Changes in spring and Mei-yu extreme precipitation in the Western North Pacific and East Asia in the warmer climate in two high-resolution AGCMs

2020 ◽  
Author(s):  
Chao-An Chen ◽  
Huang-Hsiung Hsu
Keyword(s):  
High Resolution ◽  
Spatial Pattern ◽  
East Asia ◽  
Extreme Events ◽  
North Pacific ◽  
Extreme Precipitation ◽  
General Circulation ◽  
Western North Pacific ◽  
Future Climate Change ◽  
Sst Warming

<p>In this study, we estimate the changes in extreme precipitation indices over the western North Pacific and East Asia region (WNP-EA) during the spring and Mei-yu seasons in the warmer climate. Our analyses are based on two high-resolution atmospheric general circulation model simulations. The high-resolution atmospheric Model (HiRAM) was used in a series of simulations, which were forced by 4 sets of sea surface temperature (SST) changes under Representative Concentration Pathways 8.5 (RCP8.5) scenario. The Database for Policy Decision-Making for Future Climate Change (d4PDF) consists of global warming simulation outputs from MRI-AGCM3.2 with large ensemble members and multiple SST warming scenarios.</p><p>In the spring season, the changes in the spatial pattern of SDII, RX1day, and PR99 demonstrate greater enhancement over the northern flank of the climatological rainy region in both HiRAM and d4PDF, implying a northward extension of spring rain band. Besides, the changes in probability distribution display a shifting tendency that heavier extreme events occur more frequently in the warmer climate. The above changes are larger than the internal variability and uncertainty associated with SST warming patterns, indicating the robustness of the projected enhancement in precipitation intensity in the WNP-EA region. The spatial pattern for changes in CDD and total rainfall occurrence are less consistent between two datasets. In the Mei-yu season, the tendency toward more frequent extreme events in the probability distributions are consistently found in HiRAM and d4PDF. However, the changes in the spatial pattern of all indices are less consistent between HiRAM and d4PDF, implying larger uncertainty in the projection of extreme precipitation in the Mei-yu period in the warmer climate.</p>

scholarly journals Reintensification of the Anomalous Western North Pacific Anticyclone during the El Niño Modoki Decaying Summer: Relative Importance of Tropical Atlantic and Pacific SST Anomalies

2020 ◽  
Vol 33 (8) ◽  
pp. 3271-3288
Author(s):  
Juan Feng ◽  
Wen Chen ◽  
Xiaocong Wang
Keyword(s):  
El Niño ◽  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
El Nino ◽  
Central Pacific ◽  
El Niño Modoki ◽  
Sst Cooling ◽  
Sst Warming ◽  
Sst Anomalies

AbstractThe El Niño Modoki–induced anomalous western North Pacific anticyclone (WNPAC) undergoes an interesting reintensification process in the El Niño Modoki decaying summer, the period when El Niño Modoki decays but warm sea surface temperature (SST) anomalies over the tropical North Atlantic (TNA) and cold SST anomalies over the central-eastern Pacific (CEP) dominate. In this study, the region (TNA or CEP) in which the SST anomalies exert a relatively important influence on reintensification of the WNPAC is investigated. Observational analysis demonstrates that when only anomalous CEP SST cooling occurs, the WNPAC experiences a weak reintensification. In contrast, when only anomalous TNA SST warming emerges, the WNPAC experiences a remarkable reintensification. Numerical simulation analysis demonstrates that even though the same magnitude of CEP SST cooling and TNA warming is respectively set to force the atmospheric general circulation model, the response of the WNPAC is still much stronger in the TNA warming experiment than in the CEP cooling experiment. Further analysis demonstrates that this difference is caused by the distinct location of the effective tropical forcing between the CEP SST cooling and TNA SST warming for producing a WNPAC. The CEP cooling-induced effective anomalous diabatic cooling is located in the central Pacific, by which the forced anticyclone becomes gradually weak from the central Pacific to the western North Pacific. Thus, a weak WNPAC is produced. In contrast, as the TNA SST warming–induced effective anomalous diabatic cooling is just located in the western North Pacific via a Kelvin wave–induced Ekman divergence process, the forced anticyclone is significant and powerful in the western North Pacific.

scholarly journals Boreal Summer Synoptic-Scale Waves over the Western North Pacific in Multimodel Simulations

2016 ◽  
Vol 29 (12) ◽  
pp. 4487-4508 ◽  
Author(s):  
Haikun Zhao ◽  
Xianan Jiang ◽  
Liguang Wu
Keyword(s):  
Spatial Pattern ◽  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
Climate Model ◽  
Climate Modeling ◽  
Active Role ◽  
General Circulation Models ◽  
Boreal Summer ◽  
Synoptic Scale

During boreal summer, vigorous synoptic-scale wave (SSW) activity, often evident as southeast–northwest-oriented wave trains, prevails over the western North Pacific (WNP). In spite of their active role for regional weather and climate, modeling studies on SSWs are rather limited. In this study, a comprehensive survey on climate model capability in representing the WNP SSWs is conducted by analyzing simulations from 27 recent general circulation models (GCMs). Results suggest that it is challenging for GCMs to realistically represent the observed SSWs. Only 2 models out of the 27 GCMs generally well simulate both the intensity and spatial pattern of the observed SSW mode. Plausible key processes for realistic simulations of SSW activity are further explored. It is illustrated that GCM skill in representing the spatial pattern of the SSW is highly correlated to its skill in simulating the summer mean patterns of the low-level convergence associated with the WNP monsoon trough and conversion from eddy available potential energy (EAPE) to eddy kinetic energy (EKE). Meanwhile, simulated SSW intensity is found to be significantly correlated to the amplitude of 850-hPa vorticity, divergence, and conversion from EAPE to EKE over the WNP. The observed modulations of SSW activity by the Madden–Julian oscillation are able to be captured in several model simulations.

Seasonal precipitation change in the Western North Pacific and East Asia under global warming in two high-resolution AGCMs

2019 ◽  
Vol 53 (9-10) ◽  
pp. 5583-5605 ◽  
Author(s):  
Chao-An Chen ◽  
Huang-Hsiung Hsu ◽  
Chi-Cherng Hong ◽  
Ping-Gin Chiu ◽  
Chia-Ying Tu ◽  
...  
Keyword(s):  
Global Warming ◽  
High Resolution ◽  
East Asia ◽  
North Pacific ◽  
Western North Pacific ◽  
Precipitation Change ◽  
Seasonal Precipitation

scholarly journals Role of Subtropical Precipitation Anomalies in Maintaining the Summertime Meridional Teleconnection over the Western North Pacific and East Asia

2009 ◽  
Vol 22 (8) ◽  
pp. 2058-2072 ◽  
Author(s):  
Riyu Lu ◽  
Zhongda Lin
Keyword(s):  
East Asia ◽  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
Rainfall Variability ◽  
Lower Troposphere ◽  
Precipitation Anomaly ◽  
Teleconnection Patterns ◽  
Precipitation Anomalies

Abstract The meridional teleconnection patterns over the western North Pacific and East Asia (WNP–EA) during summer have a predominant role in affecting East Asian climate on the interannual time scale. A well-known seesaw pattern of tropical–subtropical precipitation is associated with the meridional teleconnection, and the subtropical precipitation anomaly has been previously viewed as a result of anomalous circulations associated with the teleconnection. In this study, however, the authors suggest that subtropical precipitation anomalies, in turn, can significantly affect large-scale circulations and may be crucial for maintenance of the meridional teleconnection. Diagnosis by using observational and reanalysis data indicates that the meridional teleconnection patterns are clearer in summers when the subtropical rainfall anomalies are greater. The simulated results by a linear baroclinic model indicate that a subtropical heat source, which is equivalent to the diagnosed positive subtropical precipitation anomaly, induces zonally elongated zonal wind anomalies that resemble the diagnosed ones in both the upper and lower troposphere over the extratropical WNP–EA. The simulated results also indicate that the horizontal and vertical structures of circulation responses are insensitive to the locations and shapes of imposed subtropical heat anomalies, which implies the important role of basic flow in circulation responses. This study suggests that, for confidential dynamical seasonal forecasting in East Asia, general circulation models should be required to capture the features of interannual subtropical rainfall variability and basic-state flows in WNP–EA.

