Generally, it is our policy to not allow Google ads to open in a new window. However, in a few markets, including China, we've found that opening ads in a new window better aligns with expected internet behaviour and provides a more consistent, intuitive user experience.
Keeping in mind the importance of the user experience, we've enabled Google ads to open in new windows in locations where this is expected browsing behaviour. This functionality is determined by the IP of the user, and is not an option that you can select your AdSense account.
We also ask that you don't modify the AdSense ad code or alter the result of clicking an ad on your website, as such behaviour violates our programme policies.
