An updated perspective on basin-scale tomography

There seems to be little doubt that pulse-like acoustic transmissions at 10 00 to 5000 km can be used to measure small changes in average temperature i n many oceanic regions, given the numerous results published by different g roups. The early experimental results in this field which led to these conc lusions have been confirmed by recent experiments. Our purpose in this Lett er is to summarize the work in this field in the context of addressing a fe w reservations expressed about the early experiments. (C) 2001 Acoustical S ociety of America.