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Abstract
Two sources of H 1/3 estimates were available at Platform Harvest; a NOAA buoy and CU depth sensor highrate data. H 1/3 estimates from the NOAA buoy were based on 20 min of data every hour. CU pressure measurements were taken every 1.1 s. For purposes of this paper H 1/3 estimates from the CU depth sensor were based on 1 h of data. This paper compares H 1/3 measurements from TOPEX with each of these sources. Differences between H 1/3 estimates from the CU depth sensors based on 20 min and estimates based on 1 h of data varied by up to 10% with an rms uncertainty of ±5%. There is an rms difference between the NOAA buoy and altimeter values of 0.17 m with a mean offset of 0.03 m such that the H 1/3 values from the altimeter are higher than from the buoy. There is an rms difference between the CU values and altimeter values of 0.19 m with a mean offset of 0.1 m such that the H 1/3 values from the altimeter are higher than from the CU depth sensors. This strongly suggests that the H 1/3 measurements from the TOPEX altimeter are well within project specifications.