Raising a pergola to build a deck

[brie121]

We have a part of our front yard with a drop-off of approximately 400mm between the lower ground level and the higher yard level. We plan to build a deck over this area at the higher ground level, with a pergola above the deck. However, if we cement the pergola posts directly into the lower ground level and then build the deck, the pergola posts will effectively start 400mm below the deck, making the pergola too short.

Is there a way to raise the base of the pergola posts so they align just under the deck level, maintaining the intended height of the pergola?

I’m unsure if it’s possible to use shorter posts and join them to extend the pergola legs, or if there’s a specific type of raised footing I can use to achieve this. 

Thanks