Sea Surface Height in the Pacific

  This directory contains gridded Sea Surface Dynamic Height (SSDH) and  Sea Surface
 Height Anomalies (SSHA) from January 2003 to the latest date. These are determined 
for 0.25 degree latitudinal and longitudinal squares in the seas between 28S and
56N from 118.75E to 79.5W every 5days.
  (SSHD and SSHA were not analyzed in the area east of 99.5W before 2 June 2003).

  SSDH and SSHA are analyzed at the Office of Marine Prediction of the JMA. The
analysis uses Jason-1 Interim Geophysical Data Record (IGDR) provided by Physical
Oceanography Distributed Active Archive Center (PO.DAAC) at Jet Propulsion
Laboratory (JPL).
(a) SSHA
  SSHA from 1993-1996 mean sea surface height is calculated along satellite ground
track. Applying Gaussian filter to the along-track SSHA with cutoff wavelength of 
800 km, SSHA is decomposed into eddy-scale and large-scale SSHAs.  Gridded SSHA is
calculated by using 3-dimensional space-time optimum interpolation applied to the
decomposed along-track SSHA. SSHA field is sum of eddy-scale and large-scale gridded 
SSHAs( Kuragano and Kamachi, 2000; Kuragano and Kamachi, 2003). 
(b) SSDH
  SSDH is a sum of SSHA and an averaged SSDH for period from 1993 to 1996.  
The averaged SSDH was calculated by the method of Kuragano and Shibata (1997).
 
  SSDH and SSHA analysis are made twice for the same analysis date. The former, 
a prompt analysis, is produced about 5 days after the analysis date.  
For example, the file 'ssdh.Jan03' of the prompt analysis is made on 8th January.
The latter, a final analysis, is produced in 8-30days after the analysis date.  
The prompt analysis is performed with only data prior to the analysis date, while
the final one with both prior and posterior to the date.  The file of prompt 
analysis is overwritten by that of final analysis.    

  The IGDR is provided for the purpose of the operational use, and the products here,
therefore, are also provided for the same purpose.  Users should use the Geophysical
Data Record (GDR) for their research activities.

Directory structure
           ssh
            |___README (This Document)
            |
            |___ssdh(sea surface dynamic height)
            |                 |
            |                 |___YYYY(Directory for the data file)
            |                         |__ ssdh.Jan03
            |                         |__ ssdh.Jan08
            |                                 :
            |                                 :
            |___ssha(sea surface height anomalies)
                              |
                              |___YYYY(Directory for the data file)
                                      |__ ssha.Jan03
                                      |__ ssha.Jan08
                                              :
                                              :                              
where  YYYY is a year  (e.g. 2003)

Data format 
  Each data set consists of 337 records, one header record and following
336 data records from north to south in order.	The header record contains 
the year, month and day in  3I4. Each data record is written as 647I3 from west to
east, with unit in 'cm'.  The first value of the first data record is for the grid
centered at 55.875N and 118.875E, and the last value of the last data record is for
that at 27.875S and 79.625W, respectively.  '999' is placed on the grid on land or
the grid where SSHA and SSDH cannot be determined.

References:

Kuragano, T. and A. Shibata (1997): Sea surface dynamic height of the Pacific
    ocean derived from TOPEX/POSEIDON altimeter data: Calculation method and 
    accuracy, J. Oceanogr., 53, 585-599.

Kuragano, T. and M. Kamachi (2000): Global statistical space-time scales of 
    oceanic variability estimated from the TOPEX/POSEIDON altimeter data, 
    J. Geophys. Res., 105, 955-974.

Kuragano, T. and M. Kamachi (2003): Altimeters capability of reconstructing
    realistic eddy fields using space-time optimum interpolation, J. Oceanogr., 
    in press.

  For further information, please contact the Regional Real Time Data Base at 
neargoos@climar.kishou.go.jp