Journal of the Korean earth science society (한국지구과학회지)

The Korean Earth Science Society (한국지구과학회)
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Roles of Wind Stress Variations in the Western North Pacific on the Decadal Change of ENSO

ENSO 십년 변동에 미치는 북서태평양 지역에서의 바람 응력 변동의 역할

  • Lee, Yoon-Kyoung (School of Earth and Environmental Sciences, Seoul National University) ;
  • Moon, Byung-Kwon (Division of Science Education/Institute of Science Education, Chonbuk National University) ;
  • Kwon, Min-Ho (The Research Institute of Basic Sciences, Seoul National University) ;
  • Jhun, Jong-Ghap (School of Earth and Environmental Sciences, Seoul National University)
  • 이윤경 (서울대학교 지구환경과학부) ;
  • 문병권 (전북대학교 과학교육학부/과학교육 연구소) ;
  • 권민호 (서울대학교 기초과학연구원) ;
  • 전종갑 (서울대학교 지구환경과학부)
  • Published : 2006.12.30
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Abstract

This paper investigated the effects of wind stress forcing in the western North Pacific on ENSO decadal change before and after the late 1970s. The SVD analysis of SODA data shows that a positive wind stress curl is dominant in the western North Pacific at the ENSO mature phase, which leads to the ENSO phase change by discharge/recharge heat contents in the equatorial Pacific. Before the late 1970s, the wind stress curl in the western North Pacific was strong. This strong wind forcing that is associated with the fast discharge of heat contents in the equator led to the short period and the weak intensity of ENSO occurred during the 1960-1970. On the other hand, after the late 1970s the relatively weak wind stress curl was accompanied with the long period and the strong intensity of ENSO. The simple coupled model experiments also confirm that the amplitude and dominant period of ENSO decrease when the wind stress curl in the western North Pacific projects more strongly into the ocean at the TNSO mature phase. Our results support that the changes in the behavior of ENSO after the late 1970s are associated with the wind stress variation in the western North Pacific.

북서태평양의 바람 변동이 1970년대 이후에 나타난 ENSO의 십년 주기 변화에 미치는 영향을 조사하였다. SODA 자료를 이용한 SVD 분석을 통하여 ENSO 절정기에 북서태평양에서 나타나는 양의 바람 응력 컬이 적도 지역에서의 열함유량을 방출/재충전(discharge/recharge)시켜 ENSO의 위상을 변화시킨다는 것을 보였다. ENSO와 연관된 북서태평양의 바람 응력 컬은 1970년대 이전에 강하게 나타났다. 이러한 강한 바람 응력 강제력은 적도의 열함유량을 빠르게 방출시켰고, 결과로서 1960-1970년대 기간 동안에 ENSO의 주기가 짧고 강도가 악하게 나타났다 반면에 1970년대 후반 이후에는 북서태평양 바람 응력의 컬이 약해지면서 ENSO의 주기가 길어지고 강도가 강해졌다. 간단한 대기-해양 접합 모델 실험으로 관측 자료 분석 결과와 유사하게 북서태평양 지역에서 바람 응력 컬이 더 많이 해양에 작용할 때 ENSO의 진폭과 주기가 감소하는 것을 보였다. 이 결과들은 1970년대 후반 이후에 나타난 ENSO특징의 변화가 북서태평양 지역에서의 바람 응력의 변화와 관련이 있다는 것을 제시한다.

