Improved Representation of Tropical Pacific Ocean–Atmosphere Dynamics in an Intermediate Complexity Climate Model

2014 ◽  
Vol 27 (1) ◽  
pp. 168-185 ◽  
Author(s):  
Ryan L. Sriver ◽  
Axel Timmermann ◽  
Michael E. Mann ◽  
Klaus Keller ◽  
Hugues Goosse
Keyword(s):  
Pacific Ocean ◽  
Surface Temperature ◽  
Climate Model ◽  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Temperature Variability ◽  
Tropical Pacific Ocean ◽  
Intermediate Complexity ◽  
Ocean Atmosphere ◽  
Perturbed Physics

Abstract A new anomaly coupling technique is introduced into a coarse-resolution dynamic climate model [the Liège Ocean Carbon Heteronomous model (LOCH)–Vegetation Continuous Description model (VECODE)–Earth System Models of Intermediate Complexity Climate deBilt (ECBILT)–Coupled Large-Scale Ice–Ocean model (CLIO)–Antarctic and Greenland Ice Sheet Model (AGISM) ensemble (LOVECLIM)], improving the model’s representation of eastern equatorial Pacific surface temperature variability. The anomaly coupling amplifies the surface diabatic atmospheric forcing within a Gaussian-shaped patch applied in the tropical Pacific Ocean. It is implemented with an improved predictive cloud scheme based on empirical relationships between cloud cover and key state variables. Results are presented from a perturbed physics ensemble systematically varying the parameters controlling the anomaly coupling patch size, location, and amplitude. The model’s optimal parameter combination is chosen through calibration against the observed power spectrum of monthly-mean surface temperature anomalies in the Niño-3 region. The calibrated model exhibits substantial improvement in equatorial Pacific interannual surface temperature variability and robustly reproduces El Niño–Southern Oscillation (ENSO)-like variability. The authors diagnose some of the key atmospheric and oceanic feedbacks in the model important for simulating ENSO-like variability, such as the positive Bjerknes feedback and the negative heat flux feedback, and analyze the recharge–discharge of the equatorial Pacific ocean heat content. They find LOVECLIM robustly captures important ocean dynamics related to thermocline adjustment and equatorial Kelvin waves. The calibrated model demonstrates some improvement in simulating atmospheric feedbacks, but the coupling between ocean and atmosphere is relatively weak. Because of the tractability of LOVECLIM and its consequent utility in exploring long-term climate variability and large ensemble perturbed physics experiments, improved representation of tropical Pacific ocean–atmosphere dynamics in the model may more readily allow for the investigation of the role of tropical Pacific ocean–atmosphere dynamics in past climate changes.

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 Reconstruction of seasonal temperature variability in the tropical Pacific Ocean from the shell of the scallop, Comptopallium radula

2007 ◽  
Vol 71 (4) ◽  
pp. 918-928 ◽  
Author(s):  
Julien Thébault ◽  
Laurent Chauvaud ◽  
Jacques Clavier ◽  
Jennifer Guarini ◽  
Robert B. Dunbar ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Tropical Pacific ◽  
Temperature Variability ◽  
Seasonal Temperature ◽  
Tropical Pacific Ocean ◽  
The Tropical Pacific

scholarly journals Forcing of the Indian Ocean Dipole on the Interannual Variations of the Tropical Pacific Ocean: Roles of the Indonesian Throughflow

2011 ◽  
Vol 24 (14) ◽  
pp. 3593-3608 ◽  
Author(s):  
Dongliang Yuan ◽  
Jing Wang ◽  
Tengfei Xu ◽  
Peng Xu ◽  
Zhou Hui ◽  
...  
Keyword(s):  
Pacific Ocean ◽  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Tropical Pacific ◽  
Equatorial Pacific ◽  
Indonesian Throughflow ◽  
Tropical Pacific Ocean ◽  
Equatorial Pacific Ocean ◽  
The Indian Ocean ◽  
The Tropical Pacific

Abstract Controlled numerical experiments using ocean-only and ocean–atmosphere coupled general circulation models show that interannual sea level depression in the eastern Indian Ocean during the Indian Ocean dipole (IOD) events forces enhanced Indonesian Throughflow (ITF) to transport warm water from the upper-equatorial Pacific Ocean to the Indian Ocean. The enhanced transport produces elevation of the thermocline and cold subsurface temperature anomalies in the western equatorial Pacific Ocean, which propagate to the eastern equatorial Pacific to induce significant coupled evolution of the tropical Pacific oceanic and atmospheric circulation. Analyses suggest that the IOD-forced ITF transport anomalies are about the same amplitudes as those induced by the Pacific ENSO. Results of the coupled model experiments suggest that the anomalies induced by the IOD persist in the equatorial Pacific until the year following the IOD event, suggesting the importance of the oceanic channel in modulating the interannual climate variations of the tropical Pacific Ocean at the time lag beyond one year.

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 Sensitivity study of the tropical Pacific precipitation anomalies

2016 ◽  
Author(s):  
Shouwen Zhang ◽  
Hua Jiang ◽  
Hui Wang ◽  
Ling Du ◽  
Dakui Wang
Keyword(s):  
Pacific Ocean ◽  
Sea Ice ◽  
North Atlantic ◽  
Climate Model ◽  
Tropical Pacific ◽  
Tropical Pacific Ocean ◽  
The North ◽  
Precipitation Anomalies ◽  
The North Atlantic ◽  
The Tropical Pacific

Abstract. Climate model results have shown that precipitation in the tropical Pacific Ocean will change up to 15 % and 25 % in one century. In this paper, both reanalysis data and climate model are used to study the response of global ocean and atmosphere to precipitation anomalies in the tropical Pacific Ocean. It shows that positive precipitation anomalies could trigger an El Nino-like SSTA response, with warmer SST in the east tropical Pacific Ocean and slightly cooler SST in the west tropical Pacific Ocean. The zonal tropical ocean currents change significantly, of which the magnitudes and directions are mainly relying on the intensity of the precipitation anomalies. Through a wave train encompassing the whole Northern Hemisphere named as the Circumglobal Waveguide Pattern (CWP), the North Atlantic atmospheric circulation responds to the freshwater anomalies in a NAO-like pattern. The anomalous atmospheric circulation transport sea ice to the North Atlantic Ocean. The sea ice melts in summer and freshen the upper ocean, which makes the ocean more stable. It thus constrains vertical heat transport and makes the upper water cooler, forming a significant positive feedback mechanism.

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