================================ EOT10a =================================

EOT10a stands for (E)mpirical (O)cean (T)ide model derived in 2010
by residual analysis of multi-missions (a)ltimeter data. The model 
is available at the anonymous ftp

    ftp.dgfi.badw.de  in directory   pub/EOT10a/data

The residual tide analysis for EOT10a was carried out with altimeter 
data of TOPEX, Poseidon, ERS-2, Jason-1, Jason-2, and ENVISAT, as far as 
acquired between October 1992 and April 2010. FES2004 was used as 
reference model for the residual tide analysis.

EOT10a consists of M2, S2, N2, K2, 2N2, K1, O1, P1, Q1, S1, Mm, Mf and M4 
tidal constituents each one tabulated on a 7.5'x7.5' geographical grid. 
The grids are stored as COARDS compliant NetCDF files. Accordingly, 
the file pattern in the   ../data   directory is
	xx.eot10a.nc		for ocean tides, and
	xx.eot10a.load.nc	for loading tides
where xx stands for any of the constituents listed above.

The tidal constants were stored in the complex form, eg. as cos- and sin-terms. 
The composition of the files is obtained by the netcdf command    
     ncdump -h  file.nc   
giving the following general information:

	Dimensions: 
x - number of nodes in the west-east-direction
y - number of nodes in the south-north-direction

Variables:
x (float) 	- longitudes of grid nodes [degree]
y (float) 	- latitudes of grid nodes [degree]
re(float) 	- real part of tidal constants [cm]  (amplitude*cos(phase))
im(float) 	- imaginary part of tidal constants [cm] (amplitude*sin(phase))

The grid files can be also handled by means of the Generic Mapping Tools 
(GMT), version 4.1 or higher. GMT is open source software, developed and 
maintained by Paul Wessel and Walter H.F. Smith (see http://gmt.soest.hawaii.edu/). 
For examples, if filename is replaced by the name of any of the netcdf files, 
then the commands

     grd2xyz filename?re
     grd2xyz filename?im

will print the real and the imaginary part of the corresponding constituent. 
Similar the commands

  grdmath filename?im filename?re HYPOT = ampl.grd   
  grdmath filename?im filename?re ATAN2 R2D = phases.grd
  
will compute amplitudes and phases in degree, which can subsequently 
printed by the GMT commands

     grd2xyz ampl.grd 		
     grd2xyz phas.grd                                                      

Plots for residual tidal constituents (wrt. thr reference model FES2004) may be 
found in the   ../plots  subdirectory. 

The development of EOT10a was funded by the Deutsche Forschungsgemeinschaft 
(DFG) under grant BO1228/5. EOT10a is a public model and it may be freely 
redistributed if appropriate reference is made to the report, mentioned below.

The EOT10a model is distributed in the hope that it will be useful, but DGFI 
provides EOT10a  "as is" without warranty, expressed or implied, as to the use 
or appropriateness of the EOT10a ocean tide model, and there are no warranties 
of merchantability or fitness for a particular purpose or use. 

          Roman Savcenko    and     Wolfgang Bosch
          
More detailed information on EOT10a will be given soon in 

Savcenko R., and W. Bosch (2010): EOT10a - empirical ocean tide model
    from multi-mission satellite altimetry. Report No. ??, Deutsches 
    Geodätisches Forschungsinstitut (DGFI), München (in press)

The pdf-version of this report will be provided in the directory pub/EOT10a/doc. 

August, 2010