Ar_T = 0. _d 0
Ar_T = Ar_T + Ar
_GLOBAL_SUM_RL( Ar_T , myThid )
IF ( Ar_T .GT. 0. _d 0 ) THEN
Tr_T = (0. _d 0 - Tr_T)/Ar_T
_RL Tr_T, Ar_T, Ar