the arrival hall sections are all numbered. the best way to do this is to use cell phone / sms to communicate which number you are at, or to agree to a middle # ahead of time. (domestic arr at smaller numbers, maybe 10-14, intl maybe 15-20)

see terminal map link from here
http://www.shairport.com/en/airline03_a.jsp#

the dep level correspondence here
http://www.shairport.com/gb/images/shopfoodnav.gif