Monthly Mean Subsurface Temperatures in seas around Japan

   This directory contains the monthly mean subsurface temperature grid point
 values (GPVs) at the depths of 100m, 200m and 400m from January 1990 to the
 latest month.
   The temperature is determined for each 0.25x0.25 degree grid box in seas
 from 121E, 24N to 161E, 48N. 

   A function fitting method (Oceanographical Division, Marine Department,
 JMA, 1990) was used to determine the GPVs until December 2000. This method
 used the in situ observation data by research vessels, voluntary observing
 ships, buoys and floats, which are mainly obtained via Global Telecommunication
 System (GTS) of WMO.  A numerical data assimilation model (Kamachi et al.,1998)
 has been used since January 2001. The TOPEX/POSEIDON altimeter and the NOAA sea
 surface temperature data in addition to the above in situ observations are
 assimilated in this model.

   Reference:
 Kamachi,M., T.Kurogano, T.Yoshida, F.Uboldi and N.Yoshioka (1998):Development
 of mid-to-high-latitude Ocean Data Assimilation System (in Japanese). Weather
 Service Bulletin, 65, Special issue, 1-19
 Oceanographical Division, Marine Department, JMA (1990): An objective analysis
 of subsurface temperature (in Japanese). Weather Service Bulletin, 57,6, 271-
 282