scholarly journals Seasonal prediction skill of East Asian summer monsoon in CMIP5 models

2018 ◽  
Vol 9 (3) ◽  
pp. 985-997
Author(s):  
Bo Huang ◽  
Ulrich Cubasch ◽  
Christopher Kadow
Keyword(s):  
Summer Monsoon ◽  
Zonal Wind ◽  
East Asian Summer Monsoon ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Prediction Skill ◽  
Coupled Mode ◽  
Asian Summer ◽  
Prediction Systems

Abstract. The East Asian summer monsoon (EASM) is an important part of the global climate system and plays a vital role in the Asian climate. Its seasonal predictability is a long-standing issue within the monsoon scientist community. In this study, we analyse the seasonal (the leading time is at least 6 months) prediction skill of the EASM rainfall and its associated general circulation in non-initialised and initialised simulations for the years 1979–2005, which are performed by six prediction systems (i.e. the BCC-CSM1-1, the CanCM4, the GFDL-CM2p1, the HadCM3, the MIROC5, and the MPI-ESM-LR) from the Coupled Model Intercomparison Project phase 5 (CMIP 5). We find that most prediction systems of simulated zonal wind over 850 and 200 hPa are significantly improved in the initialised simulations compared to non-initialised simulations. Based on the knowledge that zonal wind indices can be used as potential predictors for the EASM, we select an EASM index based upon the zonal wind over 850 hPa for further analysis. This assessment shows that the GFDL-CM2p1 and the MIROC5 added prediction skill in simulating the EASM index with initialisation, the BCC-CSM1-1, the CanCM4, and the MPI-ESM-LR changed the skill insignificantly, and the HadCM3 indicates a decreased skill score. The different responses to initialisation can be traced back to the ability of the models to capture the ENSO (El Niño–Southern Oscillation) and EASM coupled mode, particularly the Southern Oscillation–EASM coupled mode. As is known from observation studies, this mode links the oceanic circulation and the EASM rainfall. Overall, the GFDL-CM2p1 and the MIROC5 are capable of predicting the EASM on a seasonal timescale under the current initialisation strategy.

scholarly journals Seasonal prediction skill of East Asian summer monsoon in CMIP5-Models

2017 ◽  
Author(s):  
Bo Huang ◽  
Ulrich Cubasch ◽  
Christopher Kadow
Keyword(s):  
Summer Monsoon ◽  
Zonal Wind ◽  
East Asian Summer Monsoon ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Prediction Skill ◽  
Cmip5 Models ◽  
Coupled Mode ◽  
Asian Summer

Abstract. The East Asian summer monsoon (EASM) is an important part of the global climate system and plays a vital role in the Asian climate. Its sub-seasonal-to-seasonal predictability is a long-standing issue within the monsoon scientist community. In this study, we analyse the seasonal (with six months lead time) prediction skill of the EASM rainfall and its associated general circulation in non-initialised and initialised simulations for the years 1979–2005 performed by six prediction systems (i.e., the BCC-CSM1-1, the CanCM4, the GFDL-CM2p1, the HadCM3, the MIROC5 and the MPI-ESM-LR) from the Coupled Model Intercomparison Project phase 5 (CMIP 5). We find that the simulation of the zonal wind is significantly improved in initialised simulations compared to non-initialized simulations. Based on the knowledge that zonal wind indices can be used as potential predictors for the EASM, we selected an EASM index based upon the zonal wind for further analysis. The assessment show that the GFDL-CM2p1 and the MIROC5 add prediction skill in simulating the EASM index with initialisation, the BCC-CSM1-1, the CanCM4, and the MPI-ESM-LR change the skill insignificantly, and the HadCM3 indicates a decreased skill score. The different response to the initialisation can be traced back to the ability of the models to capture the ENSO (El Niño-Southern Oscillation)-EASM coupled mode, particularly the Southern Oscillation-EASM coupled mode. In summary, we find that the GFDL-CM2p1 and the MIROC5 are capable to predict the EASM on a seasonal time-scale after initialisation.

scholarly journals Interannual Seesaw between the Somali and the Australian Cross-Equatorial Flows and its Connection to the East Asian Summer Monsoon

2014 ◽  
Vol 27 (11) ◽  
pp. 3966-3981 ◽  
Author(s):  
Chen Li ◽  
Shuanglin Li
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Yellow River ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Significant Negative Correlation ◽  
Subtropical High ◽  
Yellow River Valley ◽  
Asian Summer