scholarly journals Remote influence of the interannual variability of the Australian summer monsoon on wintertime climate in East Asia and the western North Pacific

2021 ◽  
pp. 1-54
Author(s):  
Shion Sekizawa ◽  
Hisashi Nakamura ◽  
Yu Kosaka
Keyword(s):  
East Asia ◽  
Interannual Variability ◽  
Observational Data ◽  
Summer Monsoon ◽  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
Convective Activity ◽  
Australian Summer Monsoon ◽  
Australian Summer

AbstractAnomalous convective activity in the Tropics forced by sea surface temperature (SST) variability exerts significant remote influence that provides a basis for seasonal prediction in the extratropics. In austral summer convective activity exhibits pronounced interannual variability over northern Australia (NAUS), which is, however, unlikely forced by SST anomalies but essentially a manifestation of internal variability of the Australian summer monsoon (AUSM) system. Based on observational data, the present study reveals its significant remote impacts on the wintertime climate in East Asia and the western North Pacific. The anomalous AUSM excites the Western Pacific (WP) pattern, as confirmed through an atmospheric general circulation model experiment. Through this cross-equatorial teleconnection, the enhanced AUSM leads to the strengthening of the East Asian winter monsoon with a colder winter over the Korean Peninsula and western Japan and reduced precipitation over southern China. The Okhotsk sea-ice extent decreases under warm anomalies and weakened offshore winds. The weakened AUSM leads to the same anomalies but with the opposite polarities. Our observational data analysis and numerical experiments reveal that the WP-like anomalies are excited by the propagation of stationary Rossby waves generated by anomalous upper-level divergent wind from NAUS that extends into the Northern Hemisphere subtropical jet. The climatological Hadley circulation is essential in this process. The concomitant anomalous diabatic heating over East Asia and feedback forcing by transient eddies along the Pacific stormtrack act to further amplify the WP-like response.

scholarly journals Multimodel Ensemble Projections of Wave Climate in the Western North Pacific Using CMIP6 Marine Surface Winds

2021 ◽  
Vol 9 (8) ◽  
pp. 835
Author(s):  
Mochamad Riam Badriana ◽  
Han Soo Lee
Keyword(s):  
North Pacific ◽  
General Circulation ◽  
Western North Pacific ◽  
Wave Climate ◽  
Coastal Development ◽  
Climate Projections ◽  
Surface Winds ◽  
Time Step ◽  
Wave Characteristics ◽  
Marine Surface

For decades, the western North Pacific (WNP) has been commonly indicated as a region with high vulnerability to oceanic and atmospheric hazards. This phenomenon can be observed through general circulation model (GCM) output from the Coupled Model Intercomparison Project (CMIP). The CMIP consists of a collection of ensemble data as well as marine surface winds for the projection of the wave climate. Wave climate projections based on the CMIP dataset are necessary for ocean studies, marine forecasts, and coastal development over the WNP region. Numerous studies with earlier phases of CMIP are abundant, but studies using CMIP6 as the recent dataset for wave projection is still limited. Thus, in this study, wave climate projections with WAVEWATCH III are conducted to investigate how wave characteristics in the WNP will have changed in 2050 and 2100 compared to those in 2000 with atmospheric forcings from CMIP6 marine surface winds. The wave model runs with a 0.5° × 0.5° spatial resolution in spherical coordinates and a 10-min time step. A total of eight GCMs from the CMIP6 dataset are used for the marine surface winds modelled over 3 hours for 2050 and 2100. The simulated average wave characteristics for 2000 are validated with the ERA5 Reanalysis wave data showing good consistency. The wave characteristics in 2050 and 2100 show that significant decreases in wave height, a clockwise shift in wave direction, and the mean wave period becomes shorter relative to those in 2000.

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