앙상블 경험적 모드 분해법을 사용한 태평양의 지역별 해수면 변화 분석
Regional Sea Level Variability in the Pacific during the Altimetry Era Using Ensemble Empirical Mode Decomposition Method
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참고문헌
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초록
Natural variability associated with a variety of large-scale climate modes causes regional differences in sea level rise (SLR), which is particularly remarkable in the Pacific Ocean. Because the superposition of the natural variability and the background anthropogenic trend in sea level can potentially threaten to inundate low-lying and heavily populated coastal regions, it is important to quantify sea level variability associated with internal climate variability and understand their interaction when projecting future SLR impacts. This study seeks to identify the dominant modes of sea level variability in the tropical Pacific and quantify how these modes contribute to regional sea level changes, particularly on the two strong El Niño events that occurred in the winter of 1997/1998 and 2015/2016. To do so, an adaptive data analysis approach, Ensemble Empirical Mode Decomposition (EEMD), was undertaken with regard to two datasets of altimetry-based and in situ-based steric sea levels. Using this EEMD analysis, we identified distinct internal modes associated with El Niño-Southern Oscillation (ENSO) varying from 1.5 to 7 years and low-frequency variability with a period of ~12 years that were clearly distinct from the secular trend. The ENSO-scale frequencies strongly impact on an east-west dipole of sea levels across the tropical Pacific, while the low-frequency (i.e., decadal) mode is predominant in the North Pacific with a horseshoe shape connecting tropical and extratropical sea levels. Of particular interest is that the low-frequency mode resulted in different responses in regional SLR to ENSO events. The low-frequency mode contributed to a sharp increase (decrease) of sea level in the eastern (western) tropical Pacific in the 2015/2016 El Niño but made a negative contribution to the sea level signals in the 1997/1998 El Niño. This indicates that the SLR signals of the ENSO can be amplified or depressed at times of transition in the low-frequency mode in the tropical Pacific.
Abstract
Natural variability associated with a variety of large-scale climate modes causes regional differences in sea level rise (SLR), which is particularly remarkable in the Pacific Ocean. Because the superposition of the natural variability and the background anthropogenic trend in sea level can potentially threaten to inundate low-lying and heavily populated coastal regions, it is important to quantify sea level variability associated with internal climate variability and understand their interaction when projecting future SLR impacts. This study seeks to identify the dominant modes of sea level variability in the tropical Pacific and quantify how these modes contribute to regional sea level changes, particularly on the two strong El Niño events that occurred in the winter of 1997/1998 and 2015/2016. To do so, an adaptive data analysis approach, Ensemble Empirical Mode Decomposition (EEMD), was undertaken with regard to two datasets of altimetry-based and in situ-based steric sea levels. Using this EEMD analysis, we identified distinct internal modes associated with El Niño-Southern Oscillation (ENSO) varying from 1.5 to 7 years and low-frequency variability with a period of ~12 years that were clearly distinct from the secular trend. The ENSO-scale frequencies strongly impact on an east-west dipole of sea levels across the tropical Pacific, while the low-frequency (i.e., decadal) mode is predominant in the North Pacific with a horseshoe shape connecting tropical and extratropical sea levels. Of particular interest is that the low-frequency mode resulted in different responses in regional SLR to ENSO events. The low-frequency mode contributed to a sharp increase (decrease) of sea level in the eastern (western) tropical Pacific in the 2015/2016 El Niño but made a negative contribution to the sea level signals in the 1997/1998 El Niño. This indicates that the SLR signals of the ENSO can be amplified or depressed at times of transition in the low-frequency mode in the tropical Pacific.
