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* 1. README for the files with the names yyyymmddA2A4.TRK, where      *
*     yyyy, mm, and dd are year, month, and day, respectively.        *
*                                                                     *
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The files in this directory with the names yyyymmddA2A4.TRK, where 
yyyy, mm, and  dd are the year, month, and day respectively, contain
sea ice motion vectors in the Antarctic for the days indicated by 
the filenames. The sea ice motion vectors are obtained from QuikSCAT
data using a wavelet transform based ice tracking procedure developed
by Dr. Antony K. Liu's group at NASA/GSFC. The Antarctic QuikSCAT 
images used in the derivation of these sea ice motion vectors are 
produced by Dr. David G. Long's group at BYU using a scatterometer 
image reconstruction (SIR) resolution enhancement algorithm that 
enhance the resolution of the images to a pixel resolution of 4.45 km
from QuikSCAT level 1B 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 a 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 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 (pixel size=2.225 km). That is, 

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

The coordinates used here is DIFFERENT from SIR coordinates, the 
coordinates used in the BYU Antarctic QuikSCAT images with resolution 
4.45 km. The resolution (pixel size) of the coordinates used here 
is 2.225 km. To convert the coordinates use here to SIR coordinates
with 4.45 km resolution, use the following formula:

   X_sir = (x-1)/2+1  
   Y_sir = 1940-(4095-y)/2 

where (X_sir, Y_sir) stand for SIR coordinates starting from 1 and (x, y)
stand for the coordinates used in these files.

BYU SIR project provides c and IDL routines to convert between SIR coordinates
and longitude and latitude. 



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* 2. README for the files with the names yyyymmddA2A4.gif, where      *
*     yyyy, mm, and dd are year, month, and day, respectively.        *
*                                                                     *
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The files with the names yyyymmddA2A4.gif, where yyyy, mm, and dd are
year, month, and day, respectively, are the sea ice motion maps in the 
Antarctic in GIF format for the days indicated by the filenames. The sea 
ice motion maps plot the sea ice motion vectors on the daily QuikSCAT 
Antarctic images.