as part of the metadata-tagged geo-environmental data maintained by Data Research Center for Marine-Earth Sciences (DrC). At DrC , continuous efforts are being made to improve usability (user-friendliness) of the data sites and the related databases. In this article, we report some progresses made recently on the ocean-observation database “Data Research System for Whole Cruise Information in JAMSTEC (DARWIN)”, and the deep seafloor rock sample database'' Geochemistry and Archives of ocean floor rocks on Networks for Solid Earth Knowledge Integration (GANSEKI)''.

View full abstract

The Data Research Center for Marine-Earth Sciences of the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) manages many deep-sea videos and photos obtained from manned/unmanned research submersibles owned by JAMSTEC. The database system “JAMSTEC E-library of Deep-sea Images (J-EDI)”, which is being operated at the Global Oceanographic Data Center (GODAC) since its development in 2011, has made these videos and photos available to the public via the Internet. There is no other web system distributing various deep-sea environmental images in large numbers. Original video data recorded in JAMSTEC's submersibles are transcoded into a format for web streaming, and photo data are resized. Furthermore, they are annotated with subject details (e.g. living organisms, geography, environments and others) by GODAC staffs. The number of videos and photos with annotations has increased drastically using J-EDI. On the other hand, although it is necessary to distribute deep-sea image data in a suitable format for use, there is a problem that the process of making videos for web streaming has been complicated by the diverse formats of the original video data. In addition, annotations are effective to search for the target data from a large amount of data, but a broad scientific knowledge on deep-sea environments is required for detailed identification of objects in images. Many of current annotation contents on J-EDI provide only rough taxonomic information of living objects. To improve the situation, collaboration with specialists in the annotation process will be necessary.

View full abstract

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) built the database, Biological Information System for Marine Life (BISMaL), to integrate and publish biodiversity information collected by JAMSTEC. Among the information handled on BISMaL, occurrence records of marine organisms has been compiled to Ocean Biogeographic Information System (OBIS) to share marine biodiversity information internationally and has been used for researches in related fields. However, the information about the Japanese species and deep-sea taxa are still insufficient. Therefore, JAMSTEC started to provide the data to OBIS via BISMaL. Furthermore, a new framework, the Japan Regional OBIS Node, to collect data of marine species around Japan was launched, and the data publication through BISMaL was started. These efforts will be further progressed and contribute to marine biodiversity studies around Japan.

View full abstract

A habitat suitability index (HSI) model for the neon flying squid (Ommastrephes bartramii) in the North Pacific has been developed under the on-going national research program “Research Program on Climate Change Adaptation” (RECCA), and successfully estimated the accurate potential fishing zone around the date line in summer, by applying the MOVE ocean reanalysis product which can provide realistic fields of 3-dimensional ocean circulation and environmental structures. Furthermore, the delivery of daily maps of the squid HSI and other ocean environmental fields (SST, SSH, chl-a, sub-surface temperature etc.) through the internet for Japanese fishing vessels was conducted in 2012, and the interviews with users were carried out after the fishing period to investigate the availability of the web-site. The results demonstrate that the information of the potential fishing zone of neon flying squid has the effective impact for adaptive fishery operation with low cost and reduction of CO₂ emission.

View full abstract

To reproduce the dynamical states of global climate on seasonal and inter-annual scales, a four-dimensional variational (4D-VAR) data assimilation system with a coupled ocean-atmosphere global model has been successfully developed in Data Research Center for Marine-Earth Sciences (DrC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC). Our 4D-VAR coupled data assimilation (CDA) system with a three-month assimilation window runs routinely in every three months since January 2010 and generates sets of reanalysis data and ensemble three-year climate prediction data. To realize further efficient production of reanalysis data sets, DrC develops a production support system for synthesizing reanalysis data. It comprises the three subsystems for (a) automated observational data acquisition with a “cron” process, (b) quality control and data processing, and (c) synthetic visualization of observational and reanalysis data. With the support system, we evaluate performance of the sets of the three-month reanalysis and three-year ensemble prediction data. The majority of the data sets hold higher reproducibility in the three-month assimilation periods and predictability in the first one-year ensemble prediction periods over the tropical ocean states in the Pacific and Indian oceans. The support system, in particular, for synthetic visualization plays a crucial role to evaluate the reanalysis and prediction data.

View full abstract