JAHMP-XBT/XCTD Data Archive


General Information
  1. JAHMP (Japan-Hawaii Monitoring Program) is a joint research project between Physical Oceanography Laboratory of Tohoku University and Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for hydrographic monitoring of the western North Pacific. The program is enabled by courtesy of Miyagi Prefecture and the crew of Miyagi Maru.
  2. All data on this web site were obtained by the XBT (Expendable Bathythermograph) / XCTD (Expendable Conductivity-Temperature-Depth profiler) measurements that were conducted during three-times a year cruises of the ship from Honolulu, Hawaii, to Japan.
  3. The measurement cruises are almost fixed at March, June and October/November of a year. However, the months were different in some years due to the change of the ship's schedule.
  4. Measurements were basically done every 30 minutes in longitude from 160 degree west on the ship's route from Honolulu to Japan. Originally all measurements were done by XBT(TSK T-7), Since 2000, measurements at points every 5 degrees have been replaced by XCTD-1.
  5. Locations of the measurements vary from year to year because of the sea state and operational reasons of the ship. Actually, PX-40 is a 'zone' rather than a 'line'. See cruise track and Position Files of each cruises for more detail information.
  6. Only the 1m-resolution temperature data are available on this web site.

History of JAHMP

How to download datafiles

Follow link in the column of "year & month" of your interest, in the calendar-like table below (the bottom frame). The cruise track and the temperature section will then appear in the middle (this) frame. You can obtain temperature data by clicking "Download Temperature Data" and position files by "Positions" there.


Data processing
  1. All data from the surface to 19th raw sampling are replaced by 20th temperature to eliminate the effect of transient behavior of the temperature sensor upon entry to the water.
  2. Time-depth conversion is made according to the fall-rate equation of Hanawa et al. (1995) for T-7 XBT and the manufacturer's equation for XCTD-1.
  3. Data are interpolated to 1 meter resolution in depth.
  4. Seven-point median filter is applied to exclude spike-wise measurement noise which sometimes (not often) comes in.

File Format
  1. Data files are archived and compressed for each cruise by Unix/Linux "tar" and "gzip" commands. Use "ungzip" and "tar xvf ..." to recover original files.
  2. Temperature data (1 meter resolution) are stored from the 2nd and later records (lines) of the files. The first temperature is at the surface, and 1 meter depth, 2 meters depth, ... and so on. Each record (line) contains 10 depth points (i.e. the 2nd record of the files includes temperatures at points from the surface to 9 meters depth).
  3. See Position Files for dates and locations of individual measurements.
  4. Station Numbers (STN#) for XBT measurements and those for XCTD measurements are not uniquely given in some cruises. For example, you could find two "X001" data files obtained at different locations: one for XBT measurement at a point and the other for XCTD measurement at another point. In other words, STN# is an identifier for a file name but not that for a geographical point.

Terms and Conditions
  1. All data here are limited to use for personal browsing and scientific research only.
  2. The copyright of all text, figures and photographs on this web site belong to Shoichi Kizu.
  3. Redistribution of all data on this web site is prohibited.
  4. Setting link to this web site is free.
  5. Please describe the source of data and send a couple of copies of the document (reprints, for example) to the following address when you publish or present any scientific achievements based on our data.

Contact person

References

Hanawa, K., P. Rual, R. Bailey, A. Sy and M. Szabados (1995): A new depth-time equation for Sippican or TSK T-7, T-6 and T-4 expendable bathythermographs (XBT). Deep-Sea Res., 42(8), 1423-1451.

Kizu, S., and K. Hanawa (2002): Start-up transient of XBT measurement by three types of Japanese recorder system. Deep-Sea Res., 49(5), 935-940.

Uehara, H., S. Kizu, K. Hanawa, Y. Yoshikawa and D. Roemmich (2008): Estimation of heat and freshwater transports in the North Pacific using high resolution XBT data. J. Geophys. Res., 113, C02014, doi:10.1029/2007JC004165.


Links

Scripps Institution of Oceanography High-Resolution XBT/XCTD Network Site

Ship of Opportunity Programme (SOOP)

JCOMM Ship Observation Team (SOT)


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