Gian Luca Eusebi Borzelli
Center for Remote Sensing of the Earth (CERSE), Rome, 00153, Italy
Arnold Sullivan
CSIRO, Environment, Aspendale, 3195, Australia
School of Earth, Atmosphere, and Environment, Monash University, Melbourne, 3800, Australia
Internal Kelvin Wave (KW) propagation is studied about variations in the sea surface temperature anomaly (SSTA) over the tropical Pacific. Temperature and Salinity (TS) observations have been used to define the vertical structure of the ocean about the propagation properties of KWs. Changes in the vertical structure of the water column determine consistent zonal variations in the wave velocity, with values varying, roughly, from 1.8 to 2.6 m/s. The authors document that KWs are formed regularly at the western boundary of the tropical Pacific, but, in these cases, never overcome the dateline. Occasionally, KWs are generated in the region comprised between 170oE and 170oW, and, on all these occasions, a positive phase of the El Niño Southern Oscillation (El Niño) event is recorded. A model, named Sloping Interface Model (SIM), is proposed to relate changes in the pycnocline depth, associated with transiting KWs, and SST anomaly variations. In the SIM, whose equations are consistent with the Recharge/Discharge paradigm, the ocean is described as a two-layer system and the climatological state, represented by a sloping pycnocline, is maintained by a constant easterly wind stress. Using the SIM and coherently with the Recharge/Discharge paradigm, the authors show that changes in the averaged SSTA over El Niño 3, 3.4 and 4 regions are nearly perfectly correlated to pycnocline displacements due to transiting KWs.
[1] Bjerknes, J., 1969. Atmospheric teleconnections from the equatorial Pacific. Monthly Weather Review. 97(3), 163–172. DOI: https://doi.org/10.1175/1520-0493(1969)097<0163:ATFTEP>2.3.CO;2
[2] Wyrtki, K., 1975. El Niño—the dynamic response of the equatorial Pacific Oceanto atmospheric forcing. Journal of Physical Oceanography. 5(4), 572–584. DOI: https://doi.org/10.1175/1520-0485(1975)005<0572:ENTDRO>2.0.CO;2
[3] Rasmusson, E.M., Wang, X., Ropelewski, C.F., 1990. The biennial component of ENSO variability. Journal of Marine Systems. 1(1–2), 71–96. DOI: https://doi.org/10.1016/0924-7963(90)90153-2
[4] Jiang, N., Neelin, J.D., Ghil, M., 1995. Quasi-quadrennial and quasi-biennial variability in the equatorial Pacific. Climate Dynamics. 12, 101–112. DOI: https://doi.org/10.1007/BF00223723
[5] Torrence, C., Compo, G.P., 1998. A practical guide to wavelet analysis. Bulletin of the American Meteorological Society. 79(1), 61–78. DOI: https://doi.org/10.1175/1520-0477(1998)079<0061:APGTWA>2.0.CO;2
[6] Philander, S.G., 1990. El Nino, La Nina and the southern oscillation. Academic Press: New York.
[7] Jin, F.F., 1997. An equatorial ocean recharge paradigm for ENSO. Part I: Conceptual model. Journal of the Atmospheric Sciences. 54(7), 811–829. DOI: https://doi.org/10.1175/1520-0469(1997)054<0811:AEORPF>2.0.CO;2
[8] Jin, F.F., 1997. An equatorial ocean recharge paradigm for ENSO. Part II: A stripped-down coupled model. Journal of the Atmospheric Sciences. 54(7), 830–847. DOI: https://doi.org/10.1175/1520-0469(1997)054<0830:AEORPF>2.0.CO;2
[9] Chen, D., Cane, M.A., Kaplan, A., et al., 2004. Predictability of El Niño over the past 148 years. Nature. 428, 733–736. DOI: https://doi.org/10.1038/nature02439
[10] Chen, D., Cane, M.A., 2008. El Niño prediction and predictability. Journal of Computational Physics. 227(7), 3625–3640. DOI: https://doi.org/10.1016/j.jcp.2007.05.014
[11] Suarez, M.J., Schopf, P.S., 1988. A delayed action oscillator for ENSO. Journal of the Atmospheric Sciences. 45(21), 3283–3287. DOI: https://doi.org/10.1175/1520-0469(1988)045<3283:ADAOFE>2.0.CO;2
[12] Battisti, D.S., Hirst, A.C., 1989. Interannual variability in a tropical atmosphere-ocean model: Influence of the basic state, ocean geometry and nonlinearity. Journal of the Atmospheric Sciences. 46(12), 1687–1712. DOI: https://doi.org/10.1175/1520-0469(1989)046<1687:IVIATA>2.0.CO;2
[13] Picaut, J., Delcroix, T., 1995. Equatorial wave sequence associated with warm pool displacements during the 1986–1989 El Niño‐La Niña. Journal of Geophysical Research. 100(C9), 18393–18408. DOI: https://doi.org/10.1029/95JC01358
