It's acceptable (or at least “not wrong”) to use “aa” for å (and “oe” for ø/ö, “ae” for æ/ä).
While ‘å’ was made an official letter in Norwegian in 1917, it's still common to see “aa” spellings of names, and “aa” and “å” spellings are considered equivalent (fun when sorting, since ‘å’ is the last letter of the Norwegian alphabet).
While ‘å’ was made an official letter in Norwegian in 1917, it's still common to see “aa” spellings of names, and “aa” and “å” spellings are considered equivalent (fun when sorting, since ‘å’ is the last letter of the Norwegian alphabet).