Kathi,
Here's what the folks at one of the Antarctic sites had to say about the 'blackout' satellite images:
(Must admit, not certain I completely understand it...)
----------begin e-mail------
>Hi! Great site.
>Can you tell us what the 'blackout' areas are about?
>
>http://uwamrc.ssec.wisc.edu/~amrc/compmovie.html
>
>Appreciate it.

>E.

-----answer e-mail----------
Sure can:

The Antarctic composite may have regions that are blacked out. These areas of
black space, other than the latitude and longitude lines and continent
outlines, indicate missing imagery or a lack of satellite coverage.

Basically, we do not include any data unless it is with +/- 50 minutes of
the top of the synoptic hour the composite is made. That way no old
data is there. Thus, we leave the missing data areas with no satellite coverage
that would were able to get a hold of as black.

I hope this helps! Glad you enjoy the site!

Matthew

-----------------------------------------------------------------------
Matthew Lazzara - Meteorologist - Antarctic Meteorological Research Center
Space Science and Engineering Center E-mail: mattl@ssec.wisc.edu
University of Wisconsin-Madison Phone: (608) 262-0436
1225 West Dayton Street, Madison, WI 53706 Fax: (608) 263-6738
-----------------------------------------------------------------------