Twice daily low-passed filtered time-series data from inverted echo sounders for the Hawaii Ocean Time Series (HOT) project north of Oahu, Hawaii from 19910201 to 19980715 (NODC Accession 9900215)

The HOT program makes repeated observations of the physics, biology and chemistry at a site approximately 100 km north of Oahu, Hawaii. Two stations are visited about once a month: Kahe Point (Station 1: 21.34N, 158.27W) and Station ALOHA (Station 2: 22.75N, 158W). Various other stations are made intermittently in support of similar research objectives or mooring deployments. In 1991, a 50-km array of 5 inverted echo sounders (IESs) was deployed as part of the WOCE deep water station. IESs record the round-trip acoustic travel time from the sea floor to the sea surface, which is known to correlate well with dynamic height. CTD casts made during 25 monthly cruises to the deep-water station were used to calibrate the IES. The conversion factor from travel time to dynamic height was found to be -54 dyn m/s. The time-series from the IESs show that there are many fluctuations in dynamic height having timescales from weeks to months that are not well resolved with the CTD sampling.