check existence of items within a state

ESMF_StateGet() can be used to check the existence of items (without raising an ESMF error in case of non-existing items):

type(ESMF_StateItem_Flag) :: itemType
call ESMF_StateGet(state, name, itemType)
if (itemType .eq. ESMF_STATEITEM_NOTFOUND) then

For more details see:
http://www.earthsystemmodeling.org/esmf_releases/public/last/ESMF_refdoc/node4.html#SECTION04077900000000000000