Keywords

References

  1. An, S.-I. and Kang, I.-S., 2001, Tropical Pacific basin-wide adjustment and oceanic waves. Geophysical Research Letters, 28, 3975-3978 https://doi.org/10.1029/2001GL013363
  2. An, S.-I. and Wang, B., 2000, Interdecadal change of the structure of the ENSO mode and its impact on the ENSO frequency. Journal of Climate, 13, 2044-2055 https://doi.org/10.1175/1520-0442(2000)013<2044:ICOTSO>2.0.CO;2
  3. Bjerknes, J., 1969, Atmospheric teleconnections from the equatorial Pacific. Monthly Weather Review, 97, 163- 172 https://doi.org/10.1175/1520-0493(1969)097<0163:ATFTEP>2.3.CO;2
  4. Bretherton, C.S., Smith, C., and Wallace, J.M., 1992, An intercomparison of methods for finding coupled patterns in climate data. Journal of Climate, 5, 541-560 https://doi.org/10.1175/1520-0442(1992)005<0541:AIOMFF>2.0.CO;2
  5. Carton, J., Chepurin, G., Cao, X., and Giese, B., 2000, A simple ocean data assimilation analysis of the global upper ocean 1950-1995, Part I: Methodology. Journal of Physical Oceanography, 30, 294-30 https://doi.org/10.1175/1520-0485(2000)030<0294:ASODAA>2.0.CO;2
  6. Cassou, C. and Perigaud, C., 2000, ENSO simulated by intermediate coupled models and evaluated with observations over 1970-98, Part II: Role of the off-equatorial ocean and meridional winds. Journal of Climate, 13, 1635-1663 https://doi.org/10.1175/1520-0442(2000)013<1635:ESBICM>2.0.CO;2
  7. Jin, F.-F., 1996, Tropical ocean-atmosphere interaction, the pacific cold tongue, and the El Nino Southern Oscillation. Science, 274, 76-78 https://doi.org/10.1126/science.274.5284.76
  8. Jin, F.-F., 1997, An equatorial ocean recharge paradigm for ENSO, Part I: Conceptual model. Journal of Atmospheric Society, 54, 811-829 https://doi.org/10.1175/1520-0469(1997)054<0811:AEORPF>2.0.CO;2
  9. Kang, I.-S. and Lau, K.-M., 1994, Principal modes of atmospheric circulation anomalies associated with global angular momentum fluctuations. Journal of Atmospheric Society, 51, 1194-1205 https://doi.org/10.1175/1520-0469(1994)051<1194:PMOACA>2.0.CO;2
  10. Kang, I.-S. and Kug, J.-S., 2000, An El-Nino prediction model with an intermediate ocean and statistical atmosphere system. Geophysical Research Letters, 27, 1167- 1170 https://doi.org/10.1029/1999GL011023
  11. Kang, I.-S. and Kug, J.-S., 2001, El Nino and La Nina SST anomalies: Asymmetry characteristics associated with their wind stress anomalies. China Meteorological Press, 621-634
  12. Kang, I.-S. and An, S.-I., 1998, Kelvin and Rossby wave contributions to the SST oscillation of ENSO. Journal of Climate, 11, 2461-2469 https://doi.org/10.1175/1520-0442(1998)011<2461:KARWCT>2.0.CO;2
  13. Kumar, K.K., Rajagopalan, B., and Cane, M.A., 1999, On the weakening relationship between the Indian Monsoon and ENSO. Science, 284, 2156-2159 https://doi.org/10.1126/science.284.5423.2156
  14. Latif, M. and Barnett, T.P., 1994, Causes of decadal climate variability over the North Pacific and North America sector. Science, 266, 634-637 https://doi.org/10.1126/science.266.5185.634
  15. Lighthill, M.J., 1969, Dynamical response of the Indian Ocean to onset of the southwest monsoon. Philosophical Transactions of the Royal Society of London, Series A, 265, 45-92 https://doi.org/10.1098/rsta.1969.0040
  16. Moon, B.-K., Yeh, S.-W., Dewitte, B., Jhun, J.-G., Kang, I.-S., and Kirtman, B.P., 2004, Vertical structure variability in the equatorial Pacific before and after the Pacific climate shift of the 1970s. Geophysical Research Letters, 31, L03203 https://doi.org/10.1029/2003GL018829
  17. Nitta, T. and Yamada, S., 1989, Recent warming of tropical sea surface temperature and its relationship to the Northern Hemisphere circulation. Journal of Meteorological Society of Japan, 67 (3), 375-383 https://doi.org/10.2151/jmsj1965.67.3_375
  18. Trenberth, K.E. and Hurrell, J.W., 1994, Decadal atmosphere- ocean variations in the Pacific. Climate Dynamics, 9, 303-319 https://doi.org/10.1007/BF00204745
  19. Wang, B., Wu, R., and Lau, K.-M., 2001, Interannual variability of the Asian summer Monsoon: Contrasts between the Indian and the Western North Pacific-East Asian Monsoon. Journal of Climate, 14, 4073-4090 https://doi.org/10.1175/1520-0442(2001)014<4073:IVOTAS>2.0.CO;2
  20. Wang, B., Wu, R., and Lukas, R., 1999, Roles of the western North Pacific wind variation in thermocline adjustment and ENSO phase transition. Journal of Meteorological Society of Japan, 77, 1-16 https://doi.org/10.2151/jmsj1965.77.1_1
  21. Wang, B. and An, S.-I., 2001, Why the properties of El Nino changed during the late 1970s. Geophysical Research Letters, 28, 3709-3712 https://doi.org/10.1029/2001GL012862
  22. Weisberg R.H. and Wang, C., 1997, A western Pacific oscillator paradigm for the El Nino-Southern Oscillation. Geophysical Research Letters, 24, 779-782 https://doi.org/10.1029/97GL00689
  23. Yeh, S.-W., Dewitte, B., Jhun, J.-G., and Kang, I.-S., 2001, The characteristic oscillation induced by coupled processes between oceanic vertical modes and atmospheric modes in the tropical Pacific. Geophysical Research Letters, 28, 2847-2850 https://doi.org/10.1029/2001GL012854
  24. Zebiak, S.E. and Cane, M.A., 1987, A model El Nino Southern Oscillation. Monthly Weather Review, 115, 2262-2278 https://doi.org/10.1175/1520-0493(1987)115<2262:AMENO>2.0.CO;2
  25. Zhang, R.-H. and Levitus, S., 1997, Structure and cycle of decadal variability of upper ocean temperature in the North Pacific. Journal of Climate, 10, 710-727 https://doi.org/10.1175/1520-0442(1997)010<0710:SACODV>2.0.CO;2