Variación estacional del balance geostrófico en la región ecuatorial
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Abstract
Using hydrographic data gathered during the "NORPAX Hawaii-Tahiti Shuttle" (Feb. 1979- Jun. 1980) the seasonal variability of the geostrophic current field in a region of the central Pacific Ocean is studied. The study area includes the equator and its neighborhood, where the validity of the geostrophic balance is still a matter of controversy. With poten tia! energy as a metric, the isopycnal vertical displacement field is decomposed into empirical ortogonal functions. Most of the energy (92°/o) is found to be contained in the first three modes. The structure of the first mode (85°/0 of the energy) corresponds to that of the temporal average, whereas the second and third modes clearly show the existence of an annual signa! which contains 48°tb of the variability, that is, of the remaining 15otb. Position, magnitud and direction of the currents obtained using only these three modes, as well as their seasonal variations, agree very well with the results of other studies. The differences between the geostrophic currents and those directly measured are not found to be significant for both the mean and the anual fluctuations.
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References
CANTOS-FIGUEROLA, A. and B. A. TAFT, 1983. The South Equatorial Current during the 1979-80 Hawaii-Tahiti Shuttle. Tropical Newsletter, 19, (Manuscrito sin publicar).
CARRASCO, A. C., 1985. In certeza en el cálculo de corrientes geostróficas en una sección a lo largo de 110°W en febrero de 1979. Tesis Profesional. Universidad Autónoma de Baja California, Escuela Superior de Ciencias Marinas. 72 pp.
CUTCHIN, D. L., 1982. Data Shuttle Experiment, UCSD-SIO Ref. #82-20. 23 pp.
FREITAG, H. P. and E. FIRING, 1984. Comparison of profiling and moored current measurements in the Equatorial Pacific. J. Geophys. Res., 89, 3724-3728. DOI: https://doi.org/10.1029/JC089iC03p03724
HALPERN, D., R. A. WELLER, M. G. BRISCOE, R. E. DAVIS and J. R. McCULLOUGH, 1981. Intercomparison test of moored current measurements in the upper ocean. J. Geophys. Res. 86, 419-428. DOI: https://doi.org/10.1029/JC086iC01p00419
HAYES, S. P., 1982. A comparison of geostrophic and measured velocities in the Equatorial Undercurrent. J. Marine Res., 40 (Suppl.), 219-229.
HAYES, S. P., J. M. TOOLE and L. J. MANGUM, 1983. Water-mass and transport variability in the Equatorial Pacific. J. Phys. Ocean., 13, 153-168. DOI: https://doi.org/10.1175/1520-0485(1983)013<0153:WMATVA>2.0.CO;2
HIDAKA, K., 1955. Dynamical computation of ocean currents in a vertical section occupied across the Equator. Jap. J. Geophys., 1, 57-60.
JERLOV, N. G., 1953. Studies of the equatorial currents in the Pacific. Tellus, 5, 308-314. DOI: https://doi.org/10.1111/j.2153-3490.1953.tb01060.x
KNAUSS, J. A., 1960. Measurements of the Cromwell Current. Deep-Sea Res., 6, 265-286. DOI: https://doi.org/10.1016/0146-6313(59)90086-3
KNAUSS, J. A., 1966. Further measurements and observations on the Cromwell Current. J. Mar. Res., 24, 205-240.
LEETMAA, A. and R. L. MOLINARI, 1984. The cross-equatorial sections at 110°W. J. Phys. Ocean, 14, 255-263. DOI: https://doi.org/10.1175/1520-0485(1984)014<0255:TCESA>2.0.CO;2
LUKAS, R. and E. FIRING, 1983. The geostrophic balance of the Pacific Equatorial Undercurrent. Deep-Sea Res., 31, 61-66. DOI: https://doi.org/10.1016/0198-0149(84)90072-4
NAVA, C., 1982. Campos de densidad y velocidad geostrófica en el Océano Pacífico Ecuatorial. Tesis de maestría, Centro de Investigación Científica y de Educación Superior de Ensenada, Ensenada, B. C., Mex., 96 pp.
PATZERT, W. C., 1969. Eddies in Hawaiian waters. University of Hawaii, Rep. HIG-69-8, 50 pp.
RIPA, P., 1981. Symmetries and conservation laws for internal gravity waves. pp. 281-386, in: Nonlinear properties of internal waves (B. West, Ed.). A. I. P. Proceedings, New York. DOI: https://doi.org/10.1063/1.33180
TSUCHIYA, M., 1955. On a simple method of estimating the current velocity at the Equator. J. Ocean. Soc. Japan, 11, 1-4. DOI: https://doi.org/10.5928/kaiyou1942.11.1
WYRTKI, K., 1974. Equatorial currents in the Pacific from 1950 to 1970 and their relations to trade winds. J. Phys. Ocean. 4, 372-380. DOI: https://doi.org/10.1175/1520-0485(1974)004<0372:ECITPT>2.0.CO;2
WYRTKI, K., 1982a. An attempt to monitor the Equatorial Undercurrent. J. Geophys. Res., 88, 775-777. DOI: https://doi.org/10.1029/JC088iC01p00775
WYRTKI, K., 1982b. Eddies in the Pacific North Equatorial Current. J. Phys. Ocean., 12, 746-749. DOI: https://doi.org/10.1175/1520-0485(1982)012<0746:EITPNE>2.0.CO;2
WYRTKI, K., D. HALPERN, R. KNOX, G. J. McNALLY, W. C. PATZERT, E. D. STROUP, B. A. TAFT and R. WILLIAMS, 1981. The Hawaii to Tahiti Shuttle Experiment. Science, 211, 22-28. DOI: https://doi.org/10.1126/science.211.4477.22
WYRTKI, K. and R. KENDALL, 1967. Transports of the Pacific Equatorial Counter-currents. J. Geophys. Res., 72, 2073-2076. DOI: https://doi.org/10.1029/JZ072i008p02073
WYRTKI, K. and B. KILONSKY, 1984. Mean water and current structure during the Hawaii-to-Tahiti Shuttle Experiment. J. Phys. Ocean., 14, 242-214. DOI: https://doi.org/10.1175/1520-0485(1984)014<0242:MWACSD>2.0.CO;2