I think both Bose-x and Islander2 are both correct but are talking at cross purposes to each other.
Bose-x has worked out the Pressure Altitude (from Sea Level). Islander2 has worked out Aerodrome Pressure Altitude - which is what the question wanted, but is a term I've never heard of before (and probably why Bose-x's computer thingies haven't either). I'm not quite sure why you would want to know the Aerodrome Pressure Altitude other than to say to yourself that today my aircraft performance will be 630ft worse today than a "standard" 1013 day.
Surely the only relevant PA is that from Sea Level - so instead of the aerodrome being at 968ft on a "standard" day - today it now feels like it is 1,598 ft = therefore less performance, longer take off run etc.
Now I'll confuse the issue. I tried to work it out backwards. What is the QFE of this aerodrome on a standard day? Well 968ft / 30 = 32mb. So on a standard day of QNH 1013mb, QFE would be 1013-32=981mb. But today it is 992mb which is a HIGHER pressure reading, and therefore should provide BETTER performance - so why are Bose-x (1,598ft vs 968ft) and Islander2 (630ft vs 0ft) both showing worse performance. Where have I gone wrong?