Deck Footing question above ground or no?

About ready to submit my plans for a residential deck in NJ. Code looks to be 22" footing diameter and 9" of thickness buried to 30". Everything I see recommends having the footings about 4" about grade. Setting it up with a 22"x9" footing would leave me with 21" of buried post. I don't think this is optimal. My questions is if I increase the footings to 34" (so that they are buried to 30" and I have 4" above grade) what is the acceptable diameter.. do I still need 22"? Thanks in advance