Modulation of El Nino-Southern Oscillation by Freshwater Flux  and Salinity Variability in the Tropical Pacific

ZHANG Rong-Hua; ZHENG Fei; PEI Yuhua; ZHENG Quanan; WANG Zhanggui

doi:10.1007/s00376-012-1235-4

Impact Factor: 5.8

Volume 29 Issue 4

Jul. 2012

Article Contents

Article > ADVANCES IN ATMOSPHERIC SCIENCES > 2012 > 29(4): 647-660

Modulation of El Nino-Southern Oscillation by Freshwater Flux and Salinity Variability in the Tropical Pacific

1.
Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA;Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA, International Center for Climate and Environment Science, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA, The College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266003, State Key Laboratory of Satellite Ocean Environment Dyna;Department of Atmosphere and Ocean Science, University of Maryland, College Park, Maryland, USA;ational Marine Environmental Forecasting Center, State Oceanic Administration, Beijing 100081

doi: 10.1007/s00376-012-1235-4

Abstract
References
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Abstract:
The El Nino-Southern Oscillation (ENSO) is modulated by many factors; most previous studies have emphasized the roles of wind stress and heat flux in the tropical Pacific. Freshwater flux (FWF) is another environmental forcing to the ocean; its effect and the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model (HCM) to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity (SSS) and buoyancy flux (QB) in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual QB variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nina and enhancing warming during El Nino, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.
- freshwater flux (FWF) forcing and feedback,
- sea surface salinity (SSS) variability,
- ENSO modulation,
- coupled ocean-atmosphere models
References

[1]	Wu Aiming, Ni Yunqi, 1999: A Hybrid Coupled Ocean-Atmosphere Model and ENSO Prediction Study, ADVANCES IN ATMOSPHERIC SCIENCES, 16, 405-418. doi: 10.1007/s00376-999-0019-y
[2]	Yu Yongqiang, Guo Yufu, 1995: The Interannual Variability of Climate in a Coupled Ocean-Atmosphere Model, ADVANCES IN ATMOSPHERIC SCIENCES, 12, 273-288. doi: 10.1007/BF02656977
[3]	Junya HU, Rong-Hua ZHANG, Chuan GAO, 2019: A Hybrid Coupled Ocean-Atmosphere Model and Its Simulation of ENSO and Atmospheric Responses, ADVANCES IN ATMOSPHERIC SCIENCES, 36, 643-657. doi: 10.1007/s00376-019-8197-8
[4]	Zhong Qing, Ji Liren, 1992: A Further Study on an Extended Nonlinear Ocean-Atmosphere Coupled Hydrodynamic Characteristic System and the Abrupt Feature of ENSO Events, ADVANCES IN ATMOSPHERIC SCIENCES, 9, 131-146. doi: 10.1007/BF02657504
[5]	Boyin HUANG, ZHU Jiang, YANG Haijun, 2014: Mechanisms of Atlantic Meridional Overturning Circulation (AMOC) Variability in a Coupled Ocean-Atmosphere GCM, ADVANCES IN ATMOSPHERIC SCIENCES, 31, 241-251. doi: 10.1007/s00376-013-3021-3
[6]	ZHI Hai, ZHANG Rong-Hua, LIN Pengfei, WANG Lanning, 2015: Simulation of Salinity Variability and the Related Freshwater Flux Forcing in the Tropical Pacific: An Evaluation Using the Beijing Normal University Earth System Model (BNU-ESM), ADVANCES IN ATMOSPHERIC SCIENCES, 32, 1551-1564. doi: 10.1007/s00376-015-4240-6
[7]	YU Yongqiang, ZHANG Xuehong, GUO Yufu, 2004: Global Coupled Ocean-Atmosphere General Circulation Models in LASG/IAP, ADVANCES IN ATMOSPHERIC SCIENCES, 21, 444-455. doi: 10.1007/BF02915571
[8]	KANG Xianbiao, HUANG Ronghui, WANG Zhanggui, ZHANG Rong-Hua, 2014: Sensitivity of ENSO Variability to Pacific Freshwater Flux Adjustment in the Community Earth System Model, ADVANCES IN ATMOSPHERIC SCIENCES, 31, 1009-1021. doi: 10.1007/s00376-014-3232-2
[9]	ZHOU Tianjun, YU Yongqiang, LIU Hailong, LI Wei, YOU Xiaobao, ZHOU Guangqing, 2007: Progress in the Development and Application of Climate Ocean Models and Ocean-Atmosphere Coupled Models in China, ADVANCES IN ATMOSPHERIC SCIENCES, 24, 1109-1120. doi: 10.1007/s00376-007-1109-3
[10]	Zhou Guangqing, Zeng Qingcun, 2001: Predictions of ENSO with a Coupled Atmosphere-Ocean General Circulation Model, ADVANCES IN ATMOSPHERIC SCIENCES, 18, 587-603. doi: 10.1007/s00376-001-0047-8
[11]	YAN Li, WANG Panxing, YU Yongqiang, LI Lijuan, WANG Bin, 2010: Potential Predictability of Sea Surface Temperature in a Coupled Ocean--Atmosphere GCM, ADVANCES IN ATMOSPHERIC SCIENCES, 27, 921-936. doi: 10.1007/s00376-009-9062-y
[12]	FENG Lin, WU Dexing, LIN Xiaopei, MENG Xiangfeng, 2010: The Effect of Regional Ocean-Atmosphere Coupling on the Long-term Variability in the Pacific Ocean, ADVANCES IN ATMOSPHERIC SCIENCES, 27, 393-402. doi: 10.1007/s00376-009-8195-3
[13]	Yu Yongqiang, Yu Rucong, Zhang Xuehong, Liu Hailong, 2002: A Flexible Coupled Ocean-Atmosphere General Circulation Model, ADVANCES IN ATMOSPHERIC SCIENCES, 19, 169-190. doi: 10.1007/s00376-002-0042-8
[14]	Liu Shikuo, He Anguo, 1991: A Simple Quasi-Geostrophic Coupled Ocean-Atmosphere Model, ADVANCES IN ATMOSPHERIC SCIENCES, 8, 257-271. doi: 10.1007/BF02919608
[15]	Zhou Tianjun, Yu Rucong, Li Zhaoxin, 2002: ENSO-Dependent and ENSO-Independent Variability over the Mid-Latitude North Pacific: Observation and Air-Sea Coupled Model Simulation, ADVANCES IN ATMOSPHERIC SCIENCES, 19, 1127-1147. doi: 10.1007/s00376-002-0070-4
[16]	Ge SONG, Rongcai REN, 2023: The Subsurface and Surface Indian Ocean Dipoles and Their Association with ENSO in CMIP6 models, ADVANCES IN ATMOSPHERIC SCIENCES, 40, 975-987. doi: 10.1007/s00376-022-2086-2
[17]	ZHANG Qiong, GUAN Yue, YANG Haijun, 2008: ENSO Amplitude Change in Observation and Coupled Models, ADVANCES IN ATMOSPHERIC SCIENCES, 25, 361-366. doi: 10.1007/s00376-008-0361-5
[18]	Odd Helge OTTER, Helge DRANGE, 2004: A Possible Feedback Mechanism Involving the Arctic Freshwater,the Arctic Sea Ice, and the North Atlantic Drift, ADVANCES IN ATMOSPHERIC SCIENCES, 21, 784-801. doi: 10.1007/BF02916375
[19]	FENG Junqiao, HU Dunxin, YU Lejiang, 2012: Low-Frequency Coupled Atmosphere--Ocean Variability in the Southern Indian Ocean, ADVANCES IN ATMOSPHERIC SCIENCES, 29, 544-560. doi: 10.1007/s00376-011-1096-2
[20]	ZHENG Fei, ZHU Jiang, Rong-Hua ZHANG, ZHOU Guangqing, 2006: Improved ENSO Forecasts by Assimilating Sea Surface Temperature Observations into an Intermediate Coupled Model, ADVANCES IN ATMOSPHERIC SCIENCES, 23, 615-624. doi: 10.1007/s00376-006-0615-z

