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.

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 Seasonal Modulation of Tropical Intraseasonal Oscillations on Tropical Cyclone Geneses in the Western North Pacific

2011 ◽  
Vol 24 (24) ◽  
pp. 6339-6352 ◽  
Author(s):  
Ping Huang ◽  
Chia Chou ◽  
Ronghui Huang
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Asian Summer Monsoon ◽  
North Pacific Ocean ◽  
Intraseasonal Oscillation ◽  
Monsoon Trough ◽  
Intraseasonal Oscillations ◽  
Asian Summer ◽  
Primary Contribution

Abstract The seasonal modulation of tropical intraseasonal oscillation (TISO) on tropical cyclone (TC) geneses over the western North Pacific Ocean (WNP) is investigated in three periods of the WNP TC season: May–June (MJ), July–September (JAS), and October–December (OND). The modulation of the TISO–TC geneses over the WNP is strong in MJ, while it appears weaker in JAS and OND. In MJ, TISO propagates northward via two routes, the west route through the South China Sea and the east route through the WNP monsoon trough region, which are two clustering locations of TC geneses. TISO can synchronously influence most TC geneses over these two regions. In JAS, however, the modulation is out of phase between the monsoon trough region and the East Asian summer monsoon region, as well as the WNP subtropical high region, as a result of further northward propagation of TISO and scattered TC geneses. The TISO–TC genesis modulation in each individual region is comparable to that in MJ, although the modulation over the entire WNP in JAS appears weaker. In OND, TISO has a stronger influence on TC geneses west than east of 150°E because TISO decays and its convection center located at the equator is out of the TC genesis region when propagating eastward into east of 150°E. Midlevel relative humidity is the primary contribution to the modulations of TISO on the genesis environment, while vorticity could contribute to the modulation over the subtropics in JAS.

scholarly journals Projected Changes in Late-Twenty-First-Century Tropical Cyclone Frequency in 13 Coupled Climate Models from Phase 5 of the Coupled Model Intercomparison Project

2013 ◽  
Vol 26 (24) ◽  
pp. 9946-9959 ◽  
Author(s):  
K. J. Tory ◽  
S. S. Chand ◽  
J. L. McBride ◽  
H. Ye ◽  
R. A. Dare
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Climate Models ◽  
Coupled Model ◽  
Reanalysis Data ◽  
First Century ◽  
Model Intercomparison ◽  
Intercomparison Project ◽  
Twenty First Century ◽  
Projected Changes

Abstract Changes in tropical cyclone (TC) frequency under anthropogenic climate change are examined for 13 global models from phase 5 of the Coupled Model Intercomparison Project (CMIP5), using the Okubo–Weiss–Zeta parameter (OWZP) TC-detection method developed by the authors in earlier papers. The method detects large-scale conditions within which TCs form. It was developed and tuned in atmospheric reanalysis data and then applied without change to the climate models to ensure model and detector independence. Changes in TC frequency are determined by comparing TC detections in the CMIP5 historical runs (1970–2000) with high emission scenario (representative concentration pathway 8.5) future runs (2070–2100). A number of the models project increases in frequency of higher-latitude tropical cyclones in the late twenty-first century. Inspection reveals that these high-latitude systems were subtropical in origin and are thus eliminated from the analysis using an objective classification technique. TC detections in 8 of the 13 models reproduce observed TC formation numbers and geographic distributions reasonably well, with annual numbers within ±50% of observations. TC detections in the remaining five models are particularly low in number (10%–28% of observed). The eight models with a reasonable TC climatology all project decreases in global TC frequency varying between 7% and 28%. Large intermodel and interbasin variations in magnitude and sign are present, with the greatest variations in the Northern Hemisphere basins. These results are consistent with results from earlier-generation climate models and thus confirm the robustness of coupled model projections of globally reduced TC frequency.

scholarly journals Projected Changes in Temperature and Precipitation Extremes in China by the CMIP5 Multimodel Ensembles

2014 ◽  
Vol 27 (17) ◽  
pp. 6591-6611 ◽  
Author(s):  
Botao Zhou ◽  
Qiuzi Han Wen ◽  
Ying Xu ◽  
Lianchun Song ◽  
Xuebin Zhang
Keyword(s):  
Regional Scale ◽  
Coupled Model ◽  
First Century ◽  
Precipitation Extremes ◽  
Dominant Factor ◽  
Emission Scenarios ◽  
Temperature And Precipitation ◽  
Twenty First Century ◽  
The Difference ◽  
Projected Changes

Abstract This paper presents projected changes in temperature and precipitation extremes in China by the end of the twenty-first century based on the Coupled Model Intercomparison Project phase 5 (CMIP5) simulations. The temporal changes and their spatial patterns in the Expert Team on Climate Change Detection and Indices (ETCCDI) indices under the RCP4.5 and RCP8.5 emission scenarios are analyzed. Compared to the reference period 1986–2005, substantial changes are projected in temperature and precipitation extremes under both emission scenarios. These changes include a decrease in cold extremes, an increase in warm extremes, and an intensification of precipitation extremes. The intermodel spread in the projection increases with time, with wider spread under RCP8.5 than RCP4.5 for most indices, especially at the subregional scale. The difference in the projected changes under the two RCPs begins to emerge in the 2040s. Analyses based on the mixed-effects analysis of variance (ANOVA) model indicate that by the end of the twenty-first century, at the national scale, the dominant contributor to the projection uncertainty of most temperature-based indices, and some precipitation extremes [including maximum 1-day precipitation (RX1day) and maximum 5-day precipitation (RX5day), and total extremely wet day total amount (R95p)], is the difference in emission scenarios. By the end of the twenty-first century, model uncertainty is the dominant factor at the regional scale and for the other indices. Natural variability can also play very important role.

scholarly journals Evaluation of Simulation Capability for Multiple Tropical Cyclone Events in the Western North Pacific of the UH_HCM Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Tianhang Li ◽  
Hong-Li Ren ◽  
Yujie Wu ◽  
Jianyun Gao
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
Intraseasonal Variability ◽  
Coupled Model ◽  
Active Phase ◽  
Monsoon Trough ◽  
Factors Affecting ◽  
Potential Index

The intraseasonal variability of multiple tropical cyclone (MTC) events in the western North Pacific (WNP) during 1979–2015 is analyzed using the best-track dataset archived at the Joint Typhoon Warning Center. MTC events are divided into three phases according to the time intervals of the tropical cyclone (TC) genesis, that is, active, normal, and inactive phases. Composite analysis results indicate that MTC events tend to occur in the active phase when the monsoon trough is stronger and located farther north than at other times. Initialized by the data from a 10-year stable running result, a 12-year control experiment is carried out using the hybrid atmosphere–ocean coupled model developed at the University of Hawaii (UH_HCM model) to evaluate its simulation capability. Compared with the climate observations, the model shows good skill in simulating the large-scale environmental conditions in the WNP, especially the subtropical high and the monsoon trough. In addition, the model can well simulate the climate characteristics of TCs in the WNP, as well as the differences in each MTC phase. However, the simulated frequency of TCs is less and their locations are more northeast, compared with the observations. The vorticity and moisture in the model appear to be the two main factors affecting MTC activity based on analyses of the genesis potential index.

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