scholarly journals Sensitivity of a regional ocean-atmosphere coupled model to convection parameterization over western North Pacific

2011 ◽  
Vol 116 (D18) ◽  
Author(s):  
Liwei Zou ◽  
Tianjun Zhou
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Coupled Model ◽  
Ocean Atmosphere ◽  
Convection Parameterization

scholarly journals Can a Regional Ocean–Atmosphere Coupled Model Improve the Simulation of the Interannual Variability of the Western North Pacific Summer Monsoon?

2013 ◽  
Vol 26 (7) ◽  
pp. 2353-2367 ◽  
Author(s):  
Liwei Zou ◽  
Tianjun Zhou
Keyword(s):  
Interannual Variability ◽  
North Pacific ◽  
Western North Pacific ◽  
Coupled Model ◽  
The Philippines ◽  
Ocean Model ◽  
Land System ◽  
Anomalous Anticyclone ◽  
Ocean Atmosphere ◽  
Sst Anomalies

Abstract A flexible regional ocean–atmosphere–land system coupled model [Flexible Regional Ocean Atmosphere Land System (FROALS)] was developed through the Ocean Atmosphere Sea Ice Soil, version 3 (OASIS3), coupler to improve the simulation of the interannual variability of the western North Pacific summer monsoon (WNPSM). The regionally coupled model consists of a regional atmospheric model, the Regional Climate Model, version 3 (RegCM3), and a global climate ocean model, the National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG)/Institute of Atmospheric Physics (IAP) Climate Ocean Model (LICOM). The impacts of local air–sea interaction on the simulation of the interannual variability of the WNPSM are investigated through regionally ocean–atmosphere coupled and uncoupled simulations, with a focus on El Niño’s decaying summer. Compared with the uncoupled simulation, the regionally coupled simulation exhibits improvements in both the climatology and the interannual variability of rainfall over the WNP. In El Niño’s decaying summer, the WNP is dominated by an anomalous anticyclone, less rainfall, and enhanced subsidence, which lead to increases in the downward shortwave radiation flux, thereby warming sea surface temperature (SST) anomalies. Thus, the ocean appears as a slave to atmospheric forcing. In the uncoupled simulation, however, the atmosphere is a slave to oceanic SST forcing, with the warm SST anomalies located east of the Philippines unrealistically producing excessive rainfall. In the regionally coupled run, the unrealistic positive rainfall anomalies and the associated atmospheric circulations east of the Philippines are significantly improved, highlighting the importance of air–sea coupling in the simulation of the interannual variability of the WNPSM. One limitation of the model is that the anomalous anticyclone over the WNP is weaker than the observations in both the regionally coupled and the uncoupled simulations. This results from the weaker simulated climatological summer rainfall intensity over the monsoon trough.

Changes in the Past and Projected Western North Pacific Tropical Cyclone Activity in a Warmed Climate

2020 ◽  
Author(s):  
Liang Wu
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Climate Models ◽  
Rapid Development ◽  
Current Trend ◽  
Coupled Model ◽  
Rcp 8.5 ◽  
Projected Changes

<p><span>Two high-resolution climate models (the HiRAM and MRI-AGCM3.2) are used to simulate present-day western North Pacific (WNP) tropical cyclone (TC) activity and investigate </span><span>the </span><span>projected changes for the late 21<sup>st</sup> century. Compared </span><span>to</span><span>observation</span><span>s</span><span>, the models </span><span>are</span><span> able to realistically simulate many basic features of </span><span>the WNP</span><span> TC activity </span><span>climatolog</span><span>y. Future projections </span><span>with the coupled model inter-comparison project phase 5 (CMIP5) under Representative Concentration Pathway (RCP) 8.5 scenario</span><span> show a tendency for decreases in the number of WNP TCs</span><span>,</span> <span>and of</span><span> increase</span><span>s</span> <span>in the</span> <span>more intense </span><span>TCs. It is unknown to what cause this inverse variation with number and intensity should be generally linked to similar large-scale environmental conditions. To examine the WNP TC genesis and intensity with environmental variables, we show that most of the current trend of decreasing genesis of TCs can be attributed to weakened dynamic environments and the current trend of increasing intensity of TCs might be linked to increased thermodynamic environments. Thus, the future climate warms under RCP 8.5 will likely lead to strong reductions in TC genesis frequency over the WNP, with project decreases of 36-63% by the end of the twenty-first century, but lead to greater TC intensities with rapid development of thermodynamic environments.</span></p>

scholarly journals Intensification of the Western North Pacific Anticyclone Response to the Short Decaying El Niño Event due to Greenhouse Warming

