Remove blank line above Adsense blocks please?

Hi, I wonder if someone could help me please?
I use twentytwelve & have a fixed page for my homepage.
Beneath the header image I want to type my text intro, with an Adsense block aligned top right hand corner of the opening text. After the first couple of paragrpahs I want a second Adsense block aligned on the left of that text, and finally at the foot of page a wide banner advert.

My problem is that all of the Adsense ads have a leading blank line or space above them, and this makes the page look awkward. There’s no hidden spaces or blank lines and I can’t see any way to remove these?

Found this difficult to explain, hope it makes sense?

Thanks