scholarly journals Past and Projected Changes in Western North Pacific Tropical Cyclone Exposure

2016 ◽  
Vol 29 (16) ◽  
pp. 5725-5739 ◽  
Author(s):  
James P. Kossin ◽  
Kerry A. Emanuel ◽  
Suzana J. Camargo
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Southern China ◽  
Numerical Models ◽  
North Pacific Ocean ◽  
Eastern China ◽  
Coupled Model ◽  
The Philippines ◽  
Ryukyu Islands ◽  
The Past

Abstract The average latitude where tropical cyclones (TCs) reach their peak intensity has been observed to be shifting poleward in some regions over the past 30 years, apparently in concert with the independently observed expansion of the tropical belt. This poleward migration is particularly well observed and robust in the western North Pacific Ocean (WNP). Such a migration is expected to cause systematic changes, both increases and decreases, in regional hazard exposure and risk, particularly if it persists through the present century. Here, it is shown that the past poleward migration in the WNP has coincided with decreased TC exposure in the region of the Philippine and South China Seas, including the Marianas, the Philippines, Vietnam, and southern China, and increased exposure in the region of the East China Sea, including Japan and its Ryukyu Islands, the Korea Peninsula, and parts of eastern China. Additionally, it is shown that projections of WNP TCs simulated by, and downscaled from, an ensemble of numerical models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) demonstrate a continuing poleward migration into the present century following the emissions projections of the representative concentration pathway 8.5 (RCP8.5). The projected migration causes a shift in regional TC exposure that is very similar in pattern and relative amplitude to the past observed shift. In terms of regional differences in vulnerability and resilience based on past TC exposure, the potential ramifications of these future changes are significant. Questions of attribution for the changes are discussed in terms of tropical belt expansion and Pacific decadal sea surface temperature variability.

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.

scholarly journals Modulation of Western North Pacific Tropical Cyclone Activity by the ISO. Part II: Tracks and Landfalls

2013 ◽  
Vol 26 (9) ◽  
pp. 2919-2930 ◽  
Author(s):  
Richard C. Y. Li ◽  
Wen Zhou
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
North Pacific Ocean ◽  
Phase 1 ◽  
Intraseasonal Oscillation ◽  
The Philippines ◽  
Subtropical High ◽  
Southern Flank

Abstract This study investigates how tropical cyclone (TC) tracks and landfalls are modulated by the two major components of the intraseasonal oscillation (ISO), the 30–60-day Madden–Julian oscillation (MJO) and the 10–20-day quasi-biweekly oscillation (QBWO). In the convective phases of the MJO (phases 7 + 8 and 1 + 2), the western North Pacific Ocean (WNP) is mainly clustered with westward- and northwestward-moving TCs. The strong easterlies (southeasterlies) in the southern flank of the subtropical high lead to an increase in TC activity and landfalls in the Philippines and Vietnam (China and Japan) in phase 7 + 8 (phase 1 + 2). In the nonconvective phases (phases 3 + 4 and 5 + 6), TCs change from the original straight-moving type to the recurving type, such that the tendency for landfalls is significantly reduced. The QBWO, on the other hand, has a significant influence on TC landfalls in the Philippines and Japan. The strengthening of the subtropical high in phase 1 + 2 favors the development of westward-moving TCs and results in an increase in landfalls in the Philippines, while in phase 3 + 4 (phase 5 + 6), there is an increase (decrease) in TC activity and landfalls in Japan because of changes in genesis locations and large-scale circulations. The results herein suggest that both the MJO and QBWO exert distinctive impacts on TCs in the WNP.

scholarly journals Long-Term Changes in Rainfall over Eastern China and Large-Scale Atmospheric Circulation Associated with Recent Global Warming

2010 ◽  
Vol 23 (6) ◽  
pp. 1544-1562 ◽  
Author(s):  
Ping Zhao ◽  
Song Yang ◽  
Rucong Yu
Keyword(s):  
Tibetan Plateau ◽  
North Pacific ◽  
Rainy Season ◽  
Western North Pacific ◽  
Southern China ◽  
Eastern China ◽  
Northern China ◽  
Positive Trend ◽  
Eastern Tibetan Plateau

