Daily Sea Suaface Temperature Data analysis by
Japan Meteorological Agency (JMA)
This file contains analysis data of SST provided by the Japan Meteorological
Agency. Each file consists of 121 lines of characters. The first line indicates
the date of the analysis, as below.
1997 4 1 1997 4 1 1997 4 1
The second line is the data for the band between 49.75 to 50 degrees
North. A 0.25 by 0.25 box data are presented with three digit integers
in tenth of degrees Centigrade from 110 to 110.25 degrees East to 159.75
to 160 degrees East. The third line and onward are similar but the latitude
goes southward to between 20N and 20.25N in the 121st line. The following
is an example of FORTRAN statements to read the data. 999 and 888 mean
land and sea ice, respectively. 777 means that the data is unknown for
c isst(1,1) = sst in 49.75N to 50N, 110E to 110.25E
c iy, im, and id are year, month, and day
do 100 j=1,120
Note on the SST analysis
JMA started, in March 1996, daily high resolution sea surface temperature
(SST) analysis for the region between 20N and 50N and between 120E and
160E. The resolution is a quarter degree.
An optimal interpolation method is employed and the first guess field is
given by linearly interpolating the climatological SST data of every one
degree that JMA produced. The parameters used in the optimal interpolation
are determined by examining the statistical characteristics of observations.
The analysis uses sea surface observation by NOAA and the in situ observation
by ships and buoys. The data from the ships which make reports with bias
or standard error larger than that of typical observation vessels are excluded
from the process. The all the in-situ data within the spacial and temporal
box of 1 day * 0.25 degree * 0.25 degree are averaged to give a representative
value for that box, and these representative values are fed to the optimal
interpolation as the 'observations'.
To get the interpolated value at each of the grind points, the 'observations'
for the past 5 days within a half of the the typical spacial scale of the
variation for the points are used. The typical spacial scale of the variation
is estimated by examining the NOAA sst and varies from 40 km to 400km.
In practice, in order to ensure that the interpolation is made with a sufficient
number of input data, the minimum scale is set to be 200 km.
For further information, please contact the Real Time Data Base at