scholarly journals An Embedding Method for Improving Interannual Variability Simulations in a Hybrid Coupled Model of the Tropical Pacific Ocean–Atmosphere System

2004 ◽  
Vol 17 (14) ◽  
pp. 2794-2812 ◽  
Author(s):  
Rong-Hua Zhang ◽  
Stephen E. Zebiak
Keyword(s):  
Pacific Ocean ◽  
Interannual Variability ◽  
Coupled Model ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Embedding Method ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Hybrid Coupled Model ◽  
The Tropical Pacific

scholarly journals Freshwater Flux (FWF)-Induced Oceanic Feedback in a Hybrid Coupled Model of the Tropical Pacific

2009 ◽  
Vol 22 (4) ◽  
pp. 853-879 ◽  
Author(s):  
Rong-Hua Zhang ◽  
Antonio J. Busalacchi
Keyword(s):  
Heat Flux ◽  
Interannual Variability ◽  
Coupled Model ◽  
Tropical Pacific ◽  
Freshwater Flux ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
Hybrid Coupled Model ◽  
Sst Anomalies ◽  
The Tropical Pacific

Abstract The impacts of freshwater flux (FWF) forcing on interannual variability in the tropical Pacific climate system are investigated using a hybrid coupled model (HCM), constructed from an oceanic general circulation model (OGCM) and a simplified atmospheric model, whose forcing fields to the ocean consist of three components. Interannual anomalies of wind stress and precipitation minus evaporation, (P − E), are calculated respectively by their statistical feedback models that are constructed from a singular value decomposition (SVD) analysis of their historical data. Heat flux is calculated using an advective atmospheric mixed layer (AML) model. The constructed HCM can well reproduce interannual variability associated with ENSO in the tropical Pacific. HCM experiments are performed with varying strengths of anomalous FWF forcing. It is demonstrated that FWF can have a significant modulating impact on interannual variability. The buoyancy flux (QB) field, an important parameter determining the mixing and entrainment in the equatorial Pacific, is analyzed to illustrate the compensating role played by its two contributing parts: one is related to heat flux (QT) and the other to freshwater flux (QS). A positive feedback is identified between FWF and SST as follows: SST anomalies, generated by El Niño, nonlocally induce large anomalous FWF variability over the western and central regions, which directly influences sea surface salinity (SSS) and QB, leading to changes in the mixed layer depth (MLD), the upper-ocean stability, and the mixing and the entrainment of subsurface waters. These oceanic processes act to enhance the SST anomalies, which in turn feedback to the atmosphere in a coupled ocean–atmosphere system. As a result, taking into account anomalous FWF forcing in the HCM leads to an enhanced interannual variability and ENSO cycles. It is further shown that FWF forcing is playing a different role from heat flux forcing, with the former acting to drive a change in SST while the latter represents a passive response to the SST change. This HCM-based modeling study presents clear evidence for the role of FWF forcing in modulating interannual variability in the tropical Pacific. The significance and implications of these results are further discussed for physical understanding and model improvements of interannual variability in the tropical Pacific ocean–atmosphere system.

A local positive feedback of the tropical Pacific ocean-atmosphere system on interdecadal timescales

2006 ◽  
Vol 51 (5) ◽  
pp. 601-606 ◽  
Author(s):  
Chunhui Li ◽  
Dongxiao Wang ◽  
Jianyin Liang ◽  
Dejun Gu ◽  
Yun Liu
Keyword(s):  
Pacific Ocean ◽  
Positive Feedback ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Atmosphere System ◽  
Ocean Atmosphere ◽  
The Tropical Pacific

scholarly journals Weakened Interannual Variability in the Tropical Pacific Ocean since 2000

2013 ◽  
Vol 26 (8) ◽  
pp. 2601-2613 ◽  
Author(s):  
Zeng-Zhen Hu ◽  
Arun Kumar ◽  
Hong-Li Ren ◽  
Hui Wang ◽  
Michelle L’Heureux ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Interannual Variability ◽  
Southern Oscillation ◽  
Walker Circulation ◽  
Tropical Pacific ◽  
Warm Water ◽  
Water Volume ◽  
Tropical Pacific Ocean ◽  
Trade Winds ◽  
The Tropical Pacific