Abstract Using precipitation data from rain gauge stations over China, the authors examine the long-term variation of the durations of persistent rainfall over eastern China for the past 40 years. The variation in the regional rainfall was related to a change in the global-mean surface temperature from the relatively cold period of the 1960s–70s to the relatively warm period of the 1980s–90s. Compared to the cold period, the persistent rainfall in the warm period began earlier and ended later over southern China, lengthening the rainy season by 23 days, but it began later and ended earlier over northern China, shortening the rainy season by 14 days. This change in the durations of persistent rainfall contributed to the pattern of the long-term change in rainfall: southern floods and northern droughts. The earlier beginning of the rainy season over southern China was associated with a more westward subtropical high over the western North Pacific and a stronger low-level low near the eastern Tibetan Plateau during spring. On the other hand, the later ending of the rainy season over southern China and the shorter rainy season over northern China were related to a more westward subtropical high over the western Pacific and a weaker trough near the eastern Tibetan Plateau during summer. The snow cover over the Tibetan Plateau exhibited a positive trend in winter and spring, which increased the local soil moisture content and cooled the overlying atmosphere during spring and summer. The sea surface temperature over the tropical Indian Ocean and the western North Pacific also displayed a positive trend. The cooling over land and the warming over oceans reduced the thermal contrast between East Asia and the adjacent oceans. Moreover, the low-level low pressure system over East Asia weakened during summer. Under such circumstances, the East Asian summer monsoon circulation weakened, with anomalous northerly winds over eastern China. Correspondingly, the mei-yu front stagnated over the Yangtze River valley, and the associated pattern of vertical motions increased the rainfall over the valley and decreased the rainfall over northern China.

scholarly journals A Statistical Model of Tropical Cyclone Tracks in the Western North Pacific with ENSO-Dependent Cyclogenesis

2011 ◽  
Vol 50 (8) ◽  
pp. 1725-1739 ◽  
Author(s):  
Emmi Yonekura ◽  
Timothy M. Hall
Keyword(s):  
Tropical Cyclone ◽  
Statistical Model ◽  
North Pacific ◽  
Western North Pacific ◽  
Southern Oscillation ◽  
North Pacific Ocean ◽  
The Philippines ◽  
Tropical Cyclone Genesis ◽  
Cyclone Genesis ◽  
Index Value

AbstractA new statistical model for western North Pacific Ocean tropical cyclone genesis and tracks is developed and applied to estimate regionally resolved tropical cyclone landfall rates along the coasts of the Asian mainland, Japan, and the Philippines. The model is constructed on International Best Track Archive for Climate Stewardship (IBTrACS) 1945–2007 historical data for the western North Pacific. The model is evaluated in several ways, including comparing the stochastic spread in simulated landfall rates with historic landfall rates. Although certain biases have been detected, overall the model performs well on the diagnostic tests, for example, reproducing well the geographic distribution of landfall rates. Western North Pacific cyclogenesis is influenced by El Niño–Southern Oscillation (ENSO). This dependence is incorporated in the model’s genesis component to project the ENSO-genesis dependence onto landfall rates. There is a pronounced shift southeastward in cyclogenesis and a small but significant reduction in basinwide annual counts with increasing ENSO index value. On almost all regions of coast, landfall rates are significantly higher in a negative ENSO state (La Niña).

scholarly journals Dominant Mode of Climate Variability, Intermodel Diversity, and Projected Future Changes over the Summertime Western North Pacific Simulated in the CMIP3 Models

2011 ◽  
Vol 24 (15) ◽  
pp. 3935-3955 ◽  
Author(s):  
Yu Kosaka ◽  
Hisashi Nakamura
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Low Frequency ◽  
Coupled Model ◽  
Lower Troposphere ◽  
The Philippines ◽  
Dominant Mode ◽  
Intergovernmental Panel ◽  
Projected Change ◽  
Mean State

Abstract A set of multimodel twentieth-century climate simulations for phase 3 of the Coupled Model Intercomparison Project (CMIP3) is analyzed to assess the model reproducibility of the Pacific–Japan (PJ) teleconnection pattern. It is the dominant low-frequency anomaly pattern over the summertime western North Pacific (WNP), characterized by a meridional dipole of zonally elongated vorticity anomalies in the lower troposphere and by anomalous precipitation over the tropical WNP. Most of the models can reproduce the PJ pattern reasonably well as one of the leading anomaly patterns or their combination. The model reproducibility of the pattern tends to be higher for those models in which the climatological-mean state over the WNP is better reproduced. Furthermore, intermodel diversity in the summertime climatological-mean fields over the WNP, especially in the lower troposphere, is found to be large and projected most strongly onto the observed PJ pattern. Nevertheless, the multimodel ensemble (MME) mean of these climatological-mean states is close to the observations. Projected future changes in the summertime climatological-mean state under the Intergovernmental Panel on Climate Change’s (IPCC) Special Report on Emission Scenarios (SRES) A1B also bear certain similarities with the PJ pattern, in a manner consistent with the aforementioned sensitivity of the model climate to that pattern. The MME projection indicates an overall increase in precipitation over the entire tropics, but it is overwhelmed locally by the effects of the enhanced tropospheric stratification over the tropical WNP. A resultant local reduction of the mean ascent is dynamically consistent with the anticyclonic projection around the Philippines and the cyclonic projection around Japan in MME, as in the observed anomalous dipole associated with the PJ pattern. However, the polarity and magnitude of the PJ-like projected change vary substantially from one model to another.

