- Open Access
Detecting horizontal gradient of sound speed in ocean
Earth, Planets and Space volume 59, pages e33–e36 (2007)
We propose a new approach to monitor the horizontal gradient of sound speed in ocean for its correction on seafloor positioning using the GPS/acoustic technique. The new method requires five seafloor transponders to solve five parameters: δx, horizontal position of a transponder array; δt, a common delay in traveltimes due to the stratified component of sound speed; ∇t, the gradient of traveltime delays among the transponders associated with the sound speed gradient. We also numerically evaluate the geometrical strength of the five transponders’ layout and observation point to avoid possible trade-off among the parameters.
Chadwell, C. D. and F. N. Spiess, Plate motion at the ridge-transform boundary of the south Cleft segment of the Juan de Fuca Ridge from GPS-Acoustic data, J. Geophys. Res., 2007 (submitted).
Fujita, M., T. Ishikawa, M. Mochizuki, M. Sato, S. Toyama, M. Katayama, K. Kawai, Y. Matsumoto, T. Yabuki, A. Asada, and O. L. Colombo, GPS/Acoustic seafloor geodetic observation: method of data analysis and its application, Earth Planets Space, 58, 265–275, 2006.
Gagnon, K., C. D. Chadwell, and E. Norabuena, Measuring the onset of locking in the Peru-Chile trench with GPS and acoustic measurements, Nature, 434, 205–208, 2005.
Golub, G. H. and C. F. Van Loan, in Matrix Computations (3rd ed.), Johns Hopkins University Press, Baltimore, MD, 694 pp., 1996.
Holbrook, W. S. and I. Fer, Ocean internal wave spectra inferred from seismic reflection transects, Geophys. Res. Lett., 32, doi:10.1029/2005GL 023733, 2005.
Kawaguchi, K., E. Araki, and Y. Kaneda, A design concept of seafloor observatory network for earthquakes and tsunamis, abstract in International Symposium on Underwater Technology 2007, Tokyo, 176–178, 2007.
Kido, M., H. Fujimoto, S. Miura, Y. Osada, K. Tsuka, and T. Tabei, Seafloor displacement at Kumano-nada caused by the 2004 off Kii Peninsula earthquakes, detected through repeated GPS/Acoustic surveys, Earth Planets Space, 58, 911–915, 2006a.
Kido, M., Y. Osada, and H. Fujimoto, On the relation of radially-averaged sound velocities in seawater, measured with XBT and estimated in acoustic ranging, abstract for 106th Meeting of the Geodetic Society of Japan, 2006b (in Japanese).
Matsumoto, Y., M. Fujita, T. Ishikawa, M. Mochizuki, T. Yabuki, and A. Asada, Undersea co-seismic crustal movements associated with the 2005 Off Miyagi Prefecture Earthquake detected by GPS/acoustic seafloor geodetic observation, Earth Planets Space, 58, 1573–1576, 2006.
Munk, W., P. Worcester, and C. Wunsch, Ocean acoustic tomography, 447 pp., Cambridge Univ. Press, 1995.
Spiess, F. N., Analysis of a possible sea floor strain measurement system, Marine Geodesy, 9, 385–398, 1985.
Spiess, F. N., C. D. Chadwell, J. A. Hildebrand, L. E. Young, G. H. Pur-cell Jr., and H. Dragert, Precise GPS/Acoustic positioning of seafloor reference points for tectonic studies, Phys. Earth Planet. Inter., 108, 101–112, 1998.
Sugimoto, S., R. Ikuta, M. Ando, K. Tadokoro, T. Okuda, and G. M. Besana, Evaluation for GPS/Acoustic seafloor positioning based on repeated CTD measurements, Earth Planets Space, 2006 (submitted).
Tadokoro, K., M. Ando, R. Ikuta, T. Okuda, G. Besana, S. Sugimoto, and M. Kuno, Observation of coseismic seafloor crustal deformation due to M7 class offshore earthquakes, Geophys. Res. Lett., 33, doi:10.1029/2006GL026742, 2006.
About this article
Cite this article
Kido, M. Detecting horizontal gradient of sound speed in ocean. Earth Planet Sp 59, e33–e36 (2007). https://doi.org/10.1186/BF03352027
- GPS/Acoustic technique
- seafloor geodesy
- sound speed
- inverse problem