HR: 1340h
AN: OS13A-1012    [Abstracts]
TI: Surface Wind Speed from Deep-Ocean Acoustic Levels
AU: * Duennebier, F
EM: fred@soest.hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, University of Hawaii, Honolulu, HI 96822, United States
AU: Lukas, R
EM: nosal@hawaii.edu
AF: Oceanography Dept., SOES, University of HAwaii, Honolulu, HI 96822, United States
AU: Nosal, E
EM: nosal@hawaii.edu
AF: Dept. of Geology and Geophysics, SOEST, University of Hawaii, Honolulu, HI 96822, United States
AB: The ALOHA Cabled Observatory (ACO) is located about 100 km north of Oahu, Hawaii. Comparison of surface wind speeds measured at the WHOTS buoy at Station ALOHA with acoustic levels measured at the ACO on the ocean floor 4780 m below reveals strong correlation between surface wind speed and acoustic levels in several frequency bands. Characteristics of the acoustic spectra suggest that at least three different mechanisms are involved in the transfer of wind energy to the ocean floor. Characteristics of data in at least one of these bands, between 0.5 and 5 Hz, are not predicted by current theories. The correlation of surface winds with acoustic levels has been reported previously from other regions, but in this paper we analyze data acoustic from 0.03 Hz to 12 kHz and correlate it with WHOTS wind speeds between 2 and 10.5 m/s, limited by the range of observed wind speeds. Acoustic levels lag the wind speeds by 0 to 10 hours and saturation of the acoustic levels in some frequency bands implies a related correlation with the wind wave spectrum. Transient signals unrelated to wind speed add noise to the correlation, but since different transients are observed in different frequency bands, they can be removed from the signal. The strong correlations imply that recorded acoustic levels can be used as a proxy for surface wind speeds in historical data. The ACO was installed at Station ALOHA in mid February 2007, utilizing the retired HAW-4 commercial electro- optical telecommunications cable. The initial installation involved cutting the cable, moving it to Station ALOHA, splicing on a termination, and lowering it to the ocean floor with a set of preliminary sensors consisting of a broadband hydrophone and pressure sensor. The full observatory infrastructure will be installed in November 2007, using the JASON ROV. At that time, the infrastructure will be available to service up to eight sensor systems with about 100 W of continuous electrical power and a continuous 10 Base-T Ethernet link for each sensor system, expandable to 4-times that capacity as required.
UR: http://www.soest.hawaii.edu/GG/DeepoceanOBS/
DE: 3050 Ocean observatories and experiments
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4247 Marine meteorology
DE: 4259 Ocean acoustics
DE: 4504 Air/sea interactions (0312, 3339)
SC: Ocean Sciences [OS]
MN: 2007 Fall Meeting