scholarly journals Mesoscale Features Associated with Tropical Cyclone Formations in the Western North Pacific

2008 ◽  
Vol 136 (6) ◽  
pp. 2006-2022 ◽  
Author(s):  
Cheng-Shang Lee ◽  
Kevin K. W. Cheung ◽  
Jenny S. N. Hui ◽  
Russell L. Elsberry
Keyword(s):  
Tropical Cyclone ◽  
North Pacific ◽  
Western North Pacific ◽  
Large Scale ◽  
North Pacific Ocean ◽  
Deep Convection ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Synoptic Patterns ◽  
The Mean

Abstract The mesoscale features of 124 tropical cyclone formations in the western North Pacific Ocean during 1999–2004 are investigated through large-scale analyses, satellite infrared brightness temperature (TB), and Quick Scatterometer (QuikSCAT) oceanic wind data. Based on low-level wind flow and surge direction, the formation cases are classified into six synoptic patterns: easterly wave (EW), northeasterly flow (NE), coexistence of northeasterly and southwesterly flow (NE–SW), southwesterly flow (SW), monsoon confluence (MC), and monsoon shear (MS). Then the general convection characteristics and mesoscale convective system (MCS) activities associated with these formation cases are studied under this classification scheme. Convection processes in the EW cases are distinguished from the monsoon-related formations in that the convection is less deep and closer to the formation center. Five characteristic temporal evolutions of the deep convection are identified: (i) single convection event, (ii) two convection events, (iii) three convection events, (iv) gradual decrease in TB, and (v) fluctuating TB, or a slight increase in TB before formation. Although no dominant temporal evolution differentiates cases in the six synoptic patterns, evolutions ii and iii seem to be the common routes taken by the monsoon-related formations. The overall percentage of cases with MCS activity at multiple times is 63%, and in 35% of cases more than one MCS coexisted. Most of the MC and MS cases develop multiple MCSs that lead to several episodes of deep convection. These two patterns have the highest percentage of coexisting MCSs such that potential interaction between these systems may play a role in the formation process. The MCSs in the monsoon-related formations are distributed around the center, except in the NE–SW cases in which clustering of MCSs is found about 100–200 km east of the center during the 12 h before formation. On average only one MCS occurs during an EW formation, whereas the mean value is around two for the other monsoon-related patterns. Both the mean lifetime and time of first appearance of MCS in EW are much shorter than those developed in other synoptic patterns, which indicates that the overall formation evolution in the EW case is faster. Moreover, this MCS is most likely to be found within 100 km east of the center 12 h before formation. The implications of these results to internal mechanisms of tropical cyclone formation are discussed in light of other recent mesoscale studies.

scholarly journals Differing Growth Responses of Major Phylogenetic Groups of Marine Bacteria to Natural Phytoplankton Blooms in the Western North Pacific Ocean

2011 ◽  
Vol 77 (12) ◽  
pp. 4055-4065 ◽  
Author(s):  
Yuya Tada ◽  
Akito Taniguchi ◽  
Ippei Nagao ◽  
Takeshi Miki ◽  
Mitsuo Uematsu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Bacterial Community ◽  
North Pacific ◽  
Bacterial Production ◽  
Western North Pacific ◽  
Bacterial Abundance ◽  
North Pacific Ocean ◽  
Growth Potential ◽  
Phytoplankton Blooms ◽  
Content Type

ABSTRACTGrowth and productivity of phytoplankton substantially change organic matter characteristics, which affect bacterial abundance, productivity, and community structure in aquatic ecosystems. We analyzed bacterial community structures and measured activities inside and outside phytoplankton blooms in the western North Pacific Ocean by using bromodeoxyuridine immunocytochemistry and fluorescencein situhybridization (BIC-FISH).Roseobacter/Rhodobacter, SAR11,Betaproteobacteria,Alteromonas, SAR86, andBacteroidetesresponded differently to changes in organic matter supply.Roseobacter/Rhodobacterbacteria remained widespread, active, and proliferating despite large fluctuations in organic matter and chlorophylla(Chl-a) concentrations. The relative contribution ofBacteroidetesto total bacterial production was consistently high. Furthermore, we documented the unexpectedly large contribution ofAlteromonasto total bacterial production in the bloom. Bacterial abundance, productivity, and growth potential (the proportion of growing cells in a population) were significantly correlated with Chl-aand particulate organic carbon concentrations. Canonical correspondence analysis showed that organic matter supply was critical for determining bacterial community structures. The growth potential of each bacterial group as a function of Chl-aconcentration showed a bell-shaped distribution, indicating an optimal organic matter concentration to promote growth. The growth ofAlteromonasandBetaproteobacteriawas especially strongly correlated with organic matter supply. These data elucidate the distinctive ecological role of major bacterial taxa in organic matter cycling during open ocean phytoplankton blooms.

Satellite-Derived Tropical Cyclone Intensity in the North Pacific Ocean Using the Deviation-Angle Variance Technique

2014 ◽  
Vol 29 (3) ◽  
pp. 505-516 ◽  
Author(s):  
Elizabeth A. Ritchie ◽  
Kimberly M. Wood ◽  
Oscar G. Rodríguez-Herrera ◽  
Miguel F. Piñeros ◽  
J. Scott Tyo
Keyword(s):  
Tropical Cyclone ◽  
North Atlantic ◽  
North Pacific ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Deviation Angle ◽  
Intensity Estimation ◽  
The North ◽  
The North Atlantic ◽  
The North Pacific

Abstract The deviation-angle variance technique (DAV-T), which was introduced in the North Atlantic basin for tropical cyclone (TC) intensity estimation, is adapted for use in the North Pacific Ocean using the “best-track center” application of the DAV. The adaptations include changes in preprocessing for different data sources [Geostationary Operational Environmental Satellite-East (GOES-E) in the Atlantic, stitched GOES-E–Geostationary Operational Environmental Satellite-West (GOES-W) in the eastern North Pacific, and the Multifunctional Transport Satellite (MTSAT) in the western North Pacific], and retraining the algorithm parameters for different basins. Over the 2007–11 period, DAV-T intensity estimation in the western North Pacific results in a root-mean-square intensity error (RMSE, as measured by the maximum sustained surface winds) of 14.3 kt (1 kt ≈ 0.51 m s−1) when compared to the Joint Typhoon Warning Center best track, utilizing all TCs to train and test the algorithm. The RMSE obtained when testing on an individual year and training with the remaining set lies between 12.9 and 15.1 kt. In the eastern North Pacific the DAV-T produces an RMSE of 13.4 kt utilizing all TCs in 2005–11 when compared with the National Hurricane Center best track. The RMSE for individual years lies between 9.4 and 16.9 kt. The complex environment in the western North Pacific led to an extension to the DAV-T that includes two different radii of computation, producing a parametric surface that relates TC axisymmetry to intensity. The overall RMSE is reduced by an average of 1.3 kt in the western North Pacific and 0.8 kt in the eastern North Pacific. These results for the North Pacific are comparable with previously reported results using the DAV for the North Atlantic basin.

scholarly journals Observations of Upper-Tropospheric Influence on a Monsoon Trough over the Western North Pacific

2014 ◽  
Vol 142 (4) ◽  
pp. 1472-1488 ◽  
Author(s):  
Biao Geng ◽  
Kunio Yoneyama ◽  
Ryuichi Shirooka
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
North Pacific Ocean ◽  
Low Pressure ◽  
Monsoon Trough ◽  
Pressure Cell ◽  
Intensive Observations ◽  
Upper Level ◽  
Synoptic Observations ◽  
Eastern Edge

Abstract This study examined the synoptic evolution and internal structure of a monsoon trough in association with the deep equatorward intrusion of a midlatitude upper trough in the western North Pacific Ocean in June 2008. The study was based on data from routine synoptic observations and intensive observations conducted on board the research vessel Mirai at 12°N, 135°E. The monsoon trough was first observed to extend southeastward from the center of a tropical depression. It then moved northward, with its eastern edge moving faster and approaching a surface low pressure cell induced by the upper trough. The distinct northward migration caused the monsoon trough to become oriented from the southwest to the northeast. The monsoon trough merged with the surface low pressure cell and extended broadly northeastward. The passage of the monsoon trough over the Mirai was accompanied by lower pressure, higher air and sea surface temperature, and minimal rainfall. The monsoon trough extended upward to nearly 500 hPa and sloped southward with height. It was overlain by northwesterly winds, negative geopotential height and temperature anomalies, and extremely dry air in the upper troposphere. Precipitation systems were weak and scattered near the monsoon trough but were intense and extensive south of the surface monsoon trough, where intense low-level convergence and upper-level divergence caused deep and vigorous upward motion. It appears that the upper trough exerted important impacts on the development of both the monsoon trough and associated precipitation, which are discussed according to the observational results.

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