2016 ◽  
Vol 29 (10) ◽  
pp. 3607-3627 ◽  
Author(s):  
Wei Chen ◽  
June-Yi Lee ◽  
Kyung-Ja Ha ◽  
Kyung-Sook Yun ◽  
Riyu Lu
Keyword(s):  
Global Warming ◽  
El Niño ◽  
North Pacific ◽  
Western North Pacific ◽  
Climate Models ◽  
El Nino ◽  
Coupled Model ◽  
Precipitation Anomaly ◽  
Historical Period ◽  
Central Pacific

Abstract Two types of El Niño evolution have been identified in terms of the lengths of their decaying phases: the first type is a short decaying El Niño that terminates in the following summer after the mature phase, and the second type is a long decaying one that persists until the subsequent winter. The responses of the western North Pacific anticyclone (WNPAC) anomaly to the two types of evolution are remarkably different. Using experiments from phase 5 of the Coupled Model Intercomparison Project (CMIP5), this study investigates how well climate models reproduce the two types of El Niño evolution and their impacts on the WNPAC in the historical period (1950–2005) and how they will change in the future under anthropogenic global warming. To reduce uncertainty in future projection, the nine best models are selected based on their performance in simulating El Niño evolution. In the historical run, the nine best models’ multimodel ensemble (B9MME) well reproduces the enhanced (weakened) WNPAC that is associated with the short (long) decaying El Niño. The comparison between results of the historical run for 1950–2005 and the representative concentration pathway 4.5 run for 2050–99 reveals that individual models and the B9MME tend to project no significant changes in the two types of El Niño evolution for the latter half of the twenty-first century. However, the WNPAC response to the short decaying El Niño is considerably intensified, being associated with the enhanced negative precipitation anomaly response over the equatorial central Pacific. This enhancement is attributable to the robust increase in mean and interannual variability of precipitation over the equatorial central Pacific under global warming.

scholarly journals Simulations of the Present and Late-Twenty-First-Century Western North Pacific Tropical Cyclone Activity Using a Regional Model

2014 ◽  
Vol 27 (9) ◽  
pp. 3405-3424 ◽  
Author(s):  
Liang Wu ◽  
Chia Chou ◽  
Cheng-Ta Chen ◽  
Ronghui Huang ◽  
Thomas R. Knutson ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
Statistical Significance ◽  
Regional Scale ◽  
Coupled Model ◽  
First Century ◽  
Significance Level ◽  
Twenty First Century

Abstract A high-resolution regional atmospheric model is used to simulate present-day western North Pacific (WNP) tropical cyclone (TC) activity and to investigate the projected changes for the late twenty-first century. Compared to observations, the model can realistically simulate many basic features of the WNP TC activity climatology, such as the TC genesis location, track, and lifetime. A number of spatial and temporal features of observed TC interannual variability are captured, although observed variations in basinwide TC number are not. A relatively well-simulated feature is the contrast of years when the Asian summer monsoon trough extends eastward (retreats westward), more (fewer) TCs form within the southeastern quadrant of the WNP, and the corresponding TC activity is above (below) normal over most parts of the WNP east of 125°E. Future projections with the Coupled Model Intercomparison Project phase 3 (CMIP3) A1B scenario show a weak tendency for decreases in the number of WNP TCs, and for increases in the more intense TCs; these simulated changes are significant at the 80% level. The present-day simulation of intensity is limited to storms of intensity less than about 55 m s−1. There is also a weak (80% significance level) tendency for projected WNP TC activity to shift poleward under global warming. A regional-scale feature is a projected increase of the TC activity north of Taiwan, which would imply an increase in TCs making landfall in north China, the Korean Peninsula, and parts of Japan. However, given the weak statistical significance found for the simulated changes, an assessment of the robustness of such regional-scale projections will require further study.

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