Abstract An interdecadal shift in the variability and mean state of the tropical Pacific Ocean is investigated within the context of changes in El Niño–Southern Oscillation (ENSO). Compared with 1979–99, the interannual variability in the tropical Pacific was significantly weaker in 2000–11, and this shift can be seen by coherent changes in both the tropical atmosphere and ocean. For example, the equatorial thermocline tilt became steeper during 2000–11, which was consistent with positive (negative) sea surface temperature anomalies, increased (decreased) precipitation, and enhanced (suppressed) convection in the western (central and eastern) tropical Pacific, which reflected an intensification of the Walker circulation. The combination of a steeper thermocline slope with stronger surface trade winds is proposed to have hampered the eastward migration of the warm water along the equatorial Pacific. As a consequence, the variability of the warm water volume was reduced and thus ENSO amplitude also decreased. Sensitivity experiments with the Zebiak–Cane model confirm the link between thermocline slope, wind stress, and the amplitude of ENSO.

scholarly journals Tropical Pacific Ocean Dynamical Response to Short-Term Sulfate Aerosol Forcing

2019 ◽  
Vol 32 (23) ◽  
pp. 8205-8221
Author(s):  
Tarun Verma ◽  
R. Saravanan ◽  
P. Chang ◽  
S. Mahajan
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Sulfate Aerosol ◽  
Upper Ocean ◽  
Sulfate Aerosols ◽  
Tropical Pacific Ocean ◽  
Aerosol Forcing ◽  
Ocean Atmosphere ◽  
The Tropical Pacific

Abstract The large-scale and long-term climate impacts of anthropogenic sulfate aerosols consist of Northern Hemisphere cooling and a southward shift of the tropical rain belt. On interannual time scales, however, the response to aerosols is localized with a sizable imprint on local ocean–atmosphere interaction. A large concentration of anthropogenic sulfates over Asia may impact ENSO by modifying processes and interactions that generate this coupled ocean–atmosphere variability. Here, we use climate model experiments with different degrees of ocean–atmosphere coupling to study the tropical Pacific response to an abrupt increase in anthropogenic sulfates. These include an atmospheric general circulation model (GCM) coupled to either a full-ocean GCM or a slab-ocean model, or simply forced by climatology of sea surface temperature. Comparing the responses helps differentiate between the fast atmospheric and slow ocean-mediated responses, and highlights the role of ocean–atmosphere coupling in the latter. We demonstrate the link between the Walker circulation and the equatorial Pacific upper-ocean dynamics in response to increased sulfate aerosols. The local surface cooling due to sulfate aerosols emitted over the Asian continent drives atmospheric subsidence over the equatorial west Pacific. The associated anomalous circulation imparts westerly momentum to the underlying Pacific Ocean, leading to an El Niño–like upper-ocean response and a transient warming of the east equatorial Pacific Ocean. The oceanic adjustment eventually contributes to its decay, giving rise to a damped oscillation of the tropical Pacific Ocean in response to abrupt anthropogenic sulfate aerosol forcing.

scholarly journals Coupled Model Biases Breed Spurious Low‐Frequency Variability in the Tropical Pacific Ocean

2018 ◽  
Vol 45 (19) ◽  
Author(s):  
Dhrubajyoti Samanta ◽  
Kristopher B. Karnauskas ◽  
Nathalie F. Goodkin ◽  
Sloan Coats ◽  
Jason E. Smerdon ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Low Frequency ◽  
Coupled Model ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Model Biases ◽  
Low Frequency Variability ◽  
The Tropical Pacific

scholarly journals The Equatorial Thermocline Outcropping—A Seasonal Control on the Tropical Pacific Ocean–Atmosphere Instability Strength

2002 ◽  
Vol 15 (19) ◽  
pp. 2721-2739 ◽  
Author(s):  
Eli Galanti ◽  
Eli Tziperman ◽  
Matthew Harrison ◽  
Antony Rosati ◽  
Ralf Giering ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
Equatorial Thermocline ◽  
Ocean Atmosphere ◽  
The Tropical Pacific
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