[14] Fedorov, A.V., Harper, S.L., Phiander, G., et al., 2003. How predictable is El Niño? Bulletin of the American Meteorological Society. 84(7), 911–920. DOI: https://doi.org/10.1175/BAMS-84-7-911
[15] Arora, A., 2022. The effect of the variability of wind forcing on ENSO simulation in an OGCM: case of canonical and protracted event. Theoretical and Applied Climatology. 147, 265–281. DOI: https://doi.org/10.1007/s00704-021-03816-5
[16] Arora, A., Kumar, S., 2019. What makes protracted El Niño to last longer than canonical El Niño? Theoretical and Applied Climatology. 136, 587–603. DOI: https://doi.org/10.1007/s00704-018-2503-8
[17] Wang, C., Fiedler, P.C., 2006. ENSO variability and the eastern tropical pacific: A review. Progress in Oceanography. 69(2–4), 239–266. DOI: https://doi.org/10.1016/j.pocean.2006.03.004
[18] Santoso, A., Mcphaden, M.J., Cai, W. 2017. The defining characteristics of ENSO extremes and the strong 2015/2016 El Niño. Reviews of Geophysics. 55(4), 1079–1129. DOI: https://doi.org/10.1002/2017RG000560
[19] Kang, I.S., An, S.I., 1998. Kelvin and Rossby wave contributions to the SST oscillation of ENSO. Journal of Climate. 11(9), 2461–2469. DOI: https://doi.org/10.1175/1520-0442(1998)011<2461:KARWCT>2.0.CO;2
[20] Eusebi Borzelli, G.L., Carniel, S., 2023. Where the winds clash: What is really triggering El Niño initiation?. npj Climate and Atmospheric Science. 6, 119. DOI: https://doi.org/10.1038/s41612-023-00445-9
[21] Yang, J., Yu, L., 1992. Propagation of equatorially trapped waves on a sloping thermocline. Journal of Physical Oceanography. 22(6), 573–582. DOI: https://doi.org/10.1175/1520-0485(1992)022<0573:POETWO>2.0.CO;2
[22] Burger, G., Jin, F.F., 2005. The simplest ENSO recharge oscillator. Geophysical Research Letters. 32(13). DOI: https://doi.org/10.1029/2005GL022951
[23] Boulanger, J.P., Menkes, C., 1995. Propagation and reflection of long equatorial waves in the Pacific Ocean during the 1992–1993 El Nino. Journal of Geophysical Research. 100(C12), 25041–25059. DOI: https://doi.org/10.1029/95JC02956
[24] Boulanger, J.P., Menkes, C., 1999. Long equatorial wave reflection in the Pacific Ocean from TOPEX/POSEIDON data during the 1992–1998 period. Climate Dynamics. 15, 205–225. DOI: https://doi.org/10.1007/s003820050277
[25] Boulanger, J.P., Cravatte, S., Menkes, C., 2003. Reflected and locally wind‐forced interannual equatorial Kelvin waves in the western Pacific Ocean. Journal of Geophysical Research. 108(C10). DOI: https://doi.org/10.1029/2002JC001760
[26] Gill, A.E., 1982. Atmosphere-ocean dynamics. Academic Press: Cambridge.
[27] Fidler, P.C., Mendelssohn, R., Palacios, D.M., et al., 2013. Pycnocline variations in the eastern tropical and north pacific, 1958–2008. Journal of Climate. 26(2), 583–599. DOI: https://doi.org/10.1175/JCLI-D-11-00728.1
[28] Zebiak, S.E., Cane, M.A., 1987. A model El Niño–Southern oscillation. Monthly Weather Review. 115(10), 2262–2278. DOI: https://doi.org/10.1175/1520-0493(1987)115<2262:AMENO>2.0.CO;2
[29] Jaffrés, J.B.D., Cuff, C., Rasmussen, C., et al., 2018. Teleconnection of atmospheric and oceanic climate anomalies with Australian weather patterns: A review of data availability. Earth-Science Reviews. 176, 117–146. DOI: https://doi.org/10.1016/j.earscirev.2017.08.010
[30] Zhang, C., 2015. Climate and climate change | Global impacts of the Madden-Julian oscillation. Encyclopedia of atmospheric sciences (second edition). Academic Press: Cambridge. pp. 73–79. DOI: https://doi.org/10.1016/B978-0-12-382225-3.00510-7
[31] Sullivan, A., Zhong, W., Eusebi Borzelli, G.L., et al., 2021. Generation of westerly wind bursts by forcing outside the tropics. Scientific Reports. 11, 912. DOI: https://doi.org/10.1038/s41598-020-79655-7
[32] Wunsch, C., 1998. The work done by the wind on the oceanic general circulation. Journal of Physical Oceanography. 28(11), 2332–2340. DOI: https://doi.org/10.1175/1520-0485(1998)028<2332:TWDBTW>2.0.CO;2
Copyright © 2024 Gian Luca Eusebi Borzelli, Arnold Sullivan
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