ā
ā marks an animate agent of ñi. In the current sentence:
il ñamma anūri nā ā mūrāna masīrien
il ñamma jalūra rā sāen āñ nō ā marāona;
we have two agents. The agent of the first clause is mūrāna masīrien, the North Wind. The agent of the second clause is marāona, the wanderer. In both cases ñi is inflected for a 3rd person singular agent. So we have:
happening at the same time:
the North Wind causing/doing something
the wanderer causing/doing something