Assuming you have signed up for AdSense and been accepted yes, the ads that show up should be tied directly to your Google AdSense account. Google now owns Blogger so when you add your AdSense ads, they make it convenient to display your ads.

The Hurricane Katrina ads are PSA's (Public Service Announcments) and they usually show up on your site when Google can't find any relevant ads to match your content.

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Severely Addicted to AdWords