The ice dragon is not an ice dragon in the true sense that it is cold and breathes ice instead of fire. The ice dragon is actually a constellation of stars. The North Grove is located beneath the ice dragon because it is underneath the stars in the sky.
There are other debates about the meaning of the ice dragon. Some people wonder whether or not it is an undead dragon, or a completely different species, or something else entirely. Personally, the theory of the ice dragon really being a constellation makes the most sense to me and the symbolism is beautiful and deep.