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Manuscript History

Manuscript received: 10 July 2012

Manuscript revised: 10 July 2012

通讯作者: 陈斌, bchen63@163.com

1.
沈阳化工大学材料科学与工程学院沈阳 110142

Modulation of El Nino-Southern Oscillation by Freshwater Flux and Salinity Variability in the Tropical Pacific

1. Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA;Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA, International Center for Climate and Environment Science, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029;Earth System Science Interdisciplinary Center, University of Maryland, College Park, Maryland, USA, The College of Physical and Environmental Oceanography, Ocean University of China, Qingdao 266003, State Key Laboratory of Satellite Ocean Environment Dyna;Department of Atmosphere and Ocean Science, University of Maryland, College Park, Maryland, USA;ational Marine Environmental Forecasting Center, State Oceanic Administration, Beijing 100081

Manuscript received: 2012-07-10
Manuscript revised: 2012-07-10

Abstract: The El Nino-Southern Oscillation (ENSO) is modulated by many factors; most previous studies have emphasized the roles of wind stress and heat flux in the tropical Pacific. Freshwater flux (FWF) is another environmental forcing to the ocean; its effect and the related ocean salinity variability in the ENSO region have been of increased interest recently. Currently, accurate quantifications of the FWF roles in the climate remain challenging; the related observations and coupled ocean-atmosphere modeling involve large elements of uncertainty. In this study, we utilized satellite-based data to represent FWF-induced feedback in the tropical Pacific climate system; we then incorporated these data into a hybrid coupled ocean-atmosphere model (HCM) to quantify its effects on ENSO. A new mechanism was revealed by which interannual FWF forcing modulates ENSO in a significant way. As a direct forcing, FWF exerts a significant influence on the ocean through sea surface salinity (SSS) and buoyancy flux (QB) in the western-central tropical Pacific. The SSS perturbations directly induced by ENSO-related interannual FWF variability affect the stability and mixing in the upper ocean. At the same time, the ENSO-induced FWF has a compensating effect on heat flux, acting to reduce interannual QB variability during ENSO cycles. These FWF-induced processes in the ocean tend to modulate the vertical mixing and entrainment in the upper ocean, enhancing cooling during La Nina and enhancing warming during El Nino, respectively. The interannual FWF forcing-induced positive feedback acts to enhance ENSO amplitude and lengthen its time scales in the tropical Pacific coupled climate system.

Keywords: