A comparison of acoustic thermometry, satellite altimetry, and other observations of ocean temperature in the North Pacific Ocean

• Main Authors: Peter F. Worcester, Brian D. Dushaw
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: New Zealand; Pacific; Kamchatka
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.116.6146; http://npal.ucsd.edu/publications/unrefereed_pubs/porsec2000.pdf

Acoustic thermometry gives integral measurements of large-scale ocean temperature, providing the spatial low-pass filtering needed to observe small, gyre-scale signals in the presence of much larger, mesoscale noise. Approximately two-year-long time series of temperature have been measured using long-range acoustic transmissions in the Northeast Pacific by the Acoustic Thermometry of Ocean Climate (ATOC) project. The signals transmitted by two sources, one on Pioneer Seamount off California and one north of Kauai, were received at various times by (i) U. S. Navy SOSUS arrays, (ii) vertical receiving arrays near the island of Hawaii, near Kiritimati (Christmas) Island, and at OWS Papa; (iii) a Russian receiver off Kamchatka; and (iv) a receiver off New Zealand. Temperature data from the Hawaiian Ocean Time-series (HOT) site show substantially more mesoscale noise than the integral acoustic data, as expected, although transmissions between Hawaii and California show a surprising amount of variability at roughly 100-day time scales. Assuming that variations in sea surface height are caused by thermal expansion in the upper 100 m of the ocean, the annual cycle of heat content derived from altimetry is larger than that derived from the acoustic data, from XBTs of opportunity, and from climatology. Consistent results for the seasonal heat storage in the ocean are found when the acoustic and altimetry data are combined with a computer model