참고문헌 (30)
- Ablain M, "A new assessment of global mean sea level from altimeters highlights a reduction of global trend from 2005 to 2008", Ocean Sci Disc, 6(1), pp.31~56 (2009)
- Beckley BD, "Assessment of the Jason-2 extension to the TOPEX", Poseidon, Jason-1 sea-surface height time series for global mean sea level monitoring, 2010, pp.33(S1), 447~471
- Peter D. Bromirski, "Dynamical suppression of sea level rise along the Pacific coast of North America: Indications for imminent acceleration", Journal of Geophysical Research, 116(C7), pp.JC006759~ (2011), American Geophysical Union (AGU)[DOI]
- 차상철, "위성 고도계와 해수면 재구성 자료를 이용한 기후변동성에 따른 태평양 해수면 변화", Ocean and Polar Research, 40(1), pp.1~13 (2018), 한국해양과학기술원[DOI]
- Cha SC, "A recent shift toward an El Niño-like ocean state in the Tropical Pacific and the resumption of ocean warming", Geophys Res Lett, 45(21), pp.11885~11894 (2018)
- Church JA, "Understanding sea-level rise and variability", pp.402~419 (2010), Blackwell
- Church JA, "Sea-level rise from the late 19th to the early 21st century", Surv Geophys, 32(4−5), pp.585~602 (2011)
- Good SA, "EN4: quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates", J Geophys Res-Oceans, 118(12), pp.6704~6716 (2013)
- Hamlington BD, "Uncovering an anthropogenic sealevel rise signal in the Pacific Ocean", Nat Clim Change, 4(9), pp.782~785 (2014)
- Hamlington BD, "An ongoing shift in Pacific Ocean sea level", J Geophys Res-Oceans, 121(7), pp.5084~5097 (2016)
- Hu S, "The extreme El Niño of 2015−2016: the role of westerly and easterly wind bursts, and preconditioning by the failed 2014 event", Clim Dynam, 52(12), pp.7339~7357 (2017)
- Huang NE, "The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis", P Roy Soc AMath Phy, 454(1971), pp.903~995 (1998)
- Kidwell A, "A closer look at the central Pacific El Niño and warm pool migration events from 1982 to 2011", J Geophys Res-Oceans, 119(1), pp.165~172 (2014)
- Kim Y, "Sea level rise around Korea: analysis of tide gauge station data with the ensemble empirical mode decomposition method", J Hydro-Environ Res, 11, pp.138~145 (2016)
- Felix W. Landerer, "El Niño−Southern Oscillation signals in sea level, surface mass redistribution, and degree-two geoid coefficients", Journal of Geophysical Research, 113(C8), pp.JC004767~ (2008), American Geophysical Union (AGU)[DOI]
- Lee HS, "Multi-decadal variations of ENSO, the Pacific Decadal Oscillation and tropical cyclones in the western North Pacific", Prog Oceanogr, 105, pp.67~80 (2012)
- Lei Y, "Application of the EEMD method to rotor fault diagnosis of rotating machinery", Mech Syst Signal Pr, 23(4), pp.1327~1338 (2009)
- Leuliette EW, "Integrating Jason-2 into a multiple-altimeter climate data record", Mar Geod, 33(S1), pp.504~517 (2010)
- Levine AF, "How the July 2014 easterly wind burst gave the 2015−2016 El Niño a head start", Geophys Res Lett, 43(12), pp.6503~6510 (2016)
- Mantua NJ, "A Pacific interdecadal climate oscillation with impacts on salmon production", B Am Meteorol Soc, 78(6), pp.1069~1080 (1997)
- Masters D, "Comparison of global mean sea level time series from TOPEX", Poseidon, Jason-1, and Jason-2, 2012, pp.35(S1), 20~41
- Merrifield MA, "A shift in western tropical Pacific sea level trends during the 1990s", J Climate, 24(15), pp.4126~4138 (2011)
- Mark A. Merrifield, "Multidecadal sea level anomalies and trends in the western tropical Pacific", Geophysical Research Letters, 39(13), pp.GL052032~ (2012), American Geophysical Union (AGU)[DOI]
- Moon JH, "Multidecadal regional sea level shifts in the Pacific over 1958−2008", J Geophys Res-Oceans, 118(12), pp.7024~7035 (2013)
- Moon JH, "PDO and ENSO modulations intensified decadal sea level variability in the tropical Pacific", J Geophys Res-Oceans, 120(12), pp.8229~8237 (2015)
- Nerem RS, "Estimating mean sea level change from the TOPEX and Jason altimeter missions", Mar Geod, 33(S1), pp.435~446 (2010)
- Wu Z, "A study of the characteristics of white noise using the empirical mode decomposition method", P Roy Soc A-Math Phy, 460(2046), pp.1597~1611 (2004)
- Wu Z, "Ensemble empirical mode decomposition: a noise-assisted data analysis method", Adv Adapt Data Anal, 1(1), pp.1~41 (2009)
- Yeo SR, "The role of lowfrequency variation in the manifestation of warming trend and ENSO amplitude", Clim Dynam, 49(4), pp.1197~1213 (2017)
- Xuebin Zhang, "Sea level trends, interannual and decadal variability in the Pacific Ocean", Geophysical Research Letters, 39(21), pp.GL053240~ (2012), American Geophysical Union (AGU)[DOI]