*** README for the files with the name yyyymmddA2A4mcpx.TRK ****

The files in this directory with the name yyyymmddA2A4mcpx.TRK, where yyyy, mm,
and  dd are the year, month, and day respectively, are merged ice motion 
vector files for the specific day indicated by the filename in the Arctic 
from ice tracking results of QuikSCAT, SSM/I, and buoy data. Each file is in
ASCII format and has 15 lines of header. The first line of the header 
indicates how many vectors are in this file. The second line of the header
indicate tracking period. If tracking period =4, this means that we use 
4-day sliding window in our tracking routine.  The 12th line of the header 
gives the resolution (pixel size) used in the tracking routine. The rest 
part of the header is useful mainly for internal ice tracking process. 

Beginning from 16th line, each line contains starting point, ending point, and
displacement information for an ice motion vector. The format for each line
is the following:

    x1, y1, x2, y2, disp

where (x1, y1) are x- and y-coordinates of the starting point,  (x2, y2)
are x- and y-coordinates of the ending point, and disp is the 
displacement of the ice in pixels. That is, 

 displacement=SQRT((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)).

Note that the displacement is the displacement in the tracking period. That is,
if 4-day sliding window is used as indicated by the second line of the header,
the displacement is the displacement in 4 days. The coordinates used here
 is different from standard SSM/I coordinates (with resolution 12.5 km). To 
convert the coordinates use here to SSM/I coordinates with 12.5 km resolution, 
use the following formular:

   X_s = x+41 
   Y_s = (1023-y)+251 

where (X_s, Y_s) stand for SSM/I coordinates starting from 1 and (x, y) stand 
for the coordinates used in these files.

To convert from SSM/I coordinates to longitude and latitude, one can use 
the FORTRAN programs found in the SSM/I data distribution CDROM. The program
can convert from SSM/I coordinates to longitude and latitude or from longitude
and latitude to SSM/I.