Abstract The correlations among the summer, low-level, cross-equatorial flows (CEFs) over the Indian–west Pacific Ocean region on the interannual time scale are investigated by using both the NCEP–NCAR reanalysis and 40-yr ECMWF Re-Analysis (ERA-40) datasets. A significant negative correlation (seesaw) has been illustrated between the Somali CEF and the three CEFs north of Australia (the South China Sea, Celebes Sea, and New Guinea; they are referred to in combination as the Australian CEF). A seesaw index is thus defined with a higher (lower) value representing an intensified (weakened) Somali CEF but a weakened (intensified) Australian CEF. The connection of the seesaw with the East Asian summer monsoon (EASM) is then investigated. The results suggest that an enhanced seesaw corresponds to an intensified EASM with more rainfall in north China, the Yellow River valley, and the upper reach of the Yangtze River. The seesaw reflects the opposite covariability between the two atmospheric action centers in the Southern Hemisphere, Mascarene subtropical high, and Australian subtropical high. Whether the seesaw–EASM connection is influenced by El Niño–Southern Oscillation (ENSO) or the Indian Ocean SST dipole mode (IOD) is analyzed. The results remain unchanged when the ENSO- or IOD-related signals are excluded, although ENSO exerts a significant influence. This implies an additional predictability for the EASM from the CEF seesaw.

scholarly journals Improving the Prediction of the East Asian Summer Monsoon: New Approaches

2012 ◽  
Vol 27 (4) ◽  
pp. 1017-1030 ◽  
Author(s):  
Ke Fan ◽  
Ying Liu ◽  
HuoPo Chen
Keyword(s):  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Statistical Prediction ◽  
Multimodel Ensemble ◽  
Prediction Ability ◽  
Asian Summer ◽  
Prediction Approach

Abstract East Asian summer monsoon (EASM) prediction is difficult because of the summer monsoon’s weak and unstable linkage with El Niño–Southern Oscillation (ENSO) interdecadal variability and its complicated association with high-latitude processes. Two statistical prediction schemes were developed to include the interannual increment approach to improve the seasonal prediction of the EASM’s strength. The schemes were applied to three models [i.e., the Centre National de Recherches Météorologiques (CNRM), the Met Office (UKMO), and the European Centre for Medium-Range Weather Forecasts (ECMWF)] and the Multimodel Ensemble (MME) from the Development of a European Multimodel Ensemble System for Seasonal-to-Interannual Prediction (DEMETER) results for 1961–2001. The inability of the three dynamical models to reproduce the weakened East Asian monsoon at the end of the 1970s leads to low prediction ability for the interannual variability of the EASM. Therefore, the interannual increment prediction approach was applied to overcome this issue. Scheme I contained the EASM in the form of year-to-year increments as a predictor that is derived from the direct outputs of the models. Scheme II contained two predictors: both the EASM and also the western North Pacific circulation in the form of year-to-year increments. Both the cross-validation test and the independent hindcast experiments showed that the two prediction schemes have a much better prediction ability for the EASM than does the original scheme. This study provides an efficient approach for predicting the EASM.

A New Upper-Level Circulation Index for the East Asian Summer Monsoon Variability

2015 ◽  
Vol 28 (24) ◽  
pp. 9977-9996 ◽  
Author(s):  
Guijie Zhao ◽  
Gang Huang ◽  
Renguang Wu ◽  
Weichen Tao ◽  
Hainan Gong ◽  
...  
Keyword(s):  
East Asia ◽  
Summer Monsoon ◽  
East Asian Summer Monsoon ◽  
Southern Oscillation ◽  
Asian Summer Monsoon ◽  
East Asian ◽  
Late Summer ◽  
Good Choice ◽  
Circulation Index ◽  
Asian Summer

Abstract The East Asian summer monsoon (EASM) and its variability involve circulation systems in both the tropics and midlatitudes as well as in both the lower and upper troposphere. Considering this fact, a new EASM index (NEWI) is proposed based on 200-hPa zonal wind, which takes into account wind anomalies in the southern (about 5°N), middle (about 20°N), and northern areas (about 35°N) of East Asia. The NEWI can capture the interannual EASM-related climate anomalies and the interdecadal variability well. Compared to previous indices, the NEWI shows a better performance in describing precipitation and air temperature variations over East Asia. It can also show distinct climate anomalous features in early and late summer. The NEWI is tightly associated with the East Asian–Pacific or the Pacific–Japan teleconnection, suggesting a possible role of internal dynamics in the EASM variability. Meanwhile, the NEWI is significantly linked to El Niño–Southern Oscillation and tropical Indian Ocean sea surface temperature anomalies. Furthermore, the NEWI is highly predictable in the ENSEMBLES models, indicating its advantage for operational prediction of the EASM. The physical mechanism of the EASM variability as represented by the NEWI is also explicit. Both warm advection anomalies of temperature by anomalous westerly winds and the advection of anomalous positive relative vorticity by northerly basic winds cause anomalous ascending motion over the mei-yu–changma–baiu rainfall area, and vice versa over the South China Sea area. Hence, this NEWI would be a good choice to study, monitor, and predict the EASM.

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